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Table of Content

    12 August 2007, Volume 33 Issue 08
    • ORIGINAL PAPERS
      Estimating Grain Protein Content with Canopy Spectral Reflectance in Rice
      ZHOU Dong-Qin;ZHU Yan;YAO Xia;TIAN Yong-Chao;CAO Wei-Xing
      Acta Agron Sin. 2007, 33(08):  1219-1225. 
      Abstract ( 1852 )   PDF (2198KB) ( 1040 )   Save
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      Grain protein content is a key index for evaluating rice quality. We investigated the quantitative relationships between grain protein content and canopy reflectance spectra at different growth stages in rice (Oryza sativa L.) on the basis of the data from the field experiments involving different cultivars and nitrogen levels in four years. Experiment 1 and 2 were both conducted with one cultivar, Wuxiangjing 9, and five N application levels of 0, 75, 150, 225, and 300 kg ha-1 in 2002 and 2003. Experiment 3 included three cultivars (Wuxiangjing 9, Huajing 2, Nipponbare) with four N application levels of 0, 105, 210, and 315 kg ha-1 in 2004. Experiment 4 was designed with two cultivars (Wuxiangjing 14, 27123), and four N application levels of 0, 90, 270, and 420 kg ha-1 in 2005. Canopy spectral reflectance (460–1 650 nm) date at jointing, booting, heading, filling, and ripening stages of rice in the different field experiments were measured with MSR-16 multi-spectral radiometer, and corresponding leaf area index and grain protein content were also determined. Then the relationships of grain protein content to canopy reflectance of single band and all two-band combinations were analyzed.
      The results showed that there were significant negative correlation between grain protein content and canopy spectral reflectance at 460–710 nm and positive correlation at 760–1 220 nm after jointing, with best performance from the relationship at 760 nm and booting stage. The relationships of grain protein content to the ratio, differential and normalized difference vegetation indices of all bands and red edge parameters were also analyzed, then fifteen parameters were selected. Through step regression analysis on 16 better spectral parameters, the differential vegetation index of R1500 and R950 was found to be the best parameter for predicting grain protein content (GPC) in rice. The derived equation, GPC =0.15 × DVI (1 500, 950) + 3, was tested with the observed data from the other independent experiments. The estimation precision was 0.56–0.86, estimation accuracy was 0.85–1.18, and RMSE was 3.51%–19.9%, indicating a good fit between the predicted and observed values of grain protein content. It is concluded that the present spectral index model is feasible and useful for estimating grain protein content in rice with different cultivars and nitrogen levels.

      Cloning, Expression and Characterization of an ADP-ribosylation Factor Gene from Cotton (Gossypium hirsutum L.)
      HOU Lei;LI Jia-Bao;LUO Xiao-Ying;WANG Wen-Feng;XIAO Yue-Hua;LUO Ming;PEI Yan
      Acta Agron Sin. 2007, 33(08):  1226-1231. 
      Abstract ( 1996 )   PDF (2232KB) ( 965 )   Save
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      Cotton (Gossypium hirsutum L.) is the most important fiber crop in the plant kingdom. In addition to their economic importance, cotton fibers are an ideal experimental material to study cell differentiation, cell elongation, cell wall biosynthesis. ADP-ribosylation factors (ARFs), a subfamily of the small GTP binding proteins superfamily, are believed to participate in vesicular transport and signal transduction events in the cell. The elongation of cotton fiber requires vesicle trafficking to deposit new wall material and increase plasma membrane area, but the function of ARF within the key developmental processes of fiber is still unknown. The positive clone was screened from cotton anther cDNA library using GHA27 as a probe, and its corresponding genome sequence was obtained by PCR. Southern and Northern blotting were employed to determine the gene copy number and gene expression level of GhARF1 in cotton. The cDNA, designated as GhARF1, encoded a polypeptide of 181 amino acid residues with significant homology to the ADP-ribosylation factor (ARF) of mammalian, plant, yeast. Its deduced amino acid sequence showed that the 20.7kDa protein had consensus with GTP-binding domain P(GLDAAGKT), G’(DVGGQ), G(NKQD). The DNA sequence of GhARF1 is 1.5kb in size, including five exons and four introns. Northern blotting showed that GhARF1 transcript was detected mainly in root and corolla rather than in shoot, bud, leaf, cotyledon and ovule, and maximally in fiber. Southern hybridization suggested that GhARF1 is encoded by multi-copies in the genome of Gossypium herbaceum or Gossypium hirsutum. High transcript level of GhARF1 in fiber cells suggests that GhARF1 may play a role in cotton fiber development, especially in fiber cell elongation.

      Molecular Marker Analysis on Common Wheat Landrace Chinese Spring Alien Chromosome Lines Derived from Thinopyrum bessarabicum Löve
      CHEN Hua-Feng;QIAN Bao-Li;ZHUANG Li-Fang;CHEN Quan-Zhan;FENG Yi-Gao;PEI Zi-You;QI Zeng-Jun;CHEN Pei-Du;LIU Da-Jun
      Acta Agron Sin. 2007, 33(08):  1232-1239. 
      Abstract ( 1889 )   PDF (4506KB) ( 1099 )   Save
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      Thinopyrum bessarabicum Löve and Chinese Spring-Thinopyrum bessarabicum amphiploid (the amphiploid hereafter) are reported with high salinity tolerance. Screen of molecular markers tagging different chromosomes of Thinopyrum bessarabicum would facilitate transfer of these genes or chromosomes into common wheat. Some specific proteins or enzymes, AFLP or RAPD markers have been described by different authors. However, use of SSR, STS, and RFLP markers identifying Thinopyrum bessarabicum chromosomes is seldom reported. To dig out the beneficial genes of this species, the amphiploid was introduced from Dr. Mujeeb-Kazi, CIMMYT, and several additions, and translocations have been independently developed and reported by Cytogentics Institute, Nanjing Agricultural University, China. Using SSR, STS, and RFLP markers of wheat and barley etc, 7 disomic additions, 3 alien lines including translocations and additions and 1 multiple additions were characterized in this study. The results revealed that 14 of 219 wheat SSRs, 8 of 126 barley STS and 2 wheat STS, 6 RFLP probes could be used to distinguish the chromosomes of Thinopyrum bessarabicum added in wheat. Of the alien chromosome lines, C7-17 and C7-17-2 were verified involving chromosome 1J encoding specific HMW-Glu subunit of Thinopyrum bessarabicum. Two STS markers MWG2303 (2HL) and NAU/Xibao15 (6S), one RFLP probe BCD135 (2BL) and 4 SSR markers (Cfd168 (2A), Xgwm526 (2B), Xgwm311 (2D), and Xgdm93 (4B)) could be used to tag the chromosomes added in CH05, while 6L probe PSR154 and one wheat 2AL-end STS KsuH9 failed to produce polymorphism indicating rearrangements occurred in this chromosome, therefore, the preliminary designed J3 based on the C-banded karyotype of Thinopyrum bessarabicum added in this line was deduced with closer relationship with group 2 chromosomes of wheat. Two STSs from 3HL(BCD269, MWG974), one probe PSR116 from wheat 3L and one SSR Xgwm114(3DS) could be used to tag the chromosomes added in CH09, the preliminary designed J7 was then deduced with closer relationship with group 3 chromosomes of wheat. One STS MWG808(7H), one probe mapped in the middle part of 4L(PSR163) and one SSR Xgdm131(3B) could be used to tag the chromosomes added in CH03,CH04 and CH34, while two other probes mapped in the distal part of 4L (WG114) and 4S(CDO669) without RFLPs, indicating these three additions might contain the same alien chromosomes, the preliminary designed J1, J2, and J? in these lines respectively were deduced with closer relationship with group 7 chromosomes of wheat, rearrangements with group 4 chromosomes also involved. Three SSR markers Xgdm35 (2D), Xgwm515 (2A, 2D), and Xgwm614 (2A, 2B, and 2D) could be used to tag the large segmental translocation chromosomes added in CH12, and small segmental translocation chromosomes contained in CH11 which also included another pair of alien chromosomes similar to that of CH05, this result indicated that these translocations with different segments might be derived from the same chromosome of Thinopyrum bessarabicum. 13 markers (5 barley STSs, 3 RFLP probes and 5 wheat SSRs) could be used to trace the chromosomes not involved in the present lines.

