Table of Content

12 September 2011, Volume 37 Issue 09

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Genetic Stability of Rice Aneuploid during Its Asexual Propagation

GONG Zhi-Yun, SHI Guo-Xin, LIU Xiu-Xiu, YI Chuan-Deng, YU Heng-Xiu

Acta Agron Sin. 2011, 37(09):  1505-1510.  doi:10.3724/SP.J.1006.2011.01505

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Telotetrasome is a kind of aneuploid with two additional identical telocentric chromosomes. To investigate the genetic stability of riceaneuploid during its asexual propagation,a telotetrasome (2n+·8S+·8S) was selected from the progenies of a rice telotrisome (2n+·8S), and preserved by asexsual reproduction. But one of the extra short arms (·8S) was easy to be lost in the asexual propagation offspring of 2n+·8S+·8S and led to morphological variations. FISH results indicated that one of the two extra ·8S was short of detectable rice centromeric satellite repeat (CentO) and centromere-specific retrotransposon (CRR) and could not be transmitted stably. The other extra ·8S contained CRR, but not detectable CentO and could be transmitted steadily. However, the extra ·8S contained the CentO and CRR sequences simultaneously in the initial telotrisomic line (2n+·8S). These results showed that CentO and CRR of the extra ·8S may be randomly lost and led inheritance instability in the aneuploid harbouring extra ·8S during asexual propagation.

QTL Mapping for Yield Related Traits Using Two Associated RIL Populations of Wheat

DING An-Ming, LI Jun, CUI Fa, ZHAO Chun-Hua, MA Hang-Yun, WANG Hong-Gang

Acta Agron Sin. 2011, 37(09):  1511-1524.  doi:10.3724/SP.J.1006.2011.01511

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Using inclusive composite interval mapping (ICIM) method, we detected QTLs responsible for spikelet number per spike (SN), grain number per spike (GN), spike number per plant (PN), 1000-grain weight (GW), and grain yield per plant (GY) in associated RIL populations WY (229 lines) and WJ (485 lines), which were planted in four growing environments. Numerous QTLs for the five yield-related traits were located on 21 chromosomes of wheat. In the WY population, nine, nine, four, seven, and five QTLs were detected for SN, GN, PN, GW, and GY, respectively. Among these QTLs, 16 explained more than 10% of the phenotypic variations. In the WJ population, the numbers of QTLs for the above five traits were 20, 16, 11, 14, and 9, respectively, of which only three QTLs had phenotypic contribution higher than 10%. In addition, five QTLs were identified in two environments in the WY population and 17 QTLs were identified in at least two environments in the WJ population. Pleiotropy phenomenon or chromosome regions with closely linked QTLs were observed in both populations. Nine pairs of QTLs and two chromosome regions were inferred to be identical between the two populations because these QTLs and chromosome regions shared the same flanking markers. These results may enrich the QTL information for yield components of wheat and facilitate marker assisted selection.

QTL Analysis for Plant Height and Heading Date in Rice under Two Nitrogen Levels

FENG Yue, ZAI Rong-Rong, CAO Li-Yong, LIN Ze-Chuan, WEI Xin-Hua, CHENG Shi-Hua

Acta Agron Sin. 2011, 37(09):  1525-1532.  doi:10.3724/SP.J.1006.2011.01525

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A recombinant inbred line (RIL), derived from a super hybrid rice cross of XQZB/R9308 and its genetic linkage map were used to identify QTLs through Windows QTL Cartographer 2.5 for plant height (PH) and heading date (HD) under low and normal nitrogen conditions in rice. Nine QTLs for PH and eight QTLs for HD were detected under two nitrogen levels, four QTLs for trait differences of PH and HD were detected between the two environments, explaining 5.68–18.40% of phenotypic variation. The pleiotropic QTLs influencing PH and HD were detected near RM5436 on chromosome 7 and in the interval RM5556–RM310 on chromosome 8, which showed high contribution of genetic effects and the position alleles were all originated from R9308. These QTLs are favorable for marker-assisted selection. One QTL for HD difference and one QTL for PH difference were detected in the interval RM5916–RM166 on chromosome 2 and in the interval RM2366–RM5767 on chromosome 8, which were considered to directly contribute to nitrogen use efficiency in rice.

Construction and Application of a Reference Plasmid Suitable for Determination of CpTI and cry1A Gene Dosages in Genetically Modified Cottons

SU Chang-Qing, XIE Jia-Jian, SUN Xiao, PENG Yu-Fa

Acta Agron Sin. 2011, 37(09):  1533-1539.  doi:10.3724/SP.J.1006.2011.01533

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In transgenic detection field, a preferable reference material (RM) has been developing with the advantage of easy availability, high purity, low cost and good stability, which is more suitable for detecting multiple target genes. In the present study, we constructed a multi-target reference plasmid named pMD-CCS containing cowpea trypsin inhibitor (CpTI) and Bacillus thuringiensis insecticidal crystal protein (cry1A) and cotton endogenous gene Stearoyl-acyl carrier protein desaturase (Sad1) sequencestargeting the key exogenous gene types of the insect resistant cotton varieties (Gossypium hirsutum L.) in China. The real-time quantitative PCR methods for CpTI and cry1A were established using pMD-CCS as the RM.Thedosagess of CpTI and cry1A from nine insect resistant cotton varieties were determined. The average CpTI dosages were 0.020–0.018 copies/genome and the average cry1A dosages were 1.377–2.136 copies/genome in three insect resistant cotton varieties including Kemian3. The average cry1A dosages were 0.887–2.564 copies/genome in six ones including Ezamian1-F₁. The standard deviations (SD) of the quantitative measurement ranged from 0.001–0.049. The above results demonstrated that pMD-CCS could be used as the RM for the quantitative measurement of CpTI and cry1A genes in insect resistant cotton varieties.

