Table of Content

12 August 2012, Volume 38 Issue 08

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Genetic Analysis and Gene Mapping of Early Senescence Leaf Mutant esl2 in Rice

XU Fang-Fang,SANG Xian-Chun,REN De-Yong,TANG Yan-Qiang,HU Hong-Wei,YANG Zheng-Lin,ZHAO Fang-Ming,HE Guang-Hua

Acta Agron Sin. 2012, 38(08):  1347-1353.  doi:10.3724/SP.J.1006.2012.01347

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An early senescence leaf mutant temporarily designated as esl2was discovered in the progeny of an excellent indica restorer line Jinhui 10 with seeds treated by ethyl methane sulfonate (EMS). Themutant kept normal at seedling stage and showed etiolated senescence leaves from booting sage to the maturity, especially at tip and margin of leaf blade. By contrast with the wild type, photosynthetic pigment contents decreased significantly at both booting stage and heading stage, superoxide dismutase (SOD) activity and soluble protein contents decreased significantly, while the activities of peroxidase (POD) and catalase (CAT), and contents of reactive oxygen species (ROS), malondialdehyde (MDA) and praline increased significantly at heading stage in the esl2 mutant. The assay of Transmission Electronic Microscope (TEM) observation was performed and demonstrated that the most cells appeared irregular and void with endolysis and disrupted organelles at senescence part of the mutational leaf, concomitantly, abnormal chloroplast appeared and showed dissolved membrane, indistinct grana, disorganized lamellar structure and incorrect thylakoid. Genetic analysis suggested that the mutational trait was controlled by one nuclear recessive gene. Xinong 1A was crossed with the esl2 and 1005 mutational F₂single plants were used for gene mapping. Finally, Esl2 locus was mapped between SSR marker RM17122 and swu4-13 on the chromosome 4 with physical distance of 244 kb. This result provides a foundation of Esl2 gene cloning by map-based strategy as well as its functional analysis.

Isolation and Expression Patterns of TaPHYA Gene Subfamily in Common Wheat

WANG Xia,MA Yan-Bin,MENG Fan-Hua,LI Xiu-Quan,YANG Li,Wu-Xia,YANG Ke-Cheng,YANG Jian-Ping

Acta Agron Sin. 2012, 38(08):  1354-1360.  doi:10.3724/SP.J.1006.2012.01354

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Phytochromes (PHYs) are important genes relating to crop agronomic traits. In this paper, TaPHYA1, TaPHYA2, and TaPHYA3 were cloned fromcv. Chinese Spring(Triticum aestivum L.). Theputative domains ofTaPHYA1, TaPHYA2, and TaPHYA3 proteins were predicted via the NCBI Protein BLAST. Either TaPHYA1 or TaPHYA3 was composed of a GAF domain, a PHYtochrome domain, two PAS domains, a His Kinase A domain, and a Histidine kinase-like ATPase domain.Phylogenetic tree analysis indicated that TaPHYA1, TaPHYA2, and TaPHYA3 were closer to PHYA members of monocot plants (ZmPHYA, SbPHYA, and OsPHYA) rather than to those of dicot plants (AtPHYA and GmPHYA). Expression levels of TaPHYAs were analyzed using semi quantitative RT-PCR and real time PCR assays.Tissue-specific expression of total TaPHYA was also detected in stem, leaf, and spike,whose levelswere 1.35, 0.34, and 0.87 times of that in root. Additionally, TaPHYA showed high expression level in darkness, far-red, and blue light conditions, but low expression level in red and white light conditions. The transcription level of TaPHYA in the seedlings grown in the darkness or under far-red light was four or three times of that in seedlings grown in red light, respectively.

Chromosomal Localization of Transcription Factors in Gossypium hirsutum

LI Li,WANG Shun-Feng,LIU Fang,TANG Shi-Yi,TAN Zhao-Yun,ZHANG Jian,TENG Zhong-Hua,LIU Da-Jun,ZHANG Zheng-Sheng

Acta Agron Sin. 2012, 38(08):  1361-1368.  doi:10.3724/SP.J.1006.2012.01361

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A total of 1 455 SSR primer pairs designed from 1 116 Gossypium hirsutum transcription factor DNA sequences in Plant Transcription Factor Databases (PTFD) were used to screen the polymorphic primers between upland cotton cultivars/lines Yumian 1, 7235, CCRI35, and T586. A total of 66 pairs of polymorphic primers were obtained, which are related to 64 transcription factors among 27 transcription factor families. The polymorphic primers included 23 pairs between yumian1 and CRI35, 30 pairs between Yumian 1 and T586, and 33 pairs between Yumian 1 and 7235. Sixty-six polymorphic primer pairs were used to genotype the corresponding recombinant inbred line populations, and 93 loci were obtained, including 23 loci in population (Yumian 1×CRI35) F_2:6, 32 loci in population (Yumian 1×T586) F_2:7, and 38 loci in population (Yumian 1×7235) F_2:6. The transcription factor SSR loci, together with other SSR loci which have already been mapped on upland cotton linkage map in our laboratory, were used to conduct genetic linkage analysis, and 84 loci were mapped on 23 chromosomes, including 32 loci on A genome and 52 on D genome.