      Chain Length Distribution of Debranched Amylopectin and Its Relationship with Physicochemical Properties of Starch in Different Wheat Cultivars
      LI Chun-Yan;FENG Chao-Nian;WANG Ya-Lei;ZHANG Rong;GUO Wen-Shan;ZHU Xin-Kai;PENG Yong-Xin
      Acta Agron Sin. 2007, 33(08):  1240-1245. 
      Abstract ( 2380 )   PDF (2012KB) ( 1053 )   Save
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      Starch and its pasting and retrogradation properties appear to be one of the key factors determining the qualities of wheat products. Amylopectin structure in starch granules can be described by a cluster model. The chain-length distribution of amylopectin has been focused in researches because of its relation to physicochemical properties of starch. The long B chains render the starch granule strong and resilient, thus leading to the firm texture of cooked rice, while the shortage of such chains leads to weak granules resulting in soft cooked rice. Now more and more researchers show their attentions to the relationship between the structure and physicochemical properties of starch. We mainly studied chain length distribution of amylopectin debranched by isoamylase in waxy and non-waxy wheat (Triticum aestivum L.) at Yangzhou University, also analyzed the relationships between starch structure and starch physicochemical properties, which would provide some information for producing wheat with good grain quality and high yield. The blue value (BV) and maximum absorption (λmax) of amylose or amylopectin and the chain length distribution of debranched amylopectin were measured. The results showed that BV and λmaxAM of amylose were higher than those of amylopectin. The order of BV and λmax of amylopectin (λmaxAP) was medium-gluten wheat>weak-gluten wheat>strong-gluten wheat>waxy wheat. There was a positive correlation between BV and λmaxAP. Three kinds of components of debranched amylopectin molecular chain were got by Sephadex G75 from all different cultivars except waxy wheat cultivars. The weight percentage of long B-chain in debranched amylopectin was the lowest among three compositions, that of intermediate B-chain content was the second, that of short B-chain and A-chain contents accounting for about 65% were the highest. The order of long B-chain and intermediate B-chain percentage was weak-gluten wheat>strong-gluten wheat>medium-gluten wheat in normal types. Obvious differences among different cultivars in the same type were also observed. There was no long B-chain in amylopectin of waxy wheat. The proportion of long B-chain was highly significantly correlated with pasting parameters of RVA except breakdown (BD), and significantly correlated with crystalline degree. It might be assumed that physicochemical characteristics of starch in wheat grain were significantly affected by the long B-chain content.

      Genetic Map Construction and Apetalousness QTLs Identification in Rapeseed (Brassica napus L.)
      ZHANG Jie-Fu;QI Cun-Kou;LI Gen-Yi;PU Hui-Ming;CHEN Song;CHEN Xin-Jun;GAO Jian-Qin;CHEN Feng;GU Hui;FU Shou-Zhong
      Acta Agron Sin. 2007, 33(08):  1246-1254. 
      Abstract ( 1990 )   PDF (2213KB) ( 1047 )   Save
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      Apetalous rapeseed has the advantages of high solar radition utilization efficiency, low sclerotinia incidence ratio, strong root assimilation efficiency, and high yield potential owing to the loss of petal. Apetalousness is controlled by two to four recessive genes in rapeseed. All researchers consider the plants with less than 10% petalous degree (PD) as the apetalous, but the distribution of PD in segregation generation is consecutive. The apetalous should be treated as a quantitative trait to screen QTLs. In present research,an apetalous rapeseed line APL01 was crossed with a normal petalous line M083 to develop a segregating population BC1F1. This population was used to construct a genetic map and identify QTLs affecting the apetalous in rapeseed (Brassica napus L.). Totally, 219 SRAP, 25 SSR, and 7 RAPD markers were used to construct a genetic map containing 19 linkage groups in rapeseed. This map was aligned with the ultradense genetic recombination map for B. napus L., and four QTLs were identified by WinQtlCart. QAP5 was located in the region of A0226Bb152–m31e40b on linkage group (LG) N5, which could explain 3.71% of the petalous variation in segregation population BC1F1. QAP6 was mapped in the region of m25e7–OPY9 on LG N6, and accounted for 3.02% of phenotypic variation. QAP8 was located between A0226Gb468–m29e20 on LG N8 and explained 30.94% of phenotypic variation. QAP15 was located in the region of m21e4b–A0225Bb201 on LG N15, and accounted for 21.96% of phenotypic variation. Two main-effect QTLs of them (QAP8 and QAP15) could be applied in marker-assisted selection for apetalous rapeseed breeding, and the other two QTLs (QAP5 and QAP6) were modified genes.

      Physiological Response of Xiaobingmai (Triticum aestivum -Agropyron intermedium) to Salt-Stress and Alkali-Stress
      YANGChun-Wu;LI Chang-You;YIN Hong-Juan;JU Miao;SHI De-Cheng
      Acta Agron Sin. 2007, 33(08):  1255-1261. 
      Abstract ( 1877 )   PDF (2159KB) ( 1011 )   Save
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      Land salinization-alkalization is a widespread environmental problem. The problem can be further classified, in terms of the salt characteristics, into salt-stress and alkali-stress. In fact, the destructive effects caused by alkali-stress is more serious than that by salt-stress. However, the information about alkali-stress is little up to the present. The resistance to salt and alkali stresses is stronger in Xiaobingmai (Triticum aestivum -Agropyron intermedium) than in other varieties of wheat. The cultivar Xiaobingmai 33 has been planted over some salt-alkalized areas, but its resistance to salt and alkali stresses is few studied yet. Therefore, Xiaobingmai 33 was chosen as the experimental materials to explore its physiological response to salt and alkali stresses and the difference between salt-stress and alkali-stress.The seedlings of Xiaobingmai 33 were treated for 12 days under five conditions of salt-stress and six conditions of alkali-stress, which were established by mixing NaCl and Na2SO4 or NaHCO3 and Na2CO3 at 1:1 molar ratio respectively. The concentration range of treatments was from 60 to 300 mmol L-1 for the salt-stress, and 30 to 180 mmol L-1 for the alkali-stress. Six strain indices including relative growth rate (RGR), water content, malondialdehyde (MDA) content, electrolyte leakage rate, chlorophyll content, and carotenoid content, and the contents of five solute including Na+, K+, proline, betain and organic acid, were determined. The physiological responses of Xiaobingmai 33 to salt-stress and alkali-stress were analyzed and compared in order to further identify the difference of both stresses.
      The results showed that the decrease extents of RGR and water content and the increase extents of MDA and electrolyte leakage rate under-alkali stress were greater than those under salt-stress with increasing stress intensity. The contents of chlorophyll and carotenoid didn’t change under salt stress, but decreased sharply under alkali-stress. Under both stresses, the contents of Na+ , proline, and betain increased, while K+ content decreased, and the changing degree under salt-stress was higher than that under alkali stress. In addition, organic acid content increased significantly under alkali-stress, but decreased slightly under salt-stress. In conclusion, all the strain responses to alkali-stress were more marked than those to salt-stress. The maximum concentration for Xiaobingmai 33 in resistance to salt-stress was 300 mmol L-1, and that to alkali-stress was only 150 mmol L-1 under the present experimental conditions. Alkali-stress caused great decrease of photosynthetic pigment content, which might be one of the reasons that the effect of alkali-stress was more severe than that of salt-stress. The accumulation of organic acids might be a special physiological mechanism of Xiaobingmai response to alkali-stress. The present study indicate that salt-stress and alkali-stress are two different stresses, not only in their effects on plant, but also in the response of plant to them.