Identification and Analysis of Differentially Expressed Proteins of BNS Male Sterile Line and Its Conversion Line of Wheat

LI You-Yong, RU Zhen-Gang, SU Qing, FU Qing-Yun

Acta Agron Sin. 2011, 37(09):  1540-1550.  doi:10.3724/SP.J.1006.2011.01540

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BNS is a new type of thermo-sensitive nuclear male-sterile lines in wheat (Triticum aestivum L.). The mechanism of itssterility was studied using two-dimensional electrophoresis and MALDI-TOF-MS methods. Anthers of the sterile line (SL) and the conversion line (CL, fertile pollen rate higher than 50%) were obtained from plants with a series seeding dates, and two set of samples were used to compare the differentially expressed proteins which was extracted from the anthers at early stage of uninucleate and from late stage of uninucleate to binucleate stage of pollen development. The abundant expressions of proteins involved in respiratory and photosynthetic energy metabolism were identified in the CL, such as ATP synthase α and β subunit, NAD (P) Rossmann fold binding protein, cytoplasmic malate dehydrogenase, mitochondrial aldehyde dehydrogenase subunit, and Rubisco subunit protein. However, they were absent or down-regulated in the SL. Besides, a few abnormal proteins were detected in the SL, including sorbitol dehydrogenase, maturase K, histone H2B.2, Harpin-induced 1, and elongation factor TU. According to the functions of these differentially expressed proteins, we inferred that ATP synthase α and β subunits were most likely the source protein for the sterility of BNS. Their expressions are regulated by a temperature sensor that is located at upstream of the subunit gene operon in BNS. Mutation of the temperature sensor is determined by the temperature higher than a threshold, which may startup the transcriptions of α and β subunit genes. When the temperature is lower than the threshold, the expressions of α and β subunits are in very low levels, which affect the assembly of ATP synthase, and result in deficiency of ATP supply for the growth of microspore. This effect can be amplified in downstream physiological functions, such as development of respiratory and photosynthetic enzymes, which finally causes abnormal metabolism and pollen sterility.

Cloning and Salt-tolerance Analysis of Gene Plastid Transcriptionally Active (GhPTAC) from Gossypium hirsutum L.

ZHOU Kai, YE Wu-Wei, WANG Ju-Juan, WANG De-Long, FAN Bao-Xiang, WANG Shuai

Acta Agron Sin. 2011, 37(09):  1551-1558.  doi:10.3724/SP.J.1006.2011.01551

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To develop novel salt-tolerance genes and adjustment pathway, we screened out gene Plastid Transcriptionally Active named as GhPTAC based on salt-tolerance gene chips and salt resistance related SSH library.The result of RACE and RT-PCR showed that the cDNA full length was 1 564 bp, and ORF was 1 038 bp, which encoded 345 amino acid residues. Bioinformatics analysis showed that GhPTAC shared the identity of 60.6% with the homologous gene PTAC13 from Arabidopsis thaliana. As one part of Transcriptionally active chromosome (TAC), GhPTAC plays a part role in regulation of transcription termination/ antitermination of chloroplastid genome. The GhPTAC expression was up-regulated under salt stress induction and the expression level of GhPTAC of Zhong 9806 (salt-resistant material) was obviously higher than that Zhong S9612 (salt-sensitive material) which was measured by Real-time PCR and in accord with the arrays results.

Development of Introgression Lines and Identification of QTLs for Resistance to Sheath Blight

GAO Xiao-Qing, XIE Xue-Wen, XU Mei-Rong, WANG Lei, SHI Ying-Yao, GAO Yong-Meng, ZHU Lian-Hua, ZHOU Yong-Li, LI Zhi-Kang

Acta Agron Sin. 2011, 37(09):  1559-1568.  doi:10.3724/SP.J.1006.2011.01559

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In this study, two random BC₂F₂ populations were developed by cross and backcross, in which two major hybrid restorer lines Shuhui 527 and Minghui 86 were used as recurrent parents respectively, and Jiangxisimiao used as donor. The bulks of the BC₂F₂ populations were inoculated with Rhizoctonia solani to screen the lines resistant to sheath blight, and 49 resistant introgression lines (ILs) were selected. The genotypes of ILs were analyzed with evenly distributed polymorphic SSR markers, and a total of 12 significant loci were identified by χ² test analysis. Among them, two allelic frequency-deviation loci were located in the same or near regions identified in the previous studies. In the field test without artificial inoculation, there was no significant difference between all the agronomic traits investigated in the selected ILs and their recurrent parents. Under heavily diseased conditions, six ILs with Shuhui 527 background and two ILs with Minghui 86 background showed similar agronomic traits and significantly higher resistance to sheath blight than their recurrent parents at two experimental sites, which can be served as immediate sources of sheath blight resistance for hybrid rice breeding and directly used in hybrid rice production.