Construction of Genetic Map and Analysis of QTLs for Grain Weight Using a RIL Population Derived from Shannong 01-35 × Gaocheng 9411

HI Cui-Lan,ZHENG Fei-Fei,CHEN Jian-Sheng,HAN Shu-Xiao,WANG Yong-Rui,TIAN Ji-Chun

Acta Agron Sin. 2012, 38(08):  1369-1377.  doi:10.3724/SP.J.1006.2012.01369

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The objectives of this study were to construct a new linkage map of wheat using a recombinant inbred line (RIL) population derived from the cross between Shannong 01-35 and Gaocheng 9411 and locate quantitative trait loci for thousand-grain weight (TGW) using this map. The RIL population, consisting of 182 lines, was obtained via single-seed descendent method until the F₈ generation. The genetic map consisted of one TaGW2-CAPS,59 SSR, and442 DArT markers in 29 linkage groups, including 54 novel markers (44 DArT markers and 10 SSRs) assigned into 18 linkage groups. The total genetic length of the map was 4084.5 cM with an average interval distance of 8.13 cM. The 182 RILs and their parents were grown in four environments from 2008 to 2010, and QTLs associated with TGW were identified using mixed linear model based on both separated and joint environments. A total of seven QTLs were detected including three QTLs (QGW4B-7, QGW5B-20, and QGW6A-29) commonly found using both methods. Three major QTLs, i.e., QGW4B-7, QGW5B-12, and QGW6A-29, exhibited phenotypic contributions higher than 10%. These results suggest that the QTLs detected by using the successfully constructed genetic map are valuable in molecular marker-assisted selection in wheat.

Development and Cytogenetic Analysis of Perennial Wheat in Cold Region

ZHAO Hai-Bin,ZHANG Yan-Ming,SHI Chun-Long,YAN Xiao-Dan,TIAN Chao,LI Yong-Peng,LI Ji-Lin

Acta Agron Sin. 2012, 38(08):  1378-1386.  doi:10.3724/SP.J.1006.2012.01378

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The morphology of the progeniesfrom octoploid Trititrigia ´ Thinopyrum intermedim and their chromosomal behaviours during meiosis were observed to provide therotical and material bases for developing perennial wheat. The seed-setting rate of contemporary hybrid was 10–39%, and the F₁ plants showed an intermediate type of parents with perennial characteristic and resistance to multiple diseases. During the second and third growing year, the F₁ plants produced a small amount of seeds with setting rate of 2–3%. The F₂ plants separated complexly, which involved the types of Tritielytrigia and Thinopyrum intermedium. The F₃ and F₄ generations tended to produce some types of common wheat but with perennial characteristics, such as rich tillers, prolific spikelets, and resistances to diseases and coldness. In F₁ generation, 49 chromosomes were observed in root tip cells, which formed 14–17 bivalents and 4–21 univalents at metaphase of meiosis I. In F₂ and F₃ generations, the numbers of bivalent and univalent at meiosis were 14–21 and 9–17, respectively. Seed-setting rate of the perennial hybrids was recovered with the increase of generation, and the F₁ plants could survive in natural environment for five years. We have obtained four perennial wheat lines in forage type from the F₄ generation. These lines showed tall plant height (140 cm), abundant tillers (more than 60), rich spikelets (25–30), resistance to multiple diseases, tolerance to coldness, and high regenerative capability after harvest. Besides, some common wheat-type perennial lines were also attractive, which requires further improvement.

Genetic Diversity of Peanut Landraces in Guizhou Province

LIN Mao,LI Zheng-Qiang,ZHENG Zhi-Hong,Lü Jian-Wei,MA Tian-Jin,LI Chao,KAN Jian-Quan

Acta Agron Sin. 2012, 38(08):  1387-1396.  doi:10.3724/SP.J.1006.2012.01387

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In order to assess the genetic diversity of peanut in Guizhou province and provide a theoretical basis for breeding, 68 accessions of peanut landracescollected from Guizhou province were evaluated by 50 SSR markers. Seventy-nine alleles were amplified by forty-one polymorphic SSR primer pairs. The average number of alleles per locus was 1.93 with a range from 0.045 to 0.951. Total Shannon information index per locus varied widely from 0.2518 (PM79) to 0.6826 (PM188) with an average value of 0.5268; total Nei’s genetic diversity index per locus varied widely between 0.1699(PM79) and 0.4995 (PM188) with an average value of 0.3556. Cluster analysis with UPGMA showed that the landraces could be divided into two groups and the genetic relationship among materials with similar seed sizes was not in accord with their geographical origins. The peanut landrace in Guizhou showed higher genetic diversity.