      Genetic Analysis and SSR Mapping of Stem Rust Resistance Gene from Wheat Mutant D51
      YIN Jing;WANG Guang-Jin;ZHANG Hong-Ji;SUN Yan;DIAO Yan-Ling;HUANG Jing-Hua;GUO Qiang;XIAO Jia-Lei;Ma Feng-Ming;SUN Guang-Zu
      Acta Agron Sin. 2007, 33(08):  1262-1266. 
      Abstract ( 1980 )   PDF (1766KB) ( 913 )   Save
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      Stem rust caused by Puccinia graminis f. sp. tritici is one of the main diseases of wheat (Triticum aestivum L.) worldwide. Wheat mutant line D51, form a highly susceptive cultivar ‘L6239’ to the three races notated and cultured with immature embryo, shows resistance to prevailing races 21C3CPH, 21C3CKH, and 21C3CTR of P. graminis f. sp. tritici in China. In this paper, number of the resistance genes in mutant D51 and the expression stages were studied with inoculation identification and microsatellite (SSR) marker analysis. Two F1 populations from the crosses of D51×L6239 (60 individuals) and D51×Chinese Spring (60 individuals), their F2 populations (185 and 175 individuals respectively) at seedling and one F2 populations derived from the cross of D51×L6239 (194 individuals) at adult stage were inoculated with pathogen race 21C3CPH to test their resistance. All F1 individuals of the two crosses were immune to stem rust at both seedling and adult stages. The response pattern of the three F2 populations showed that the R:S segregation ratio fit 3:1, suggesting the stem rust resistance of D51 controlled by a single dominant gene, and expressed in whole growth period. The identification to stem rust resistance by F3 progeny test confirmed the credibility of F2 population test. Segregating populations and small population analyses were used to identify chromosomal region and molecular markers linked to the gene by SSR markers method. A total of 675 SSR markers and 185 individuals of D51×L6239 F2 population were used to search genetically linked makers to the target gene. Using Mapmaker3.0 and Map-draw with Kosambi’s function and other options left at default values, molecular mapping revealed that the gene was located on the chromosome 5DS, and linked with and blanked by two SSR markers Xgwm190 and Xwmc150 at 18.58 and 21.33cM, respectively. According to references reported, the only one stem rust resistant gene Sr30 is located on the wheat chromosome 5DL, and has no resistance to 34C2MKK and 34C2MFK, and parent L6239 of mutant D51 is without resistance to 21C3CPH, 21C3CTK and 21C3CTR, but with resistance to 34C2MKK and 34C2MFK.The results above indicate that the gene identified in this paper might be a novel resistance gene to stem rust, designated SrD51 tentatively.

      Diurnal Changes of Photosynthetic and Physiological Parameters in Different Male Sterile Lines of Wheat
      JIAO Jian;ZHANG Ai-Min;HAO Yuan-Yuan;WANG Da-Wei;WANG Lin;QIU Xin-Min
      Acta Agron Sin. 2007, 33(08):  1267-1271. 
      Abstract ( 1754 )   PDF (1617KB) ( 1033 )   Save
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      In order to study the cytoplasmic effects of male sterile wheat, male sterile lines of CHA (chemical hybridizing agent) and cytoplasmic K (Aegilops kotschyi), T (Triticum timopheevi), V (Aegilops ventricosa) types of male sterile wheat at different developmental stages were compared with their maintainer lines in the diurnal changes of photosynthetic and physiological parameters, comprising net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), water use efficiency (WUE), photon flux density (PFD), intercellular CO2 concentration (Ci), atmospheric CO2 concentration (Ca), leaf temperature (Ti), atmospheric temperature (Ta), and stomatal limiting value (Ls). And these parameters may reflect the photosynthetic efficiency of the leaves and environmental adapting capability of the plant. The experiment was conducted to analyze the diurnal changes and the physiological mechanism of photosynthetic midday-depression, the response to male sterile cytoplasms of female parent genotypes and the differences of photosynthetic and physiological parameters of 4 male sterile lines and their maintainer lines, which can reflect differences of heredity of 4 male sterile cytoplasms under the same nuclear background and also exhibit differences of the effect of nuclear-cytoplasmic interaction. The result indicated that, the curve of diurnal changes of Pn presented two peak values, with one peak at 10:00 higher than the other at 14:00. And the phenomenon of photosynthetic midday-depression of leaf happened at noon. The diurnal changes of Pn was positively correlated with Gs, Ci and negatively correlated with Ls, and the correlation coefficients were 0.8187*, 0.8136*, and -0.8496* respectively. Accompanied by the decline of Gs, Ci and the raise of Ls, Pn declined distinctly in midday, which means the limitation of Pn by stomatal factor. Compared with their maintainer lines, CHA and K, T, V-male sterile lines had lower Pn values, decreasingly 0.88, 2.76, 3.30, and 2.04 μmol CO2 m-2 s-1 respectively, indicating that the CHA and K, T, V-cytoplasm has negative effects on Pn with different extent, especially T and K-types. K, T, V cytoplasmic male sterile lines had lower WUE values than their maintainer lines, decreasingly 0.94–1.54 μmol CO2 mmol-1 H2O, and indicating that K, T, V-cytoplasm has significantly negative effects on WUE. Compared with the maintainer lines, CHA-sterile lines has no significant difference in WUE values, indicating chemical hybriding agent (BAU-9403) has no significantly negative effects on the water use efficiency of wheat flag leaf. The influences of damage caused by BAU-9403 were less than the negative effects of other male sterile cytoplasms. Moreover, the Pn value varied between genotypes of different female parents, Pn of Ji 5418 and its CMS lines showed significant or highly significant differences with that of Tai 911289, indicating that genotypes of female parents have different effects on different cytoplasms in Pn. This result also demonstrates the enormous potential for improving the photosynthetic capability in Ji 5418. Therefore, it is better to reduce the negative effects of male sterile cytoplasms on photosynthetic function of wheat by selecting preponderant recurrent parent to make backcross in a breeding project.

      Photosynthetic Characteristics and the Regulation of PhotosystemⅡ Function in Salt-stressed Sweet Sorghum Seedlings
      GE Jiang-Li;SHI Lei;GU Wei-Bin;TANG Yu-Dan;ZHANG Jin-Zheng;JIANG Chaung-Dao;REN Da-Ming
      Acta Agron Sin. 2007, 33(08):  1272-1278. 
      Abstract ( 2174 )   PDF (1996KB) ( 1083 )   Save
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      Gas exchange and chlorophyll fluorescence quenching kinetics were investigated to explore the effect of salt stress on carbon assimilation and photosystem Ⅱ photochemical efficiency in sweet sorghum seedlings in this study. Chlorophyll content, relative water content and membrane lipid peroxidation were not significantly changed in sweet sorghum seedlings when salt (NaCl) concentration was below 100 mmol L-1; while, 200 mmol L-1 NaCl treatment induced an obvious decrease in chlorophyll content, relative water content and an increase in membrane lipid peroxidation. Net photosynthetic rate (Pn) and stomatal conductance (Gs) began to decline strongly at NaCl concentration higher than 50 mmol L-1, whereas, the intercellular CO2 concentration (Ci) increased strikingly. During this process, the stomatal limiting value (Ls) decreased with the increase of salt treatment. More important, the depression of carbon assimilation under salt stress could not be restored by the enhancement of CO2 concentration. The measurement of chlorophyll fluorescence showed that the initial fluorescence yield (Fo), the maximum fluorescence yield (Fm) and the maximal quantum yield of photosystem Ⅱ photochemistry (Fv/Fm) significantly went down in 200 mmol L-1 NaCl treated seedlings. Moreover, chlorophyll fluorescence quenching kinetics parameters were not affected by 50 mmol L-1 NaCl treatment. When NaCl concentration was above 50 mmol L-1, the efficiency of open centers of photosystem Ⅱ (Fv’/Fm’),photochemical quenching (qp) and actual photosystem Ⅱ efficiency (ΦPSⅡ) decreased sharply, while non-photochemical quenching (NPQ) increased gradually. Therefore, we suggest that the decreased net photosynthetic rate (Pn) in salt-stressed sweet sorghum seedlings is mainly due to non-stomatal limitation; the depression of carbon assimilation capacity significantly alters the excited energy distribution. Under moderate salt stress (100 mmol L-1 NaCl), it is the enhancement of thermal dissipation that dissipate excess excited energy protecting sweet sorghum seedlings against photodamage; however, severely salt treatment (200 mmol L-1 NaCl) causes the reduction of light absorption and improvement of thermal dissipation for keeping the balance in light capture and utilization.