Comparative Genomics Analysis and Constructing EST Markers Linkage Map of Powdery Mildew Resistance Gene pm42 in Wheat

LIU Zi-Ji, ZHU Jie, HUA Wei, YANG Zuo-Min, SUN Ji-Shen, LIU Zhi-Yong

Acta Agron Sin. 2011, 37(09):  1569-1576.  doi:10.3724/SP.J.1006.2011.01569

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Constructing fine genetic linkage map of target gene provides a starting point for map-based cloning. Fine genetic mapping of functional genes in wheat has benefited greatly from comparative genomics analysis. The genome sequences of rice and Brachypodium distachyon provide powerful tools for comparative genomics analysis and fine genetic mapping of target gene in wheat. In the present study, comparative genomics analysis using wheat-Brachypodium-rice genomic colinearity showed that genomic region containing pm42 in wheat 2BS was orthologous to Brachypodium chromosome 1 and rice chromosome 3. Two EST-SSCP markers, CD452782 and BF201235, three EST-STS markers, CJ674042,EB513371, and CV771633, linked to pm42 were developed and an EST marker-based genetic linkage map of pm42 was constructed. CJ674042, BF201235, CD452782, and CV771633 were distal to pm42 with genetic distances of 1.9, 12.0, 19.7, and 25.7 cM, respectively. EB513371 was proximal to pm42 with a genetic distance of 14.6 cM. An integrated high-density comparative genomics genetic linkage map of pm42 was constructed and the powdery mildew resistance gene was mapped in a 3.3 cM interval orthologous to 66 kb and 69 kb genomic regions in Brachypodium chromosome 1 and rice chromosome 3, respectively, providing useful information for the fine mapping, molecular assisted selection and gene pyramiding of pm42.

QTL Analysis of Six Important Traits in Tobacco (Nicotiana tabacum L.)

LI Hua-Li, CHEN Mei-Xia, ZHOU Dong-Xin, CHEN Shun-Hui, TAO Ai-Fen, LI Yan-Kun, MA Gong-Bo, QI Jian-Min, GUO Yu-Chun

Acta Agron Sin. 2011, 37(09):  1577-1584.  doi:10.3724/SP.J.1006.2011.01577

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The agronomic traits, chemical components and diseases are very important factors affecting the yield and leaf quality of tobacco. QTLs linked to the three aspects of traits can be used in marker-assisted selection for the yield and leaf quality improvement in tobacco. The objective of this study was to identify QTLs controlling important traits in tobacco, which could promote the basic research of molecular marker-assisted selection breeding. A population with 127 F₂ and F_2:3 individuals from the cross between Taiyan 7 and Baile 21 was used to establish a genetic linkage map of tobacco, 190 marker loci were mapped into 26 linkage groups which spanned a total map length of 3 483 cM. With a randomized complete block design, two location field tests with three replicates one year were conducted to charactererize six important traits, including nicotine, total chlorine, total kalium, leaf length, leaf angle, and powdery mildew. Utilizing data of field trials and MCIM method, QTLs for six important characters were mapped and their genetic interactions were analyzed. As the results, two QTLs for nicotine, two QTLs for total chlorine, one QTL for total kalium, four QTLs for leaf length, one QTL for leaf angle, and one QTL for powdery mildew were detected, of which six QTLs had additive effect, and the others were epistatic. The results indicated that epistatic QTLs, the additive QTLs also played important roles in the genetic basis of the six important traits with eleven gene loci in tobacco.

Inheritance Analysis of Lysine Content in Maize Kernel and Its Relationship with Grain Yield

TANG Ji-Hua, JI Hong-Jiang, LIU Xi-Bao, ZHANG Jun, TAN Xiao-Jun, HU Pan-Min, LIU Zong-Hua

Acta Agron Sin. 2011, 37(09):  1585-1591.  doi:10.3724/SP.J.1006.2011.01585

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Fifteen inbred lines selected from five basic populations in maize (Zea mays L.) were crossed with five elite inbred lines derived from different heterotic groups according to NCII design, and the 75 combinations were evaluated at two environments in 2009. The lysine content in kernels of parents as well as their hybrids F₁ and F₂ populations was analyzed using the Near Infrared Reflectance Spectroscopy (NIRS) method. Statistical analysis of lysine contents was made based on the model of triploid seed endosperm, cytoplasm and maternal effect. The results showed that lysine content in kernels was controlled not only by three sets of genetic system, namely seeds, maternal effects and cytoplasm effects, but also affected by environmental factors. The genetic variance of V_G (V_G=V_A+V_D+V_C+V_Am+V_Dm) accounted for 76.3% of total genetic variance (V_G+V_GE), of the total genetic variance V_G , variances of seed effect (V_A+V_D), cytoplasm effect (V_C) and maternal effect (V_Am+V_Dm) accounted for 24.6%, 19.7%, and 55.7%, respectively. The maternal heritability (h²_m=40.98%) of lysine content was the highest, followed by seed heritability (h²_o=17.86%), whilethe cytoplasm heritability (h²_c=14.29%) was relatively lower. No significant correlation was found between the lysine contents in kernel and grain yield (r = –0.0269). Therefore,much attention should been paidto selecting high-value parental lines, especially female lines, in lysine content and to making diversified crosses among lines from different maize heterotic groups in high-lysine breeding. Based on the results from this study, it seems to be possible to improve lysine content and grain yield simultaneously from materials with extensive variances.