Map-Based Cloning of a Green-Revertible Albino and High-Tillering Dwarf Gene hw-1(t) in Rice

GUO Tao,HUANG Yong-Xiang**,HUANG Xuan,LIU Yong-Zhu,WANG Hui,ZHANG Jian-Guo,CHEN Zhi-Qiang,WANG Hui

Acta Agron Sin. 2012, 38(08):  1397-1406.  doi:10.3724/SP.J.1006.2012.01397

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In this study, the green-revertible albino and high-tillering dwarf gene hw-1(t) was fine mapped with a 24.9 kb physical distance between two InDel markers, HW36 and HW7 on chromosome 5, where five open reading frames were predicted. Sequencing and restriction enzyme digestion analysis revealed hfa-1 mutant carried a single nucleotide substitution (G→A) in the putative gene LOC_Os4g57320, which resulted in a premature stop codon. Therefore, we deduced that LOC_Os4g57320 is hw-1(t). BLAST analysis indicated that hw-1(t) exits as a single copy in rice genome. Sequence alignment revealed that hw-1(t) was highly homologous to AtIM and SiPTOX, except some variation on transcript and protein structure. Gene expression analysis indicated HW-1(t) was constitutive gene, which did not be affected by light.

Mapping of Quantitative Trait Loci Underlying Six Agronomic Traits in Flue-Cured Tobacco (Nicotiana tabacum L.)

TONG Zhi-Jun,JIAO Fang-Chan,WU Xing-Fu,WANG Feng-Qing,CHEN Xue-Jun,LI Xu-Ying,GAO Yu-Long,ZHANG Yi-Han,XIAO Bing-Guang,WU Wei-Ren

Acta Agron Sin. 2012, 38(08):  1407-1415.  doi:10.3724/SP.J.1006.2012.01407

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Studies of genetic mapping of quantitative trait loci (QTLs) in tobacco have still been very limited up to date due to the difficulty of molecular marker development and genetic map construction in this species. In this study, with a doubled haploid (DH) population of flue-cured tobacco and a genetic map consisting of 611 SSR markers on 24 linkage groups (LGs) and spanning a total length of 1 882.1 cM constructed based on this population, QTL mapping was performed using the method of composite interval mapping for six agronomic traits related to leaf yield, including plant height (PH), stem girth (SG), internode length (IL), leaf number (LN), length of the largest waist leaf (LWL) and width of the largest waist leaf (WWL). A total of 69 QTLs were detected. Most of the QTLs had small effects, but there were four with relatively large effects, explaining 15–20% of the phenotypic variation in the DH population. The six traits were largely correlated with each other. Consistent with this, many small regions harboring two or more closely linked QTLs of different traits were found in the genome.

Phenotypic Analysis and Molecular Characterization of Two Allelic Mutants of the Dwarf18 Gene in Rice

HOU Lei,YUAN Shou-Jiang,YIN Liang,ZHAO Jin-Feng,WAN Guo-Feng,ZHANG Wen-Hui,LI Xue-Yong

Acta Agron Sin. 2012, 38(08):  1416-1424.  doi:10.3724/SP.J.1006.2012.01416

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We identified two strong dwarf mutants from Nipponbare by EMS mutagenesis, designated as s2-9 and s1-146a. The plant height of these two mutants was 26.3% and 19.2% of that of Nipponbare at the mature stage. They also had wider and dark green leaf at seedling stage. The GA₃ treatment of seedling and α-amylase activity analysis in endosperm showed that the mutated gene was involved in GA biosynthesis. Fine mapping showed that the mutant phenotype was tightly linked with the d18 locus. There was a single nucleotide substitution at the 3'-splicing site between the first intron and the 2nd exon in s2-9, whereas there was a single nucleotide substitution in the 2nd exon in s1-146a, which caused a premature stop codon. Semi quantitative RT-PCR revealed that transcript of the D18 gene was up-regulated in s1-146aas compared with WT, but was not detected in s2-9.

Genetic Diversity and Evolutionary Analysis of Tobacco (Nicotiana tabacum L.) Germplasm Resources Based on ISSR and SRAP Markers

QI Jian-Min,LIANG Jing-Xia,CHEN Mei-Xia,XU Jian-Tang,NIU Xiao-Ping,ZHOU Dong-Xin,WANG Tao,CHEN Shun-Hui

Acta Agron Sin. 2012, 38(08):  1425-1434.  doi:10.3724/SP.J.1006.2012.01425

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In order to explore on the genetic diversity and genetic evolution among cultivated types and wild species in the genus Nicotiana, 96 tobacco accessions from China and abroad were studied with ISSR and SRAP analysis. Both molecular markers revealed high genetic diversity among species of Nicotiana (genetic similarity = 0.28–0.58) and low genetic diversity among 91 cultivated tobacco lines (Genetic Similarity = 0.61–0.99).Genetic differentiation index (GST) among species of Nicotiana was 0.83. The order of genetic diversityindex within different cultivated types was cured tobacco>suncured tobacco>burley tobacco>aromatic tobacco. When the similarity coefficient was 0.67 as the cutting line, the cluster results of 96 tobacco accessions based on SRAP and ISSR were as follows: (1) UPGMA analysis showed that all 91 culture varieties clustered into one group separating from N. rustica, N. glutinosa, N. repanda, N. gossei, N. suaveolens. (2) The cured tobacco has close genetic relationship with suncured tobacco, and aromatic tobacco was far away from N. rustica. There was little genetic differentiation between cultivated tobacco lines from China and those from othercountries. (3) The correlation coefficient between genetic distance matrixes based on ISSR and SRAP was 0.68, indicating that the basic results of the two types of markers are consistent. In conclusion, ISSR and SRAP are efficient in generating more accurate information on genetic background, relationship and evolution of tobacco germplasm. The results of this research would be favorable for further practices in tobacco breeding.