      Somatic Embryogenesis and Plant Regeneration in Wild Cotton Species of G Genome
      WANG Jing-Er;SUN Yu-Qiang;ZHANG Fang-Biao;SHEN Xiao-Jia;ZHU Shui-Jin
      Acta Agron Sin. 2007, 33(08):  1279-1285. 
      Abstract ( 1804 )   PDF (12475KB) ( 1669 )   Save
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      The wild cotton species of G genome in Australia have some outstanding characters such as the delayed gland morphogenesis trait that is available in the utilization of cotton seeds and provides higher resistance to pest and diseases. However, the upland cotton germplasm with the trait has not been obtained due to the distant relationship between the G genome species and upland cotton. Protoplast fusion technique which depends on the success in the somatic culture of two different species can avoid sexual incompatibility in convention hybridization. Fewer papers have been reported on plant regeneration from somatic culture successfully in wild cotton species. In this paper, callus inducing and plant regeneration of the two wild cotton species G genome, Gossypium australe F. Muell. and Gossypium nelsonii Fryx. were studied through the regulation of culture conditions such as plant growth regulators (PGR) and carbon sources with the Gossypium klotzschianum Anderss of D genome as a control. The results indicated that under the same condition, the frequency of somatic embryo germination and the plant regeneration ability of G. klotzschianum were high, and most of the regenerated plants from G. klotzschianum were normal. For G. nelsonii, although many plantlets were regenerated, most of them were monstrous , while that of G. australe was still staying at the stage of somatic embryo, indicating that the plant regeneration of G genome cotton species obtained in our experiment was more difficult than that of D genome species. Furthermore, the callus of G genome species induced in the medium with the hormone combination of 0.1 mg L-1 KT + 0.1 mg L-1 2,4-D held good for cell differentiation, and it was better for proliferation of the embryogenic callus in the medium with 0.2 mg L-1 KT + 0.5 mg L-1 IBA. It was helpful for initiation of somatic embryos when IBA concentration in the medium was decreased to 0.25 mg L-1 and KT was increased up to 0.3 mg L-1, and the medium of MSB5 with 0.15 mg L-1 KT and 0.5 mg L-1 NAA was in favor to plant regeneration. In addition, glucose, the sugar source in tissue and cell culture, was good for callus induction from the G genome cotton species, while maltose was even better than glucose for proliferation of embryogenic callus and germination of somatic embryo. This report provides an useful technique for somatic culture of the wild cotton species, and also ensures the protoplast fusion feasibly between these wild cotton species and other cotton species to converge several good traits into a new germpalsm. However, it is needed to study further about the various culture factors and conditions for building a quick and high efficient tissue culture regeneration technique of the two wild cotton species of G genome.

      Relationship between Chlorophyll Fluorescence Parameters and Spectral Reflectance Characteristics in Wheat Leaves
      ZHU Yan;TIAN Yong-Chao;MA Ji-Feng;YAO Xia;LIU Xiao-Jun;CAO Wei-Xing
      Acta Agron Sin. 2007, 33(08):  1286-1292. 
      Abstract ( 1840 )   PDF (8538KB) ( 1213 )   Save
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      It is of significant importance for using leaf spectral reflectance characteristics to estimate leaf chlorophyll fluorescence parameters in crop plants. We carried out two filed experiments in Nanjing to investigate the relationships between chlorophyll fluorescence parameters and spectral reflectance characteristics in top four leaves under different nitrogen levels in wheat (Triticum aestivum L.) cultivars Ningmai 9 (low protein content), Huaimai 20 (medium protein content), and Yumai 34 (high protein content). Experiment one was conducted with Ningmai 9 and Huaimai 20 and five nitrogen application levels of 0, 75, 150, 225, and 300 kg ha-1 in 2003 to 2004. Experiment two was designed for Ningmai 9 and Yumai 34 with three nitrogen application levels of 0, 90, and 270 kg ha-1 in 2004 to 2005. The dynamic change patterns and interrelationships between chlorophyll fluorescence parameters and spectral reflectance in top four leaves of wheat cultivars under different nitrogen levels in two years were analyzed. The results indicated that the leaf chlorophyll fluorescence parameters Fv/Fm and Fv/Fo in wheat increased with increasing nitrogen rates, whereas the leaf spectral reflectance varied distinctly with nitrogen rates, leaf positions and growth process. The correlations between chlorophyll fluorescence parameters and spectral reflectance in the top 1st and 2nd leaves were stabilized in the ranges of visible light (520–680nm) and near infrared light (750–850nm). The leaf reflectance spectral indices DVI (750, 550), DVI (735, 690) and TVI (750, 670, 550) were all highly correlated with the leaf chlorophyll fluorescence parameters Fo, Fm, Fv, Fv/Fm, Fv/Fo, Fs, Fm’, Fo’, Fv’, and Fv’/Fm’ in top 2 leaves, and the DVI (750, 550) had the best correlation. In addition, there were no obvious differences on regression coefficients among different cultivars and growth stages. These results suggested that it is feasible to monitor leaf chlorophyll fluorescence parameters by leaf reflectance spectra in wheat.

      Dynamic Changes of Callose in Microsporogenesis and Microgametogenesis of Rice (Oryza sativa L.)
      ZHANG Zhi-Sheng;LU Yong-Gen;LIU Xiang-Dong;FENG Jiu-Huan
      Acta Agron Sin. 2007, 33(08):  1293-1298. 
      Abstract ( 2524 )   PDF (1898KB) ( 1014 )   Save
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      Callose plays an important role in microsporogenesis and pollen development. However, few studies with the emphasis on callose changes have been carried out in rice. Taichung 65 was employed to investigate the dynamic changes of callose in microsporogenesis and microgametogenesis of rice by using techniques of intact fresh anther epifluorescence microscopy, PEG section epifluorescence microscopy, semi-thin section light microscopy, and TEM. It was found that callose appears in microsporangium at the microspore mother cell formation stage. During meiosis, callose deposition in microspore mother cell firstly occurs on the primary cell wall in the central region of the anther locule, and the intact callose wall appears at the meiotic diakenesis I. In microgametogenesis, callose deposits in tapetal cells and begins to accumulate around microspore nucleus at the early microspore stage, callose deposition around microspore nucleus continues through uninucleate microspore stage. At the late microspore stage, the degeneration of the tapetal cell begins, and the thickening of the endothecium cell wall by callose happens. At the early bicellular pollen stage, accumulation of callose in the cytoplasm of the vegetative cell occurs , and the callose wall of the generative cell is formed and then degraded before the third nuclear migration. At the mature pollen stage, certain amount of callose accumulates in cytoplasm of the vegetative cell. These results indicate that callose metabolism is active and very important not only in microsporogenesis but also in microgametogenesis in rice.

      Genetic Dissection for Grain Yield and Its Components Using an “Immortalized F2 Population”in Maize
      TNAG Ji-Hua;YAN Jian-Bing;MA Xi-Qing;TENG Wen-Tao;MENG Yi-Jiang;DAI Jing-Rui;Li Jian-Sheng
      Acta Agron Sin. 2007, 33(08):  1299-1303. 
      Abstract ( 2162 )   PDF (2565KB) ( 1120 )   Save
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      Genetic dissection for grain yield and its components can provide a new strategy for crop breeding, and it play an important role in improving agricultural production. For dissecting the genetic basis of grain yield and its components, a set of recombinant inbred line (RIL) derived from an elite maize hybrid Yuyu 22, which is planted broadly in China, was used to constructed an “immortalized F2”(IF2) maize (Zea mays L.) populations including 441 single crosses. The frequency of molecular marker loci for the IF2 population was analyzed using 253 different SSR markers, the results demonstrated that the genetic components and gene frequency of the IF2 population was similar to its F2 population in molecular maker level, theoretically it could replace F2 population in related genetic analyses. The IF2 population was evaluated in one environment over two years, and the genetic mechanism of grain yield and its components was dissected through QTL analysis using composite interval mapping (CIM) method. These results showed that grain yield had positive significant correlation with its three components at P<0.01 or P<0.05 level, and in the three components, ear length had negative significant correlation with row number and 100-grian weight at P<0.05 level. A total of 8 QTL were detected for grain yield, 8 for ear length, 11 for row number and 5 for 100-grain weight.