Development of Microsatellite Markers for Astragalus sinicus L. and Its Application for Variety Identification

CHEN Jian, ZHANG Hui, ZHU Bing-Yao, LIN Xin-Jian

Acta Agron Sin. 2011, 37(09):  1592-1596.  doi:10.3724/SP.J.1006.2011.01592

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Astragalus sinicus L. is a traditional green manure used in rice field in China. To identify Astragalus sinicus L varieties in agricultural production, we developed SSR molecular markers by using biotinylated (AG)_15,(CT)₁₅, (AC)₁₅, (GT)₁₅ probes and streptavidin coated magnetic beads, the SSR sequences were enriched from A. sinicus genome. Of the 950 transformantsselected from the library constructed by obtained fragments, 127 clones were confirmed as SSR insert by PCR identification and final sequencing, with a SSR enrichment efficiency of 15.8%. By deleting the duplicated and unavailable sequences, 33 SSR loci were used for primer design. After nine A. sinicus varieties were sampled for analysis of the genetic diversity based on these SSR primers, only six SSR primer pairs amplified a total of 18 stable and repeatable polymorphic bands within tested plant samples. At the level of variety population of A. sinicus, based on these SSR loci we calculated the percentage of polymorphic band ranging from 50% to 100%, effective number of alleles ranging from 1.19 to 1.64, Nei’s gene diversity ranging from 0.13 to 0.38, and Shannon’s information index ranging from 0.22 to 0.56; the selected six primer pairs could completely distinguish the tested plant samples, and the application of these SSR loci for fingerprinting identification of variety was proved to be feasible to A. sinicus. Based on similar coefficient generated from six SSR loci, we clustered nine tested varieties of A. sinicus mainly into two groups, which had no certain linkage to the traditional classification of variety according to its growth period. The studyopened up a prospect of using SSR molecular marker for genetic analysis, variety identification, and protection of intelligent property in commercial breeding of A. sinicus.

Seed DNA Methylation in Response to Heat Stress in Brassica rapa L.

GAO Gui-Zhen, YING Fei, CHEN Bi-Yun, LI Hao, LV Xiao-Dan, YAN Gui-Xin, XU Kun, WU Xiao-Meng

Acta Agron Sin. 2011, 37(09):  1597-1604.  doi:10.3724/SP.J.1006.2011.01597

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High temperature or heat stress, causes thermal damage to plants, and affects plant growth, development, as well as seed longevity. By using a seed heat tolerant genotype qingyuanbendiyoucai and a seed heat susceptive genotype shaoxingaidaganyoucai, This study aimed at investigation of the effect of different temperature treaments on seed vigor and DNA methylation of these two landraces of Brassica rapa L. The result showed that the seed germination percentage and the vigor index present no significant difference from those of CK under 37°C and 4°C, the seed vigor declined significantly under 70°C of heat stress, and heat acclimation in 37°C for 2 h effectively enhanced seed thermo-tolerance. The results of MSAP analysis showed that the level of global DNA methylation decreased under 70°C of heat stress, both DNA methylation and demethylation were detected, and more DNA demethylation bands were recorded. Seed germinating potential, germination percentage, hypocotyl length, vigor index were significantly negatively correlatied with number of bands of full-methylated (both bands) at the internal cytosine, but positively correlated with the the number of bands of full-methylated (both bands) at the external cytosine. Most importantly, opposite patterns of DNA methylation were discovered in heat tolerant and susceptive seeds under 70°C heat stress, more bands of DNA demethylation were detected in the heat tolerant seeds, but more bands of DNA methylation were detected in the heat susceptive seeds, which suggested that DNA methylation and demethylation play an important role in seed heat tolerance, epigenetic regulation of gene expression by DNA methylation is important for plant to cope with heat stress.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Mechanism of Maize Kernel Setting and Characteristics of Kernel Growth and Development Studied by Controlling Pollination

FENG Han-Yu, WANG Zhi-Min, KONG Fan-Na, ZHANG Min-Ji, ZHOU Shun-Li

Acta Agron Sin. 2011, 37(09):  1605-1615.  doi:10.3724/SP.J.1006.2011.01605

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In order to clarify the characteristics of kernel growth and development within different maize ear regions and their relationships, the changes of kernel weight and kernel volume of fertilized ovaries, and their relationships with kernel setting rate of three maize cultivars were studied by three types of controlling pollination, including no-pollination within middle or basal region of ear (type I), no-pollination of whole row filaments of ear (type II) and preferred pollination of apical-middle filaments of ear (type III). The results showed that the weight and volume of apical kernel were improved and developed normally, but the ear kernel number and ear kernel weight decreased by applying the controlling pollination. For the apical kernel of type I, there were no significant differences in weight and volume compared with the middle or basal kernel of the treatment of complete pollination at the same time and the treatment of natural pollination, but the weight and volume of the apical kernel was the smallest in a maize ear. The kernel setting rate was improved in type II and type III. Correlation analysis showed that grain dry weight and volume were significantly positively correlated with kernel setting rate at P<0.01 in type II but significantly negatively at P<0.05 in type III. These data indicate that the apical kernel of maize ear can develop normally and its kernel weight also can be regulated, the shortage of nutrient supply may be the fundamental reason of the abortion and lower weight of apical kernels, and it is an effective practice to improve ear kernel weight by enlarging the source and sink.