QTL Analysis of Tassel-Related Traits in Maize (Zea mays L.) Using Multiple Connected Populations

YANG Zhao-Zhao,LI Yong-Xiang,LIU Cheng,LIU Zhi-Zhai,LI Chun-Hui,LI Qing-Chao,PENG Bo,ZHANG Yan,WANG Di,TAN Wei-Wei,SUN Bao-Cheng,SHI Yun-Su,SONG Yan-Chun,WANG Tian-Yu,LI Yu

Acta Agron Sin. 2012, 38(08):  1435-1442.  doi:10.3724/SP.J.1006.2012.01435

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Maize tassel-related traits are of importance to maize production. QTLs for three tassel-related traits were mapped in 11 RIL populations with the common parent “Huangzaosi” under a single environment and across environments to understand genetic basis of maize tassels. Meanwhile, epistasis among QTLs and QTL by environment interactions (QEI) was analyzed. Totally 15 major constitutive QTLs were detected in at least five environments. Particularly, two constitutive QTLs were detected in bin 3.04 in the Qi 319 and Lü 28 populations, which had an overlapping interval of 226.0–230.1 on the IBM 2008 Neighbors map, with a quite high phenotypic variance explained, and the mean R² of 17.4% and 14.4%, respectively. A total of 21 common QTLs were detected in more than two populations, of which five on chromosome 2, 3, 6 and 8 were found in three populations. The QTLs stably expressed under different environments or genetic backgrounds may play an important role in controlling maize tassel-related traits, and be used at the candidates for fine mapping and positional cloning.

Development and Evaluation of New Non-Redundant EST-SSR Markers from Gossypium

WANG Wei,WANG Chang-Biao,LIU Fang,CHEN Hao-Dong,WANG Lin,WANG Chun-Ying,ZHANG Xiang-Di,WANG Yu-Hong,WANG Kun-Bo

Acta Agron Sin. 2012, 38(08):  1443-1451.  doi:10.3724/SP.J.1006.2012.01443

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A software Clustal X was used to analyse the redundancy of 393 753 ESTs of Gossypium available in public database. By mining 349 815 non-redundant ESTs, a total of 11 372 SSR loci derived from 10 507 ESTs using a software SSRmine developed by ourselves were observed. The frequency of ESTs containing SSRs was 3%, with an average of one SSR in every 21 kb of EST sequence. Besides, trinucleotide and hexanucleotide repeats were found to be the most abundant among 2–6-nucleotide repeat types, accounting for 34.1% and 40.6% respectively. In dinucleotide repeats, trinucleotide repeats, tetranucleotide repeats, pentanucleotide repeats and hexanucleotide repeats, AG/CT, AAG/CTT, AAAT/ATTT, AAAAG/CTTTT, AAAAAG/CTTTTT motifs accounted for the highest proportion respectively. Two hundred pairs of new non-redundant EST-SSR primers were developed based on 410 EST sequences removed the redundancy which have not been developed so far in Gossypium arboreum L.,G. hirsutum,and G. barbadense. Andwe used a software SSRmine developed by ourselvesto obtain non-similarity primers, designated CRI (Cotton Research Institute) XXX through six steps, including SSR primer sequences download, pretreatment, Blastn, extraction of primer numbers of similarity score more than 81%, extraction of redundant primers pairs and making redundant primers in a line, to remove homologous sequences from themselves and similar primers released in CMD from different cotton species. Among them, 100 primers were evaluated in polymorphism information content (PIC) and transferability using twelve cotton species including seven representative diploids species and five tetraploid species. The results showed that a total of 56 from the 100 pairs of SSR primers could be amplified the stable and clear polymorphic bands in the 12 accessions mentioned above, moreover, 35 out of 56 pairs of primers were polymorphic, with the primer polymorphism ratio of 35%. PIC of these primers ranged from 0.097 to 0.888, with the average of 0.482. Totally, the transferability among twelve cotton species was 100% for a pair of EST-SSR primers from Gossypium barbadense L., 81% for 25 primers from G. arboreum and 80.1% for 74 primers from G. hirsutum, respectively.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of Diffuse and Direct Lights on Photosynthetic Function in Sorghum Leaf