      Effect of Continuous Cropping on Photosynthesis and Metabolism of Reactive Oxygen in Peanut
      WANG Cai-Bin;WU Zheng-Feng;CHENG Bo;ZHENG Ya-Ping;WAN Shu-Bo;GUO Feng;Chen Dian-Xu
      Acta Agron Sin. 2007, 33(08):  1304-1309. 
      Abstract ( 1881 )   PDF (470KB) ( 1182 )   Save
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      Continuous cropping is one of the main factors that affect the peanut yield. There are about 250 000 ha continuous cropping areas with a yield loss of about 110 000 t every year in Shandong province. Understanding the effect of continuous cropping on peanut photosynthesis and metabolism is very important to explore the yield-reducing reasons and relieve the loss of continuous cropping. In this study, photosynthetic performance of three peanut cultivars (8130, from Virginia; Luhua 12, from Spanish; Luhua 14, from interspecies crossing) was compared in field experiments with two farming patterns of continuous cropping(CP)and rotation cropping (RP) and the reactive oxygen metabolizing feature of plant under different cropping modes (One-year continuous cropping, T1; two-year cropping, T2; rotation cropping, T0) was observed using pool test to understand the mechanism of CP press on growth and development of peanut. Results showed that CP press of peanut significantly decreased the rate of leaf net photosynthesis(Pn)and canopy apparent photosynthesis (CAP) , as well as leaf area index(LAI), while little influenced chlorophyll (Chl) content. Significant positive correlations of LAI with CAP and with crop growth rate (CGR), as well as Chl content with Pn were observed. Therefore, the decrease of LAI was the dominant factor that hampered dry mass accumulation and lowered pod production in CP peanut. Sensitivity of different peanut variety types to CP press was evident: Luhua 12 >Luhua14>8130. The change of all the characters mentioned above became larger with the plant development. CP decreased the activities of SOD, POD, and CAT, and increased MDA content in leaf, and the changes were larger when the year of CP increased. CGR was significantly correlated with activities of POD and SOD in leaves and not correlated with MDA, CAT and soluble protein. The activity decrease of protective enzyme, such as POD and SOD, was one of the reasons for poor growth and development and early senescence in CP peanut.

      Cloning and Characterization of One β-1,3-glucanase Gene cDNA in Cotton (Gossypium barbadense L.)
      GAO Yu-Long;GUO Wang-Zhen;WANG Lei;ZHANG Tian-Zhen
      Acta Agron Sin. 2007, 33(08):  1310-1315. 
      Abstract ( 1899 )   PDF (2085KB) ( 858 )   Save
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      β-1,3-glucanase genes are involved in diverse physiological and developmental processes, including microsporogenesis, pollen germination, fertilization, seed germination, and defense against pathogens. β-1,3-glucanase genes related to plant resistance are the members of a large family of proteins collectively referred to as the pathogenesis- related (PR) proteins. Several β-1,3-glucanase genes have been cloned from cotton, but the majority of them are involved in fiber development and are independent of resistance. Based on the nucleotide sequence which was isolated previously by our laboratory, we cloned one full length cDNA of β-1,3-glucanase gene (GbGLU) from Hai7124 by RACE method. DNA sequence analyses showed that the size of cDNA cloned was 1 266 bp, and it included an open reading frame of 1 086 bp that encoded a polypeptide of 361 amino acids residues with the calculated Mw of 39.66 kD and the predicted pI of 9.15. The deduced amino acid sequence of GbGLU contains conserved domain of Glycosyl hydrolases family 17 and has the N-terminal signal peptide composed of 26 animo acids residues. Southern-blot analysis indicated that there is single copy of GbGLU within cotton genome. The expression analysis of GbGLU gene in cotton root infected by Verticillum dahliae strain VD8 showed that its expression was detectable at 48h and 96h after inoculation. Glucanase genes cloned from cotton could be divided into three classes according to phylogenetic analysis and possess conserved motif of Glycosyl hydrolases family 3, 9, and 17, respectively. In addition, we find that glucanase related with resistance response from cotton and other plants possesses the motif of Glycosyl hydrolases family 17. And therefore, we suggest that conserved motif of Glycosyl hydrolases family 17 might be the function motif contributing to resistance response.

      Matter Production and Resources Use Efficiency of Double-Cropping Silage Maize System
      WANG Mei-Yun;REN Tian-Zhi;ZHAO Ming;LI Shao-Kun;WANG Xiao-Bo;LI Li-Juan;CHEN Chang-Li
      Acta Agron Sin. 2007, 33(08):  1316-1323. 
      Abstract ( 1846 )   PDF (309KB) ( 1485 )   Save
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      The conventional cropping systems were winter wheat-summer maize and single spring maize in the two harvest regions in the middle of China. However, with the increasing of market requirement for animal products, the cropping systems have been changed and forage production enhanced recently. In order to explore the new cropping system which was benefit for the livestock development using silage as food of saving grain,high matter production and resources use efficiency, the field experiments were conducted in the two harvest temperature limited regions of Beijing in 2004 and 2005. The ecologic elements of radiation, temperature and rainfall were detected by U.S.A BR-CR23 Automatic Energy Balance System and dry matter production was detected. Also matter production and resources use efficiency were compared between double-cropping silage maize (Zea mays L.) systems and conventional cropping systems, which were winter wheat -summer maize and single spring maize systems. The results showed that anniversary production efficiency of dry matter, energy production, radiation production efficiency, light energy production efficiency, temperature production efficiency and water production efficiency were 10.3%, 11.9%, 12.5%, 60.7%, 22.5%, and 36.3% more in double-cropping mulching film silage maize-maize system than in conventional winter wheat-summer maize system, respectively, so was it compared with spring maize. These results indicate that double cropping silage maize system performs higher yield and high production efficiency in natural resources use because of high photosynthetic traits of double-C4 plant, and longer growth and development period by the optimization technological measures of the double-cropping-incorporate cultivation: mulching cultivation in the first reason, varieties configuration in two reasons and the growing time distribution in whole year, and so on. Therefore, the cropping system can raise natural resources use efficiency and fully exert the common effect of light, temperature and water in a whole growth and development period. The novel system opens a new way for the cropping diversity and effective production in this region. The management is simple and the cost is low for silage maize planting, so it has better economic benefit and a broad applied prospect.

      Effects of Endogenous Hormones on Pre-harvest Sprouting in Siliqua of Rapeseed (Brassica napus L.)
      CHEN Guang-Yao;WANG Guo-Huai;LUO Feng;NIE Ming-Jian
      Acta Agron Sin. 2007, 33(08):  1324-1328. 
      Abstract ( 2202 )   PDF (1632KB) ( 910 )   Save
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      Rapeseed is one of the most important oil crops in China. It often encounter with the high temperature and humidity or continuous raining at the maturity stage, which results in pre-harvest sprouting. Pre-harvest sprouting will cause the decrease of seed yield and quality. In order to screen out Brassica napus lines resistant to pre-harvest sprouting and elucidate the major factor(s) inhibiting pre-harvest sprouting,the rate of pre-harvest sprouting and germination of the freshly harvested seeds of the five Brassica napus lines including 832, 780, 1-1, 1-13, 8-6 were investigated under field conditions or under various stimulated conditions in laboratory, and the contents of the endogenous hormones abscisic acid (ABA), indole acetic acid (IAA), cytokinin (CK) in fresh seeds and shells were determined with high performance liquid chromatography (HPLC). The results showed that there were significantly different rates of pre-harvest sprouting among different lines under field condition and under various stimulated conditions in laboratory, but no significant difference in seed germination rate after five days of the germination text. The higher ABA content in shells the lower rate of pre-harvest sprouting. The ABA content in shells was significantly and negatively correlated with rate of pre-harvest sprouting (r=-0.8941). CK in shells could obviously increase the rate of pre-harvest sprouting while IAA in seeds could promote early seed germination. Treatments of seeds with ABA at different concentrations showed that ABA (20 mg L-1) could effectively inhibit the seed germination.