Relationship between Lignin Metabolism and Lodging Resistance in Wheat

CHEN Xiao-Guang, SHI Chun-Tu, YIN Yan-Ping, WANG Zhen-Lin, SHI Yu-Hua, PENG Dian-Liang, NI Yang-Li, CAI Tie

Acta Agron Sin. 2011, 37(09):  1616-1622.  doi:10.3724/SP.J.1006.2011.01616

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As a component of cell wall, lignin is believed to be relevant to mechanical intensity of culm. In this study, we investigated the dynamic changes of lignin content and activities of four enzymes involved in lignin metabolism in culm as well as the snapping resistance and lodging index of wheat (Tritcum aestivum L.) to disclose the relationship between lignin content and lodging resistance. The lignin content and activities of phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), cinnamyl alcohol dehydrogenase (CAD), and 4-coumarate: CoA ligase (4CL) were tested with the second internode of six cultivars with different lodging resistance. The snapping resistance and culm lodging index were determined at anthesis, milking, and maturity stages. The lignin content varied significantly among cultivars. Jimai 22 and Jimai 20, which showed high resistance to culm snapping and loging, had higher lignin content and the activities of PAL, TAL, CAD, and 4CL than other cultivars. The lignin content was negatively correlated with the actual lodging ratio (r = -0.83, P < 0.05), and positively correlated with the snapping resistance of culm (r = 0.86, P < 0.05). The activities of PAL, TAL, and CAD were positively correlated with lignin content with correlation coefficients of 0.78 (P < 0.05), 0.77 (P < 0.05) and 0.85 (P < 0.05), respectively. Based on these results, we conclude that high activities of PAL and CAD are the enzymatic basis of increased lignin content, and the lignin content in culm can be used as an important indicator to evaluate lodging resistance of wheat.

Water Use Characteristics of Alternately Irrigated Wheat/Maize Intercropping in Oasis Region of Northwestern China

CHAI Jiang, YANG Cai-Gong, HUANG Gao-Bao

Acta Agron Sin. 2011, 37(09):  1623-1630.  doi:10.3724/SP.J.1006.2011.01623

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In oasis irrigation region of northwestern China, the decreasing of multiple cropping areas may lead to significant reduction of land and light use efficiencies due to serious water shortage. Therefore, water-saving irrigation is a priority in the research on theory and technology for intercropping system. Alternate irrigation is a technique to save water and enhance water use efficiency (WUE) simultaneously in common cropping systems. However, its effect is not clear on intercropping system. In 2006–2008 cropping years, we carried out a field experiment in oasis region of Hexi Corridor, Gansu Province, China under wheat/maize intercropping to disclose the effects of alternate irrigation on crop yields, water consumption, and WUE. The results showed that, compared to sole cropping treatments, there was a significant increase of land equivalent ratio (LER) in the alternately irrigated wheat/maize intercropping treatment with the LER values ranging from 1.22 to 1.52 under different irrigation levels of the intercropping treatments. However, the difference of LERs between conventionally irrigated and alternately irrigated intercropping systems was not significant at the same irrigation quota. Compared to the conventionally irrigated intercropping treatment, there was no significant change of wheat yield in the alternately irrigated intercropping treatment, but significant increase by 11.4–36.4% in maize yield. Therefore, the total yield of wheat and maize in the alternately irrigated intercropping treatment was increased by 12.9 averagely. The water consumption in the alternately irrigated intercropping treatment had no significant increase compared to that of the conventionally irrigated intercropping treatment, with 1.2–19.4% higher than the weighted average of monoculture of both crops. The WUE of alternatiely irrigated intercropping treatment was 0.9–22.5% higher than that of the conventionally irrigated intercropping treatment, and 12.0–71.4% and 10.6–37.8% higher than that of wheat and maize monoculture, respectively. These results suggest that alternate irrigation is feasible in intercropping systems in arid oasis regions with the purpose of saving water and increasing WUE.

Influence of Planting Methods on Grain-Filling Properties of Super Rice

LI Jie, ZHANG Hong-Cheng, GONG Jin-Long, CHANG Yong, DAI Ji-Gen, HE Zhong-Xiang, HU Ke, WEI Hai-Yan, GAO Hui

Acta Agron Sin. 2011, 37(09):  1631-1641.  doi:10.3724/SP.J.1006.2011.01631

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To explore grain-filling properties of high-yielding rice under different planting methods, we studied the grain-filling processes of superior and inferior grains of two super rice cultivars (Huaidao 9 and III you 98) with Richards equation W=A/(1+Be^–Kt)^1/N and three planting methods, i.e. precisionartificial transplanting with dry nursery middle and strong seedlings (ATR), mechanical transplanting with small seedlings (MTR) and direct seeding (DSR). The results were as follows. (1) The super rice yields under different planting methods were significantly different, ATR was the highest, followed by the MTR, and the lowest was the DSR. Compared with ATR and MTR, the 1000-grain weight and seed-setting rate of DSR were significantly lower, but the changes between ATR and MTR were different due to different types of cultivar. (2) The grain-filling processes of superior and inferior grains of super rice under different planting methods were obviously asynchronous type. The time reaching the maximum grain-filling rate (T_max) of superior grains was early, maximum grain-filling rate (GR_max), mean grain-filling rate (GR_mean), the final weight of a kernel (A) and initial grain-filling potential (R₀) were significantly greater than those of inferior grains. However, the active grain-filling period (D) and effective grain-filling time (T₉₉) of the superior grains were significantly less than those of inferior grains. (3) Compared with ATR and MTR, the GR_max and GR_mean of superior grains of DSR were significantly lower, T_max was obviously delayed, D and T₉₉ significantly increased. The GR_max and GR_mean of inferior grains of MTR were the highest, and ATR was slightly lower than DSR. For T_max, DSR was the earliest, MTR was the second, and the latest was ATR. D and T₉₉ reduced in order for ATR, MTR and DSR. (4) For grain-filling characteristics of different stages, the maximum of mean grain-filling rate and contribution rate was present at the middle stage, and the contribution rates of superior and inferior grains were up to 60.53% and 50.78%, respectively. The grain-filling days, mean grain-filling rate and contribution rate of the early, middle and late stages among different planting methods were different due to grain positions. (5) 1000-grain weight was positively correlated with maximum grain-filling rate, mean grain-filling rate and active grain-filling period of superior and inferior grains, and the correlations with maximum grain-filling rate and mean grain-filling rate of inferior grains were significant. Seed-setting rate had in a degree of positive or negative correlations with the grain-filling parameters of the superior and inferior grains, however, except the active grain-filling period of superior grains, all of the correlations were not significant. The results suggested that planting methods have significant influence on grain-filling properties of super rice. Although the grain-filling processes are all asynchronous types, the grain-filling parameters such as maximum grain-filling rate and the time reaching the maximum grain-filling rate of superior and inferior grains have great difference among different planting methods. It would play an important role in improving 1000-grain weight and grain-filling rate, especially the grain-filling rate of inferior grains under the conditions maintaining the final weight of a kernel and seed-setting rate stable.