WANG Xiao-Lin,LI Zhi-Qiang,JIANG Chuang-Dao,SHI Lei,XING Quan,LIU Li-An

Acta Agron Sin. 2012, 38(08):  1452-1459.  doi:10.3724/SP.J.1006.2012.01452

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The effects of direct and diffuse lights on the leaf-side-specific regulation of photosynthesis were studied in sorghum, a typical C₄ plant. Leaf morphology and structure were carefully investigated by semithin cross section of sorghum leaves. Leaf absorption, transmittance and reflectance profiles were similar on the adaxial and abaxial leaf surfaces across the light spectrum from 400 to 800 nm, whether light was illuminated via the adaxial or abaxial surface. The photosynthetic light-response curves showed that maximal whole photosynthetic rates were higher when the light entered the leaf via the adaxial surface than the abaxial surface. The changing trend of stomatal conductance was similar with photosynthetic light-response curves. However, the maximal photosynthetic rates were much lower when the light entered the leaf via the abaxial surface than adaxial surface when blocking the stomata of light-oriented side by PE membrane. Theintensity of direct and diffuse lights varied widely in a day, and that of diffuse light was significantly lower than light compensate point (I_c) of abaxial leaf surfaces in sorghum. Consequently, photosynthetic rate of abaxial leaf surface in sorghum should be mainly droved by self-transmitted light but not diffuse light. Differences in stomatal density, substomatic cavity, contacting areas between bundle sheath and mesophyll cells are related to this feature of abaxial leaf surfaces. is the findings of the present study are important for field management, investigation of ecosystem productivity and breeding for high photosynthetic efficiency.

Effect of Panicle Nitrogen Fertilizer Management on Yield and Population Quality in Mechanical Transplanted Super Rice Ningjing 1 with Different Seedling Ages

HUO Zhong-Yang,WEI Hai-Yan,ZHANG Hong-Cheng,GONG Zhen-Kai,DAI Qi-Gen,XU Ke

Acta Agron Sin. 2012, 38(08):  1460-1470.  doi:10.3724/SP.J.1006.2012.01460

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Adopting super high yield rice Ningjing 1 as material, the effect of panicle nitrogen fertilizer application time on yield and population quality of transplanted seedlings with different ages was studied. The results showed that, with the same panicle nitrogen fertilizer application time, rice yield, growth rate of rice population, dynamics of culm and tillers number, leaf area index and photosynthetic potential of right age seedlings were all better than those of overage seedlings in mechanical transplanted rice production. With the right age seedlings, when the panicle nitrogen fertilizer applied equally at the fourth leaf age from top and at the third leaf age from top (D4-3), rice yield, growth rate of population, percentage of productive tiller, leaf area index and photosynthetic potential after heading, leaf area of productive tillers at heading and its ratio, leaf area from flag leaf to the 3rd leaf from top of productive tillers at heading and its ratio, the drop angle of top three leaves were all higher than those when the panicle nitrogen fertilizer applied equally at the fifth leaf age from top and at the third leaf age from top (D5-3) or applied equally at the fifth leaf age from top and at the fourth leaf age from top (D5-4). With the overage seedlings, when the panicle fertilizer applied at D5-4, rice yield, growth rate of population from heading to maturing, dynamics of culm and tillers number and leaf area index after elongating, photosynthetic potential after the critical stage of productive tillers, leaf area of productive tillers and leaf area from flag leaf to 3rd leaf from top of productive tillers at heading, the length of basal three internodes of stem and its ratio to the whole stem were all higher than those when the panicle nitrogen fertilizer applied equally at the fifth leaf age from top and at the third leaf age from top D5-3 or applied at D4-3. The results indicated that seedling age is important for high yield of mechanical transplanted rice. Using right age seedlings is helpful for forming the high quality rice population and obtaining high yield when the panicle nitrogen fertilizer applied at D4-3. Instead, with the overage seedlings, the early applying of panicle nitrogen fertilizer, such as applying at D5-4, would promote some shaky tillers to be transformed into effective tillers and consequently form the ears, which provides a compensation for some insufficient growth due to transplanting with overage rice seedlings. However, the early applying of panicle nitrogen fertilizer would elongate the basal internodes of stem excessively and increase the risk of lodging.

Differential Expressions of the Proteins Related to Grain Filling between Superior and Inferior Spikelets of Super Rice after Anthesis

CHEN Ting-Ting,TAN Gui-Lu,CHU Guang,LIU Li-Jun,YANG Jian-Chang

Acta Agron Sin. 2012, 38(08):  1471-1482.  doi:10.3724/SP.J.1006.2012.01471

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Poor grain filling of the later-flowered inferior spikelets (in contrast to the earlier-flowered superior spikelets) is a serious problem in rice production. This problem is more aggravated in new bred super rice cultivars. To better understand the mechanism underlying the poor grain filling of inferior spikelets, we investigated the difference in expressions of the proteins related to grain filling in superior and inferior spikelets of two super rice cultivars, Liangyoupeijiu (indica hybrids) and Huaidao 9 (japonica) after anthesis through two-dimensional gel electrophoresis (SDS-PAGE) and the MALDI analysis. Results showed that the grain filling rate at 3–15 d after anthesis (DAA) and the final grain weight of inferior spikelets were much smaller than those of superior spikelets. The spots of protein expressed were fewer in inferior spikelets than in superior spikelets at 3, 8, and 15 DAA, and the results were reversed at 25 DAA. The spots of protein with two-fold expressions between superior and inferior spikelets showed a similar changing tendency. Twenty seven protein spots with significant difference in the expression between superior and inferior spikelets were chosen for the MALDI analysis, of which 14 protein spots were identified and their functions were analyzed. These proteins were involved in grain starch synthesis, protein synthesis, photosynthesis, energy metabolism, environmental adaptation and cell signal transduction. The results suggest that expression differences of the proteins related to grain filling account for the variation in grain filling between superior and inferior spikelets of rice.