      FQ-PCR Analysis on the Differential Expression of the Key Enzyme Genes Involved in Isoprenoid Metabolic Pathway in Allelopathic and Weak Allelopathic Rice Accessions (Oryza sativa L.) under Nitrogen Stress Condition
      WANG Hai-Bin;XIONG Jun;FANG Chang-Xun;QIU Long;WU Wen-Xiang;HE Hai-Bin;LIN Wen-Xiong
      Acta Agron Sin. 2007, 33(08):  1329-1334. 
      Abstract ( 1992 )   PDF (2162KB) ( 877 )   Save
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      The differential expression of the key genes controlling isoprenoid metabolism in allelopathic and weak allelopathic rice accessions was investigated under two nitrogen supply levels using fluorescence quantitative polymerase chain reaction(FQ-PCR). The results indicated that 12 detected key enzyme genes were mediated by lower nitrogen level. Of the twelve genes, six were up-regulated, and the others were down-regulated in allelopathic rice accession. In weak allelopathic rice Lemont, seven were up-regulated and five down-regulated. Of 12 tested genes, six up-regulated genes and five down-regulated genes detected in allelopathic rice PI312777 were founded in weak allelopathic rice Lemont. In other words, 11 out of 12 key genes involved in isoprenoid metabolic pathway in the two rice accessions had the same gene expression patterns under low nitrogen condition compared with the controls, suggesting that the related genes involved in isoprenoid metabolic pathway possessed the same or the similar ecological behavior in response to the changes of nitrogen supplies in the molecular scale. The further analysis showed that lower nitrogen supplies led to significantly declined expression of the key genes related to monoterpene, sesquiterpene, diterpene and triterpene. In conclusion, the increase of allelopathic potential induced by nutrient stress is not responsible for the variation of the terpenoid metabolism. It was also discussed that the relationships possibly existed among terpenoid synthesis decrease, hormone synthesis reduction and the plant growth inhibition, which in turn resulted in to a great extent, increased expression of the three genes encoding 3-hydroxy-3-methylglutaryl-CoA synthase, 3-hydroxy-3-methylglutaryl-CoA reductase and mevalonate kinase in the branch of mevalonate metabolism to sustain essential level of hormone for rice growth under nutrient stress condition.

      Enhancement of Drought and Salt Resistances in Tobacco by Transformation of Betaine Aldehyde Dehydrogenase Gene
      SI Huai-Jun;ZHANG Ning;WANG Di
      Acta Agron Sin. 2007, 33(08):  1335-1340. 
      Abstract ( 1883 )   PDF (1820KB) ( 1529 )   Save
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      Drought and salinity are the most important abiotic stresses affecting the normal growth and development of plants. One of the fundamental physiological mechanisms of higher plant to cope with environmental stresses is osmotic adjustment, and glycine betaine is one of the most important osmolytes. Glycine betaine is regarded as one of the most promising osmolytes because it possesses simple biosynthesis pathways, non-toxic to cells, and non-osmotic functions in stabilizing enzyme activities and membrane structures.
      In order to establish a glycine betaine biosynthetic pathway in glycine betaine-deficient crop plants through genetic engineering, which can enhance drought and salinity tolerances of crop plants, a betaine aldehyde dehydrogenase (BADH) gene which is the key gene for glycine betaine synthesis was isolated from spinach (Spinacia oleracea L.) (GenBank accession No.AY156694). The expression plasmid pBIBB was constructed by fusing the BADH gene with the constitutive promoter CaMV 35S. The transgenic tobacco plants were obtained by transformation of the expression plasmid pBIBB and mediation of Agrobacterium tumefaciens. PCR, Southern and Northern blot analyses indicated that the BADH gene has been integrated into genome of tobacco, transcribed and expressed in transgenic tobacco plants. The testing of BADH activity of transgenic plant leaves showed that the BADH specific activity ranged from 0.1 to 1.0 U mg-1, while it was not detectable in the control plants. The growth of the transgenic tobacco plants was normal and better than the untransformed plants under salt and polyethylene glycol (PEG) stresses. Plant height and fresh weight per plant of transgenic plant lines had a significant increase compared with those of untransformed control plants. This result proves that the BADH gene can express accurately in the exogenous transgenic plants and can be used in genetic engineering for plant drought and salt resistances.

      A Two-dimensional Gel Electrophoresis Protocol Suitable for Rice Microsome Proteins and the Analysis of Bentazon Tolerance-Related Proteins in Rice
      WANG Yun-Sheng;LU Xu-Zhong;WANG Zhi-Yong;SONG Feng-Sun;LI Li;YANG Jian-Bo
      Acta Agron Sin. 2007, 33(08):  1340-1345. 
      Abstract ( 1859 )   PDF (1955KB) ( 984 )   Save
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      Development of an appropriate two-dimensional gel electrophoresis (2-DE) technique for samples from various sources is important for proteomics study. Here, we report a modified 2-DE protocol suitable for rice microsomal proteins by using differential centrifugation in sample preparation, optimizing length and pH range of immobilized pH gradient (IPG) strips, and modifying the electrophoresis program. We used the 2-DE technique to detect the change of rice microsomal proteins expression induced by bentazon in Norin 8 (N8) as well as its bentazon sensitive lethal mutant Norin 8m (N8m). Results showed that 15 differentially expressed protein spots were found after bentazon treatment between or within the two lines. The proteins in these spots were classified into three types. TypeⅠ proteins showed differential expression between the two lines while typeⅡ proteins differed between the treated and untreated samples, and typeⅢ proteins were only induced in N8 after the treatment. TypeⅠ proteins arise from rice DNA damage by γ-ray radiation, based on the fact that N8m is a new strain from N8 mutated by γ-ray. Our previous study indicated that N8 and N8m showed no significant difference in the alteration of photosynthesis in the early stage after bentazon treatment, which induced accumulation of oxidative stress. It can be confirmed that typeⅡ proteins are related to the reactive oxygen scavenging system or systemic acquired resistance. The analysis of bentazon content change in 24 h indicated that N8 could metabolize the absorbed bentazon thoroughly while residual bentazon was present in the treated leaves of N8m. Therefore, we predict the typeⅢ proteins to be related to bentazon metabolism.

      Comparative Studies on Fiber Initiation Development of Four Cultivated Cotton Species
      LI Cheng-Qi;GUO Wang-Zhen;ZHANG Tian-Zhen
      Acta Agron Sin. 2007, 33(08):  1346-1351. 
      Abstract ( 1902 )   PDF (2341KB) ( 872 )   Save
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      Cotton is a fine natural fiber, an important textile, and a major industrial resource, accounting for nearly half of the world’s natural fiber consumption. Understanding the growth and development of cotton fibers is thus of global importance. Cotton fiber development is divided into four overlapping stages: fiber initiation, fiber elongation, secondary wall thickening, and maturation. The development of fiber initiation might include these aspects such as fiber cells differentiation, fiber protrusion, and initial elongation. At present, many studies on cotton fiber differentiation and development have been documented, but most of them are focused on Gossypium hirsutum, and the reports of comparative studies on fiber development among cotton species are ever less. Here we observed the ovules before and after anthesis of four cultivated cotton species including Gossypium hirsutum cv. Simian 3, Gossypium barbadense cv. Hai 7124, Gossypium arboreum cv. Dingyuan xiaohua, and Gossypium herbaceum cv. A1-50 by utilizing SEM (scanning electron microscope), and explored the influence of delay pollination on fiber initiation development of each cultivar. The results showed that under the climate conditions in the field at Nanjing, fiber cells protruded on the ovular surface in all cultivars except G. arboreum at 1 day before anthesis. At 0 and 1 day post-anthesis (DPA), fiber protrusion (or elongation) density of all materials was the highest at the funicular crest, higher at the chalazal cap and the middle part of ovule, and the least near the micropyle; moreover except upland cotton cultivar Simian 3, fiber density of the other three cultivars was lower at 1 DPA than that at 0 DPA, suggesting that with the expanding of the cotton ovular volume , the fiber "diluting" degree on the ovular surfaces was greater in G. barbadense, G. arboreum and G. herbaceum than in G. hirsutum. During cotton fiber initial stage, fiber density not only was affected by weather factors such as temperature but also related to the viability of stigma. Delay pollination exerted relatively significant influence on fiber initiation development of G. herbaceum, relatively less influence on G. barbadense, and the least influence on G. hirsutum and G. arboreum. Our studies might provide some theoretical references on understanding the mechanism of cotton fiber differentiation and growth, and exploring the phylogenetic relationships of fiber development of four cultivated cottons, as well as utilizing the heterosis of cotton fiber through artificial pollination.