Chilling Disaster Factors in Maize Reproductive Stage Based on Crop Growth Model

MA Yu-BIng, WANG Dan-Li, LI Wei-Jing

Acta Agron Sin. 2011, 37(09):  1642-1649.  doi:10.3724/SP.J.1006.2011.01642

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In recent years, temperature in the Northeast of China has been significantly increasing with global warming. However, since planting areas of relatively late-maturing varieties of maize are shifting towards north, the frequency and intensity of maize chilling disaster are increased in some areas and some years. The prevention and mitigation of chilling disaster of maize in the Northeast depend on our understanding about chilling disaster factors and the degrees of impacts. In this paper, using North East China Maize Growth Model (NEC_MaGM) and historical chilling disaster data, we analyzed temporal and spatial variations of low temperature during the grain filling period and the first frost day, and discussed the match relations between chilling years based on the two disaster factors and actual chilling years. The results indicated that NEC_MaGM had a satisfied outcome in simulating maize growth and development. The absolute deviation at simulated tasseling and maturity stages calculated by NEC_MaGM was 3.6 d and 5.9 d, respectively. The root mean square error of simulated weight of storage organ (WSO) was 839.5 kg ha^-1. The average temperature in grain filling stage of maize in the Northeast was 16.7–23.5°C. However, the rapid decrease of temperature (<16°C) that usually occurred in the late period of maize development stage had a great impact on grain filling. The average temperature on the first frost day in the Northeast was 7.4–9.2°C, which was below the threshold for maize growth. In addition, the first frost day in the Northeast had a trend of delay with time. However, maturity of new maize variety also delayed with global warming, so the first frost frequently occurred before maturity. When the average daily temperature of five successive days lower than 16°C occurred before DVS =1.9 (development stage), there was a severe impact on weight of storage organ (WSO). The years with above situation were consistent with those actually occurred in historical record. The partial early first frost occurred mainly in the period of 1.8<DVS≤1.9 in the Northeast. The numbers of sites where WSO reduced owing to the first frost were more than 11% in the Northeast for 44% of years. The years that the first frost occurred before maize maturity resulted in halt of WSO accumulation were consistent with historical record. It is concluded that low temperature in the grain filling period and the earlier first frost are the key factors of maize chilling disaster in the Northeast, which could be used as the indicators in earlier warning and prediction of chilling disaster based on the crop growth model output. Meanwhile, the crop growth model can be a powerful tool to analyze agro-meteorological disasters factors.

Effects of Nitrogen Application Strategy and Cultivation Model on the Performances of Canopy Apparent Photosynthesis of Indica Hybrid Rice Eryou 498 during Filling Stage

LI Xu-Yi, SUN Yong-Jian, CHENG Hong-Biao, ZHENG Hong-Zheng, YANG Zhi-Yuan, GU Xian-Wen, LIU Shu-Jin, HU Rong, MA Jun

Acta Agron Sin. 2011, 37(09):  1650-1659.  doi:10.3724/SP.J.1006.2011.01650

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A field experiment was conducted at Wenjiang and Hanyuan using indica hybrid rice Eryou 498. With the cultivation models including wide-narrow row spacing cultivation, triangle cultivation, spreading planting by expanding row spacing and reducing plant space, scattered planting cultivation. The results indicated that with the increase of N application at booting stage, canopy light transmittance performance improved, population quality index including single stem and sheath weight in heading, the ratio of leaf area of productive tillers and ratio of leaf area from flag leaf to 3rd leaf from top of productive tillers increased, leaf area index (LAI) and ratio of canopy respiration to total canopy apparent photosynthesis (CR/TCAP) decreased slightly, canopy apparent photosynthesis (CAP) increased first and decreased afterwards at Wenjiang, but showed decreasing trend at Hanyuan. When nitrogen fertilizer was applied at 60% before transplanting, 30% at tillering, and 10% at booting, it was beneficial to improving canopy light transmittance performance and population quality for wide-narrow row spacing cultivation and triangle cultivation, their CAP increased on the premise of no increasing in CR/TCAP, their ability of photosynthetic production improved at last. When nitrogen fertilizer was applied at 50% before transplanting, 30% at tillering, and 20% at booting, the increasing range of canopy light transmittance performance and population quality for spreading planting by expanding row spacing and reducing plant space was greater than that of other cultivation models, its CAP was higher than that of other cultivation models, but CR/TCAP did not increase at the same time, even decreased somewhat, so its capacity of photosynthetic production was higher than that of other cultivation models. When nitrogen fertilizer was applied at 40% before transplanting, 10% at tillering, and 50% at booting, scattered planting cultivation was propitious to improving population quality and interception of light, it had obvious advantages in photosynthetic production by increasing CAP during middle-late period of filling stage and decreasing CR/TCAP, but there was no advantage in photosynthetic production if temperature and light conditions was improved. From above, it was suggested that improving capacity of photosynthetic production should adopt suitable nitrogen application strategy according to ecological condition and cultivation model.