Distribution Characteristics of Winter Wheat Yield and Its Influenced Factors in North China

LI Ke-Nan,YANG Xiao-Guang,LIU Yuan,XUN Xin,LIU Zhi-Juan,WANG Jing,Lü Shuo,WANG En-Li

Acta Agron Sin. 2012, 38(08):  1483-1493.  doi:10.3724/SP.J.1006.2012.01483

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APSIM-Wheat model was validated in regional level with crop data from agrometeorological observation stations in North China. Combining the daily climatic data during 1961–2007, the spatiotemporal distribution characteristics were analyzed in potential yield, water-restricted yield, and water-nitrogen-restricted yield of winter wheat to understand the influences of climatic factors on potential yield in different levels. The APSIM-Wheat model was proved to be applicable in North China. In the region, the potential yields of winter wheat in different levels showed a zonal distribution in space with a generally temporal decline; however, the differences of spatial distribution characteristics were distinct among yield levels. The decreasing trends were from northeast to southwest in potential yield of winter wheat, from southeast to northwest in water restricted yield, and from west to east before a decreasing from east to west in water and nitrogen restricted yield, with the maximum values in Jining, Shandong Province.Hebei Province was located in the zone of high values of potential yield and water and nitrogen restricted yield but low value of water restricted yield, where irrigation was the main factor to improve the yield of winter wheat. Shandong Province was in the zone of high values of potential yield and water restricted yield but low value of water and nitrogen restricted yield, where nitrogen fertilizer was the main factor to improve the yield of winter wheat. Henan Province was a zone of low value of potential yield, where radiation was a main restraint. The total radiation during the growing season was a major climatic factor that determined the spatiotemporal distribution characteristics of the simulated potential yield of winter wheat, and it was positively correlated with the potential yield (P < 0.01). Precipitation during the growing season was the most important climatic factor for distribution characteristics of water restricted yield, which was positively correlated with water restricted yield (P < 0.01). In contrast, the variance of water and nitrogen restricted yield explained by climate factors was only 0.48, suggesting that soil factors were determinative rather than climatic factors. Under the background of changed climate and unchanged varieties of winter wheat, the potential yields at different levels showed declining trends which resulted from the decrease of radiation and the increase of accumulated temperature during wheat growing season. The primary climatic factors for determining the distribution characteristics of winter wheat yield were total radiation and precipitation.

Effects of Slow-Release Urea Combined with Conventional Urea on Rice Output and Growth in Soils of Different Textures

ZHANG Xiao-Cui,DAI Qi-Gen,HU Xing-Xing,ZHU De-Jian,DING Xiu-Wen,MA Ke-Qiang,ZHANG Hong-Cheng,ZHU Chong-Chong

Acta Agron Sin. 2012, 38(08):  1494-1503.  doi:10.3724/SP.J.1006.2012.01494

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Public attentions have been increasingly paid to the slow-release fertilizer (sulfur-coated urea, or SCU) which has developed quickly during the last decade. In this research, a field experiment with 270 kg ha^-1 N fertilizer application was conducted in two kinds of soil (sandy soil and clay soil) using the early maturing late japonica variety Nanjing44 as materials. The effects of fertilizing with sulfur-coated urea alone and mixing application of SCU and conventional urea (PU) on grain yield and plant growth were examined and compared. Results showed that compared with the treatment of PU applied alone, the treatments of SCU2, SCU2+PU(2:1), SCU1+PU(2:1) and SCU1+PU(1:1) showed significant increase in the rice yield, N accumulation, uptake and use efficiency, dry matter accumulation, ratio of stem-sheath usable carbohydrate to spikelets per panicle, and root α-NA oxidation ability that maintained a high level with a small reduction tendency. The grain yield, N uptake and use efficiency as well as dry matter accumulation in clay soil were slightly higher than those in sandy soil, and the root α-NA oxidation ability at heading and 10 days after heading were lower in clay soil than in sandy soil, while no apparent difference was found at 20 or 30 days after heading.In conclusion, the application of sulfur-coated urea or its combination with normal urea may both meet the basic needs of rice growth. Combination of SCU1 and PU has better effect than either fertilizer applied solely, the treatment of SCU2 has the best outcome, which is followed by treatment of SCU2+PU(2:1), and treatment of SCU2+PU(1:1) does not show a significant effect.