      Analysis on the Correlation between Photosynthesis and Yield of the Leaves at Different Positions of Safflower
      GUAN Ling-Liang;WU Wei;ZHENG You-Liang;WANG Tao
      Acta Agron Sin. 2007, 33(08):  1352-1359. 
      Abstract ( 1711 )   PDF (2486KB) ( 921 )   Save
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      On fine days,photosynthetic characteristics of the leaves at different positions in three safflower varieties were monitored using portable LI-6400 photosynthesis system, and correlations between the net photosynthesis rate and the yield, agronomical characters were analyzed within 16 safflower varieties from 7 different countries. The results showed that maximum photosynthesis rate (Pnmax), light compensation point (LCP), light saturation point (LSP), dark respiration rate (Rd), apparent quantum yield (AQY) were in upper leaves > in middle leaves > in lower leaves. Light- photosynthesis curves indicated that the photosynthetic rate of all the leaves decreased significantly under the high light intensity except the upper leaves of PI 401470 and Chuanhong 1. And under the low light intensity, there was no marked difference between the photosynthetic rates of the leaves at the different positions. when the PFD exceed 400µmolm-2 s-1, the photosynthetic rate of the upper leaves was significantly higher than that of the lower ones. The diurnal variation pattern of photosynthesis was different in the leaves at the different positions and in different varieties , the time to the peaks and the value of the peaks were also different. The upper leaves of PI 401470 and Chuanhong 1 showed a single-peak curve, and the others showed a double-peak curve. Diurnal changes of the photosynthetically available radiation, air temperature, relative humidity, vapor pressure deficit and CO2 concentration in the air all showed a one-peak curve. The analysis of the upper leaves at flower bud stage showed that Pn had significant or highly significant positive correlations with flower yield per plant, 100-seed weight and the diameter of top fruitball. Safflower breeding for high photosynthetic efficiency would be an effective way for improving the yield.

      Growth Dynamics and Optimum Harvest Period of a Novel Forage Maize
      REN Yong;CHEN Rou-Yi;TANG Qi-Lin;RONG Ting-Zhao
      Acta Agron Sin. 2007, 33(08):  1360-1365. 
      Abstract ( 1930 )   PDF (1745KB) ( 1005 )   Save
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      Forage maize (Zea mays×Z. perennis) is a new type of perennial forage grass bred by maize-perennial teosinte substitution line (2n=20) and Z. perennis (2n=40). It can be harvested for silage or green feed several times in one growth period, and has high nutritive value, regenerative ability, and environmental adaptation. To understand the growth regularity and confirm the best harvest time of forage maize, its growth rate, fresh and dry matter accumulation and distribution during different stages in a field experiment were investgated, and evaluated its nutient values. The results indicated that the dynamic growth of forage maize fits Logistic model, and the growth rate was slow from the 30th to 50th day after sowing, fast from the 51st to 70th day (4.4 cm d-1), slow from the 71st to 90th day, fast from the 91st to 110th day, and slow after 111st day (productive stage). Biomass and the ratio of stem to leaf of forage maize increased while palatability and nutritive value declined from tillering to silking stages. After tasseling stage, the nutrient value declined faster. Gross energy (GE), digestible energy (DE), metabolizable energy (ME), and total digestible nutrient (TDN) were the highest at booting or initial tasseling stage, which were 18.5 MJ kg-1, 12.2 MJ kg-1, 10.0 MJ kg-1, and 0.66 kg, respectively. At initial tasseling stage, the fresh and dry matter yields were 101.4 t ha-1 and 18.35 t ha-1, crude protein (CP), crude fiber (CF), ether extract (EE), crude ash (CA) and nitrogen-free extract (NFE) were 14.2%, 24.3%, 3.9%, 6.3%, and 51.3%, respectively. It is suggested that forage maize should be harvested in initial tasseling stage in order to produce better biomass and nutritive value.

      Filling Properties of Grains on Different Positions in a Panicle of Rice with Different Panicle Types
      WANG Jia-Yu;FAN Shu-Xiu;XU Zheng-Jin;CHEN Wen-Fu
      Acta Agron Sin. 2007, 33(08):  1366-1371. 
      Abstract ( 2184 )   PDF (2101KB) ( 1079 )   Save
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      Plant type improvement is one of the important methods in rice super high yield breeding, and the erect panicle type is core target of northern japonica rice plant type improvement. The filling properties of grains on different positions in 5 panicle types of rice cultivars were studied in this experiment with a randomized block design, and the data were simulated and analyzed with Richards equation W=A/(1+Be-bt)1/N. The results indicated that for a erect panicle cultivar, the filling of the secondary branch grains at the middle and basal parts was significantly inhibited by the primary branch grains at the upper and middle parts because the big erect panicle varieties have more spikelets than those of curved panicle varieties. The grain filling peak value of the secondary branch grains at middle and basal parts in erect panicle cultivar Shennong 265 was smaller, and the time to peak value was later. The maximum filling rate in basal secondary branch grains was about half of that in upper primary branch grains, and the time to maximum filling rate was 10 d later, but after that time the filling rate slowed down, and the dynamic curve of grain weight was close to the linearity, at last the grain weight was also close to that of other positions. When the grains per panicle and grain density of erect panicle cultivars reached to 170 grains/panicle and 10 grains/cm, respectively, there was obvious difference in grain filling of different grain positions between big erect and semi-erect panicle types of rice cultivars, but the middle and basal secondary branch grains could finish normal grain filling, suggesting that erect panicle type cultivars can overcome the negative effect from increased grains/panicle and grain density on a certain extent, which is an important physiological basis for yield potential increase. As for the curved panicle cultivars, the primary branch grains at the upper and middle parts mainly inhibited the middle secondary branch grains in a panicle, and the influence was less than that of the erect panicle cultivars.

      RESEARCH NOTES
      Distribution of Grain Hardness and Puroindoline Alleles in Landraces, Historical and Current Wheats in Shandong Province
      LI Gen-Ying;XIA Xian-Chun;HE Zhong-Hu;SUN Qi-Xin;HUANG Cheng-Yan
      Acta Agron Sin. 2007, 33(08):  1372-1374. 
      Abstract ( 1850 )   PDF (1091KB) ( 978 )   Save
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      Studies on the grain hardness and puroindolines alleles in wheat cultivars released in different historical periods, are helpful for breeding wheat cultivar with optimal endosperm texture. In the present study, 523 accessions from Shandong Province including 431 landraces, 63 historical cultivars and 29 current cultivars were used to evaluate the SKCS hardness and distribution of puroindoline alleles (Pins). Distribution of grain hardness differed in landraces, historical cultivars and current wheats, with 75.6%, 20.4%, and 3.9% of hard texture, and 20.4%, 19.0%, and 13.8% of mixed wheats, and 3.9%, 68.3%, and 58.6% of soft grains, respectively. Six genotypes of Pina and Pinb were present in landraces, in which Pina-D1a/Pinb-D1p and Pina-D1b/Pinb-D1b were the dominant genotypes, accounting for 38.0% and 59.6% of hard wheat, respectively. Compared with landraces, the polymorphism of Pina and Pinb was decreased in historical cultivars. Pina-D1b/Pinb-D1a, Pina-D1a/Pinb-D1b, and Pina-D1a/Pinb-D1p accounted for 37.5%, 37.5%, and 25.0% of hard wheat, respectively, whereas, Pina-D1a/Pinb-D1b was the only genotype presented in hard genotype of current cultivars surveyed. A novel Pinb allele with double mutations at the positions of 96th (C to A) and 265th (deletion of A) was found in three landraces, and was designated as Pinb-D1aa.