Adaptability of Varieties to Double Cropping in Early Spring and Late Summer

LI Li-Juan, WANG Mei-Yun, ZHAO Meng

Acta Agron Sin. 2011, 37(09):  1660-1665.  doi:10.3724/SP.J.1006.2011.01660

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Double-cropping is a new maize planting model in recent years. To explored the adaptability of varieties to the season and screen varieties suitable for double-cropping, we conducted trials in Laizhou, Shandong province, Jiaozuo and Xinxiang, Henan province in 2008–2010. The results showed that the accumulated temperature in early spring and late summer in different areas and years had the different impacts on each growth processes of species. The most varieties grown in early spring had higher yield than those in late summer, and most of the varieties seeded in the two seasons had the medium level of output(5 737–8 639 kg ha^-1). In variety selection, growing period was a important index, but grain number per spike was not. Yinong 103 had high and stable yields in the early spring, and Zhengdan 958 could ensure stable production at the second growing season in the late summer. Meanwhile,the adaptability of one variety to the environment in early spring and late summer also can reflect the comprehensive performance of the variety in agronomy.

Effects of Straw Recycling of Winter Covering Crop on Methane and Nitrous Oxide Emissions in Paddy Field

TANG Hai-Meng, XIAO Xiao-Beng, SHANG Wen-Guang, YANG Guang-Li

Acta Agron Sin. 2011, 37(09):  1666-1675.  doi:10.3724/SP.J.1006.2011.01666

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To learn the characteristics of CH₄ and N₂O emissions from paddy fields with different double rice cropping patterns will significantly benefit the exploitation of winter fallow paddy with covering crops and the assessment of rice cropping patterns. Therefore, the static chamber-GC technique with manual method was used to determine the effects of double rice cropping systems with different winter covering crops on the emissions of CH₄ and N₂O. These systems included ryegrass with no-tillage and double rice cropping (T₁), Chinese milk vetch with no-tillage and double rice cropping (T₂), rape seed with tillage and double rice cropping (T₃), potato with straw mulching and tillage and double rice cropping (T₄) and fallow and double rice cropping (CK). The results showed that straw recycling of winter crops significantly increased the emissions of CH₄ both during the early and later rice growing seasons than the CK. The T₄ and T₁ treatments had the largest CH₄ emissions during the early rice growing season with 20.713 and 16.068 g m^-2, respectively, while the T₄ and T₃ treatments had the largest CH₄ emission during the later rice growing season with 60.421 and 48.666 g m^-2, respectively. The four treatments with winter covering crops also had larger N₂O emissions both during the early and later rice growing seasons than the CK. N₂O emissions during the early rice growing season under T₁, T₂, T₃, and T₄ treatments were increased by 265.00%, 320.00%, 275.00%, and 65.00%, and during the later rice growing season by 157.89%, 113.16%, 134.21%, and 42.11%, respectively, compared with the CK. Meanwhile, the global warming potentials (GWPs) from paddy fields with different cropping patterns were T₄>T₃>T₁>T₂>CK. As a result, straw recycling of winter covering crops will significantly increase the emissions of CH₄ and N₂O from paddy field under double rice cropping systems.

Quantitative Determination of Peanut Seed Lipase Activity and Its Correlation with Storage Characteristics

GAO Ai, ZHANG Ying, LIU Ze, ZHANG Zheng-Zhu, TUN Ti-Jin, YU Shan-Lin, ZHANG Chen, TENG Bin, TUN Jing-De, JIANG Lan

Acta Agron Sin. 2011, 37(09):  1676-1682.  doi:10.3724/SP.J.1006.2011.01676

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Based on colorimetric determination method reported for rice lipase, we established a new method improving and optimizing the measurement for peanut seed lipase activity, with the optimum sampling amount of 5 mg and substrate concentration of 30 mg mL^–1. The method was validated to be accurate, specific and well repeatable. The lipase activities of 216 peanut germplasm resources were detected, with significant difference (P<0.001) among them. Five with higher lipase activity and five with lower lipase activity were screened, and each two of which were selected to perform an accelerated-aging experiment under high temperature and high moisture. The results indicated that, with extension of storage time, the germination rate of peanut with lower lipase activity decreased slowly, while that of peanut with higher lipase decreased rapidly, showing a negative correlation betweenseed vigor and peanut lipase activity (correlation coefficient was –0.8875). The study provides a reference for the further research in the effect of lipase on peanut storage characteristics.