Effects of No-Tillage with Rotation on Soil Water Retaining Properties and Crop Yield in Inner Mongolia

GUO Xiao-Xia, LIU Jing-Hui, TIAN Lu, ZHANG Xing-Jie, LI Li-Jun, and ZHANG Xiang-Qian

Acta Agron Sin. 2012, 38(08):  1504-1512.  doi:10.3724/SP.J.1006.2012.01504

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In 2005–2011, the effects of five tillage methods including no-tillage with high stubble mulching(NHS), no-tillage with low stubble mulching(NLS), no-tillage with high stubble(NH), no-tillage with low stubble(NL), and conventional tillage(T) combined with three rotation patterns(oat-soybean-corn, soybean-corn-oat, corn-oat-soybean) on waterretaining properties and crop yield were studied in Qing Shuihe county of Inner Mongolia. The results showed thatno-tillage combined with rotations increased the soil water retaining capacity, and there was a positive correlation between soil water storage and rainfall. Among different treatments, the two no-tillage with stubble mulching combined with oat-soybean-corn rotation had the biggest effect to increase the soil water storage that was 35.66–41.63% higher as compared with conventional tillage. All the no-tillage methods combined with rotation patterns were able to increase crop water use efficiency and crop yield that was positively correlated with rainfall. After the first rotation cycle, compared with conventional tillage, the soil water use efficiency of NHS, NLS, NH, and NL increased by 43.77%, 31.45%, 26.74%, and 13.91%, the crop yield increased by 29.68%, 27.69%, 18.05%, and 15.66%. In the second rotation cycle, the drought was serious, which resulted in the decreased effects of no-tillage combined with oat-soybean-corn rotation, but the crop water use efficiency of NHS, NLS, NH and NL increased by 29.83%, 20.51%, 6.18%, and 3.15%, the crop yield increased by 17.52%, 13.60%, 4.33%, and 1.95%, as compared with conventional tillage. So in the arid area of Inner Mongolia where the rainfall is the major source of soil water, no-tillage combined with rotation can improve the ability of storing moisture in soil, and increase crop yield, especially the no-tillage with stubble mulching combined with oat-soybean-corn rotation.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effect of Water Stress on Seedling Growth and Photosynthetic Characteristics in Broomcorn Millet

FENG Xiao-Min,ZHANG Yong-Qing

Acta Agron Sin. 2012, 38(08):  1513-1521.  doi:10.3724/SP.J.1006.2012.01513

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The response of main growth characters and photosynthetic parameters in seedlings of Broomcorn millets cultivars Longmi 4 (drought resistant), Jinshu 7 (drought-sensitive) and 5283 Huang (medium drought resistant) to three different drought stresses and normal irrigation were studied in a pot experiment. The result showed that drought stress decreased plant height, leaf area, root weight, chlorophyll content, and root activity. In addition the decreased range of Jinshu 7 was bigger than that of Longmi 4 and 5283 Huang. With the increasing of drought stress, fixation fluorescence value (F_o) and non photochemical quenching coefficient (q_N) increased significantly, in Longmi 4, 5283 Huang, and Jinshu 7, F_o increased by 24.6%, 34%, and 40.8%; q_N increased by 0.956, 1.083, and 2.183, however,F_v, F_m, F_v/F_m, F_v/F_{o, and qP}all decreased under water stress,with the significant differences compared with that from those in the control under moderate stress and serious stress. Water stress decreased photosynthetic rate, transpiration rate, stomatal conductance and CO₂ concentration, which were lower in Longmi 4 than in Jinshu 7 and 5283 Huang, indicating that higher photosynthetic efficiency, stronger light energy transfer capacity and greater relative growth rate in Longmi 4 may be the major physiological traits adapted to drought stress. Sensitivity of broomcorn millet leaves to light increased under water stress, making injury of drought and photo inhibition to photosystem II, the severer drought and the weaker drought resistance, therefore we should water the broomcorn millet seedlings to avoid the injury of severe drought and high light.

Effects of Continuous Cropping on Photosynthesis and Medicinal Quality of Pseudostellariae heterophylla

ZENG Ling-Jie,LIN Mao-Zi,LI Zhen-Fang,DAI Lin-Quan, LI Ji,LI Jing-Jing,ZHANG Zhong-Yi,LIN Wen-Xiong

Acta Agron Sin. 2012, 38(08):  1522-1528.  doi:10.3724/SP.J.1006.2012.01522

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Monocropping is one of cultivation systems for many crops in production, especially for Pseudostellariae heterophylla, one of Chinese herbal medicinal plants. Continuous cropping will cause a series of problem. In the paper, we designed a continuous cropping of Pseudostellariae heterophylla and rotaton of Pseudostellariae heterophylla and rice to explore effects on photosynthetic physiology and medicinal quality of P. heterophylla. The results showed that compared to the rotation, the yield of continuous cropping of P. heterophylla was significantly (P<0.01) declined, only corresponding to one third of the rotation’s, polysaccharide content and ginseng saponins Rb1 of the tuberous root reduced by 88.08% and 44.33%, respectively. The dynamic measurement of FluorCam fluorescence indicated that F_o was not declined significantly (P>0.05), and NPQ decreased significantly (P<0.05). The relative chlorophyll content of leaf (SPAD) (P<0.01) and P_n (P<0.05) declined. The decreased cell density in leaf and root was observed with microscope. In conclusion, the photosynthetic system was damaged by continuous cropping, especially for the protection mechanism. The light energy absorbed by PSII antenna pigment cannot be used in photosynthesis or dissipated, but accumulated in the leaves, which causes disordered photosynthesis, declined photosynthetic rate and malformed organs. The pathologic, and finally affects the morphogenesis of root that may be an important faction in restricting the yield and quality of P. Heterophylla.