      Difference in Diurnal Variations of Primary Photochemical Reactions in Maize Leaves Grown in Different Directions
      XU Zhen;LI Peng-Min;GAO Hui-Yuan;DONG Shu-Ting;WANG Kong-Jun;ZHANG Ji-Wang
      Acta Agron Sin. 2007, 33(08):  1375-1379. 
      Abstract ( 1875 )   PDF (1347KB) ( 956 )   Save
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      Diurnal variations of primary photochemical reactions in maize (Zea mays L.) leaves grown in different directions were etudied by chlorophyll a fluorescence transient measurement and the relevantly analytical method, JIP-test on sunny day. The results showed that in the forenoon, the performance index on a basis of absorption (PIABS) and maximum quantum efficiency of PSⅡ (φPo) decreased more drastically, suggesting the severe photoinhibition in the leaves orienting to west. However, the photoinhibition was more severely in the leaves orienting to east in the afternoon. With the variation of photon flux density (PFD), ratio of variable fluorescence Fk to the amplitude Fj-Fo (Wk) increased firstly, then followed by a decrease in the two group leaves. In addition, efficiency that a trapped exciton can move an electron into the electron transport chain beyond QA- (Ψo) hardly varied in the leaves orienting to east, whereas that in the leaves orienting to west decreased firstly, then followed by an increase. These results demonstrate that the donor and acceptor sides of PSⅡ were damaged differently in the leaves orienting to different directions. Dissipation per excited cross-section or per active reaction center indicates that the excessively excited energy per cross-section or per active reaction center was higher in the leaves orienting to west at noon while that was higher in the leaves orienting to east in the afternoon. Our results also exhibited that compared with φPo, other parameters derived from JIP-test such as PIABS, are more sensitive to the variation of PFD and can reflect degree of photoinhibition in maize leaves in more detail. When studying diurnal variations of photoinhibition in plant leaves, much attention should be paid on the selection for growing direction of leaves.

      Preliminary Identification of Genetic Overlaps between Sheath Blight Resistance and Drought Tolerance in the Introgression Lines from Directional Selection
      ZHENG Tian-Qing;XU Jian-Long;FU Bing-Ying;GAO Yong-Ming;Satish VERUKA;Renee LAFITTE;ZHAI Hu-Qu;WAN Jian-Min;ZHU Ling-Hua;LI Zhi-Kang
      Acta Agron Sin. 2007, 33(08):  1380-1384. 
      Abstract ( 2372 )   PDF (1761KB) ( 914 )   Save
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      With the combination of advanced backcrossing and artificial directional selection for yield under drought stresses at rain-fed lowland and upland, sixty-five BC2 introgression lines (ILs) with two relatively uniformed genetic backgrounds (IR64 and Teqing) and two donors with relatively good drought tolerances (BG300 and BG304) were developed and assayed with SSR makers. Using this set of materials, SBR was identified by artificial inoculations of R. solani from fields at Philippines belonging to the AG-1 group. Lengths of all lesions (TLL) from 5 randomly selected tillers per hill were measured. Analysis of genetic overlap between SBR and DT was carried out at two levels. First is the phenotypic analysis for SBR of the DT ILs from directional selection, in which the recurrent parents (RP) were used as the control and the ILs behaved better in yield were selected under the stress when the RP were almost killed and had not seed. The Teqing DT ILs tended to be decreased in SBR due to the selective introgression comparing with their RP, which showed medium resistance (MR) in our test; while the IR64 DT ILs tended to be increased in SBR comparing with IR64, which represented medium susceptibility (MS) in the same test. This kind of purge caused by directional selection indicated the possible correlation of DT with SBR in this set of ILs at the phenotypic level. The sencond is the genomic region overlaps detected by ANOVA and excessive introgression. Besides the underestimates by ANOVA of SBR loci, a total of six loci were found to be associated with SBR in DT ILs and five of them matched the 7 of the 26 loci reported previously by other researchers. Among the 6 loci, QSbr10 was detected for the same donor alleles in both backgrounds, while QSbr6 was detected for different donor alleles in different backgrounds; three loci (QSbr6, QSbr8, and QSbr10) overlaped the DT loci detected with the same ILs in our previous study.

      Effects of Phosphorus Nutrient on the Photosynthetic Characteristics in Rice Cultivars with Different Cold-Sensitivity
      WANG Guo-Li;GUO Zhen-Fei
      Acta Agron Sin. 2007, 33(08):  1385-1389. 
      Abstract ( 1844 )   PDF (1784KB) ( 1435 )   Save
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      The experiment was conducted under low temperature using two rice cultivars with different cold sensitivities grown in cultured solution with different phosphorus concentrations. The result showed that chlorophyll content, photosynthetic rate, Fv/Fm and qp were decreased in the two rice cultivars under chilling stress, and they were decreased more in chilling sensitive cultivar than in chilling tolerant cultivar. The seedlings cultured in higher level of phosphorus nutrient had higher levels of chlorophyll, photosynthetic rate, Fv/Fm and qp. Phosphorus deficiency reduced the chlorophyll content, photosynthetic rate, Fv/Fm and qp. NPQ under chilling stress and phosphorus deficiency was increased in chilling tolerant cultivar, but not changed much in the chilling sensitive cultivar. The results indicated that photosynthesis and the chilling resistance of rice can be improved by exogenous application of phosphorus. Phosphorus nutrition status had a more significant effect on the photosynthesis in chilling-sensitive cultivar than in chilling-tolerant cultivar.

      Thermostability of PhotosystemⅡ in Low Chlorophyll b Rice Mutant
      GUO Chun-Ai;ZHOU Wei;LIU Fang;XU Xiao-Ming
      Acta Agron Sin. 2007, 33(08):  1390-1392. 
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      Low chlorophyll b rice mutant and the wild type rice (Zhenhui 249) were used to study the effects of low chlorophyll b on thermostability of photosystemⅡ in mutant by measuring their changes in chlorophyll fluorescence parameters and polyphasic chlorophyll fluorescence transients under different temperature treatments. The results showed that the temperature of Fo rising threshold was shifted 3℃ lower in the mutant (43℃) than in the wild type (46℃). At temperature up to over 40℃, O-J-I-P transient was transformed into O-K-J-I-P transient, a very clear K point appeared, this suggested that high temperature damaged the oxygen evolving complex (OEC), and the degree of damage was severer in mutant than in the wild type. In addition, high temperature led to inactivation of PSⅡ reaction centre. All results indicated that the mutant showed a tendency for higher thermosensitivity, and the decrease of chlorophyll b in LHCII could lead to less thermostability of PSⅡ structure and function.

Co-sponsored:
the Crop Science Society of China
the Institute of Crop Science, CAAS
China Science Publishing & Media Ltd.
Published: Science Press
Editor-in-chief: Wan Jian-min
Associate Editors-in-Chief:
Chen Xiao-ya Yang Jian-chang Zhang Xian-long Wang Jian-kang Xu Ming-liang Liu Chun-ming Wang Dao-wen Sun Chuan-qing Ding Yan-feng Jin Wei-wei Chu Cheng-cai Cheng Wei-hong
Director of the editorial department:
Yan Chun-ling
CN 11-1809/S
ISSN 0496-3490
Post subscription code: 82-336

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  • Started in 2013
  • Covered by SCIE
  • Open access in ScienceDirect

Editor in chief: Wan Jian-min
CN 10-1112/S
ISSN 2095-5421, 2214-5141(online)
Online published:
https://www.sciencedirect.com/journal/the-crop-journal
Submission: https://www.editorialmanager.com/cj/
E-mail: cropjournal@caas.cn
Tel: 8610-82108548

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