RESEARCH NOTES

Identification of Yd2 Genotype in Barley with Molecular Markers and Their Application in Molecular Marker-assisted Selection

ZHAO Pan-Hong, WANG Yan-Fang, LI Run-Zhi, NIU Hong-Bin, XUE Jing-Ai, LIU Lin-De

Acta Agron Sin. 2011, 37(09):  1683-1688.  doi:10.3724/SP.J.1006.2011.01683

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The objectives of this study were to assess the feasibility of molecular markers YLM, CAPS-Ylp, and ASPCR-Ylp used in Yd2 gene identification in barley and to provide a rapid and effective marker-assisted selection (MAS) method for facilitating the application of Yd2 gene in resistance breeding to barley yellow dwarf virus (BYDV) in barley. The three markers were used to detect the Yd2 genotypes in fifty-two barley cultivars (lines) and four hybrids of F₁ generation. The resistance identification was performed to confirm the Yd2 genotypes of these cultivars (lines). Moreover, the three markers were applied to select the plants with Yd2 gene in a practice resistant-breeding program. The three markers could identify successfully the Yd2 genotypes of twenty barley lines and four F₁ hybrids with known Yd2 genotypes. This result confirmed that the effectiveness of the three markers in identification of Yd2 genotypes in barley. In 32 barley cultivars (lines) with unknown Yd2 genotype, the three markers revealed Yd2^-/Yd2^- genotype in 27 cultivars (lines) and Yd2⁺/Yd2⁺ genotype in the remaining five cultivars (lines). In a breeding practice aiming at BYDV resistance improvement, 16 positive plants with Yd2⁺/Yd2⁺ genotype were selected rapidly and successfully from the BC₂F₂ population using MAS approach. We suggest the cooperative application of the three markers in selecting Yd2 gene and genotype from a large scale of lines in barley backcross populations to ensure the accuracy and efficiency of MAS.

Proteomic Analysis of Plumule in Seed Germination for an Elite Hybrid of Pioneer 335 and Its Parental Lines in Maize

JIN Qian-Ning, FU Zhi-Yuan, DING Dong, LIU Zong-Hua, LI Wei-Hua, SHANG Ji-Hua

Acta Agron Sin. 2011, 37(09):  1689-1694.  doi:10.3724/SP.J.1006.2011.01689

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The plumule (including coleoptile) of seed cultured for 84 h was used as materials to analyze the proteomic difference between the elite hybrid Pioneer 335 and its parental lines by mean of 2-D electrophoresis method. The results showed that 560 protein spots were identified in Pioneer 335, 507 and 508 protein spots parental lines in its PH6WC and PH4CV, respectively. And in Pioneer 335, 81% protein spots exhibited nonadditive expression model. Out of them, 288 showed up-regulation with over high parent expression model. While only 15 showed down-regulation with over low parent expression model. Thus the accumulation of nonadditive expression protein might be the key factor resulting in heterosis at the tested development at stage in Pioneer 335 at least in this study. Notably, 13 significantly different protein spots between the hybrid and its parents were involved in metabolic pathway, protein folding, stress response, cytoskeleton and cell detoxification.

Male Sterility Induced by Chemical Hybridizing Agent SQ-1 in Setaria italica Beauv.

SONG Yu-Long, WANG Liang-Meng, ZHANG Gai-Sheng, CHENG Yang, LI E-Xin, NIU Na, ZHAO Zhuo-Jun

Acta Agron Sin. 2011, 37(09):  1695-1700.  doi:10.3724/SP.J.1006.2011.01695

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To explore a new way for utilizing heterosis in Setaria italica Beauv., three foxtail millet varieties, namely Wujiuzhuaruangu, Xianggu and Huangjingu, were used in this study. In three different developmental stages, we sprayed plant with three different concentrations of Chemical Hybridizing AgentSQ-1, and control plant with water. Results showed that male sterility rates in Wujiuzhuaruangu and Xianggu were from 95% to 100% under the proper spraying concentration at the specific developmental stage, and that in Huangjingu was lower than 90%. At seven leaf in Wujiuzhuaruangu and at eight leaf in Xianggu were the best developmental stages for spraying, two varieties had the same best spraying concentrations for best rate of male sterility, which was 5 kg ha^–1. In conclusion, the specific genotypes of foxtail millet at the suitable developmental stage can be induced 95–100% male sterility by spraying SQ-1 at an optimum dosage, which provides a theoretical basis of heterosis and new technical support for using CHA SQ-1 to produce hybrid foxtail millet.

Inheritance of Wet Gluten Content and Gluten Index in Wheat

TANG Jian-Wei, YAN Gui-Hong, WANG Li-Na, HAN Yu-Lin, HUANG Feng, XU Hai-Fei, YANG Guang-Yu, LI Xin-Beng

Acta Agron Sin. 2011, 37(09):  1701-1706.  doi:10.3724/SP.J.1006.2011.01701

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The objective of this study was to disclose the genetic mechanism of gluten quality in common wheat. Using seven wheat cultivars with different wet gluten contents (WGC) and gluten indices (GI), 21 crosses were obtained using the Griffing diallel cross II design. Among the parents, Xinmai 18 had large general combining abilities for WGC and GI, and the both WGC and GI were increased significantly in its hybrids. Parent Zhou 8425B had the highest WGC and its general combining ability was relatively large. The WGC of hybrid progenies from Zhou 8425 were significantly improved. However, the GI values of Zhou 8425B progenies were small, indicating that the dough quality of Zhou 8425B progenies was difficult to be improved. The inheritances of WGC and GI followed the additive–dominance–epitasis model with recessive loci for increasing GI and dominant loci for increasing WGC. Because GI is controlled by recessive genes and its narrow sense heritability is high, a relatively large population is recommended in early breeding generations and the phenotypic selection should not be too intensive. GI and WGC may be used in direct breeding of wheat quality.