REPORT

Characteristics of Plant Morphological Parameters and Its Correlation Analysis in Maize under Planting with Gradually Increased Density

TANG Li-Yuan,LI Cong-Feng,MA Wei,ZHAO Ming,LI Xiang-Ling,LI Lian-Lu

Acta Agron Sin. 2012, 38(08):  1529-1537.  doi:10.3724/SP.J.1006.2012.01529

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The object of this study was to analyze the dynamic characteristics of plant stalks morphological parameters and its effect using four maize cultivars (Zhengdan 958, Xianyu 335, Denghai 661, Yinong 103) with 13 treatments of gradually increased density from 1.67 to 16.67 plants m^-2 under planting with gradually increased density in field experiments. Final yield and physical plant height, stem diameter at jointing stage, huge bellbottom stage and physiological maturity stage were measured. The results showed that with density increase progressively, the plant height rose at jointing stage and then declined after huge bellbottom stage, the ear height and height ratio of ear to plant climbed up. Lodging easily occurred when height ratio of ear to plant was greater than 0.4. Therefore lodging rate could be decreased if the ear height lowered. Internodes had the trends of elongation below the ear and contraction above the ear, and shortened from top to bottom in the whole stem. The ratio of broadside to narrowside of stem diameter had no significant changes. Plant height, ear height and stem diameter all reflected to densities harmonically. Stem elongation was main displayed by internodes below the ear, ear height and height ratio of ear to plant had very significant negative correlation with stem in different stages, and the correlation coefficient of above –0.7701^**.

Generation of Aphid Resistant Transgenic Wheat with aha From Arisaema heterophyllum by Particle Bombardment

ZHANG Yan,YU Xiu-Dao,TANG Ke-Xuan,XIA Lan-Qin

Acta Agron Sin. 2012, 38(08):  1538-1543.  doi:10.3724/SP.J.1006.2012.01538

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Agglutinin is a class of mannose-binding protein, which has detrimental effect on aphids and other pests. In this study, the vector harboring aha cloned from Arisaema heterophyllum directed by rice Rubisco small subunit promoter (rbcS) was constructed. By co-transformed with pAHC20 that harbors bar selection gene, the aha gene was transferred into wheat variety Kenong 199 via bombardment. After induction, regeneration, two rounds of selection and with the conformation by PCR analysis, 42 transgenic plants with foreign aha gene were obtained, average co-transformation efficiency of 2.41%. According to PCR analysis, the segregation of the T₁plants was basically consistent with Mendel’s separation. Aphid resistance bioassay was carried out using eight randomly selected transgenic lines by multiple discrimination method. One high-resistant and three low-resistant transgenic lines were identified, accounting for 44.4% of the tested materials. This study has laid a basis for application of aha gene in development of aphid resistant transgenic wheat.

Effects of Agronomic Measures on Mechanical Transplanting Long-Age Seedlings of Super Rice in Rapeseed (Wheat)-Rice Planting Area of Chengdu Basin

LI Xu-Yi,CHI Zhong-Zhi,JIANG Xin-Lu,ZHENG Jia-Guo,Guo Xiang

Acta Agron Sin. 2012, 38(08):  1544-1550.  doi:10.3724/SP.J.1006.2012.01544

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The effects of agronomic measures including sowing norm, date and types of seedling tray on rice long-age seedlings, were studied by using super rice, II-you 602, in wheat (rapeseed)-rice planting area in Chengdu basin. The results indicated that in normal sowing time, though rooting ability of long-age seedlings decreased from 30 to 42 days after sowing, the population size of seedlings declined slowly, root-shoot ratio, width of stem base and dry weight per unit seedling height increased. However, between 42 and 54 days after sowing, the population size of seedlings decreased sharply, root-shoot ratio and dry weight per unit seedling height began to decline, and rooting ability of long-age seedlings continued to fall. With postponement of sowing time, the population size of seedlings increased, but root-shoot ratio, rooting ability and dry weight per unit seedling height not improved dramatically and even declined. Thesowing norm of 431.03 to 554.19 g m^-2 was beneficial to population size and individual quality. The effects of plastic cell-tray were better when seedling age over a certain phase (about 40 days after sowing), the descending of seedling quality and population size was slower, whether further seedling age was prolonged or sowing norm properly increased. The above results showed that sowing date of around April 15, sowing norm of 431.03 to 554.19 g m^-2, using hard plastic cell-tray and seedling age of about 42 days were good for raising mechanical transplanting long-age seedlings by the dry raising method of rice seedlings in Chengdu basin.