Table of Content

12 June 2013, Volume 39 Issue 06

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REVIEW

Rhizobiological Properties of Allelopathic Rice in Suppression of Weeds and Its Research Prospect

LIN Wen-Xiong

Acta Agron Sin. 2013, 39(06):  951-960.  doi:10.3724/SP.J.1006.2013.00951

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Two reviewed areas of the research include the genetic physiological and molecular ecological characteristics, and the allelochemical identification, rhizospheric biological process and mechanism of rice allelopathy. As a quantitative trait, the allelopathy is mediated by both genetic and environmental factors. QTLs for allelopathy are found mainly on chromosomes 2, 3, 8, 9, and 10 significantly interacting with the additive×additive epistatic effects and the environment. However, no relevant study has been reported concerning the correlation between the QTL genetics and allelochemical synthesis. Phenolic acids, terpenoids and flavonoids have been identified in laboratory to be the metabolites showing allelopathic potentials on the target weed (barnyardgrass). Since a concentration higher than what is normally required to exhibit the allelopathic effect in rice rhizospheric soils for phenolic acids, some researchers questioned its association with the allelopathy. On the other hand, our studies indicated that the rice allelopathic potential was enhanced under stress from the increased phenolic acids in soil. Furthermore, the gene expression of phenylalanine ammonia-lyase (PAL-2-1) in the allelopathic rice, PI312777, was inhibited by the RNA interference (RNAi). The transgenic rice showed decreases in the phenolic acid concentration and the rhizospheric bacterial diversity as compared with its wild type (WT), especially for myxobacterium, whose population was significantly lowered. The results suggested that the phenolic acids might be regulated by PAL-2-1 gene, and then be released into the soil resulting in the chemotactic aggregation of the rhizosphere characteristic microbes. Some species of microorganisms with vast diversity existing in soil could conceivably degrade plant root exudates leaving little allelochemicals to be detected. The degradation and transformation by the rhizosphere microorganisms might have a coupling effect with the allelochemicals to result in the crop’s allelopathic effect on weeds as observed. Consequently, studying the rhizospheric biological process could eventually reveal the detailed mechanism of the rice allelopathy.

Research Advances and Prospects of Eating Quality Improvement in Japonica Rice (Oryza sativa L.)

XU Quan,TANG Liang,XU Fan,FUKUSHIMA Akira,HUANG Rui-Dong,CHEN Wen-Fu,XU Zheng-Jin

Acta Agron Sin. 2013, 39(06):  961-968.  doi:10.3724/SP.J.1006.2013.00961

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From the beginning of the 21st century, japonica rice area in the North China, especially in the Northeast China has expanded unceasingly, rice yield has increased significantly, and grain quality has been steadily improved. However, the improvement of eating quality is still one of the important research contents. We based on the research results of Japanese japonica rice, introduced the eating quality appraisal method and relationships rice starch type starch content, molecular structure, protein type and protein content, other material contents eating quality, as well as between eating quality and grain outer surface, and internal ultra structure. The genetic research advances of eating quality related traits and breeding application were also introduced. We believe that applied basic researches in breeding, cultivation and biotechnology for eating quality of japonica rice in Northeast China should be conducted. Fully using of indica rice with favorable genes of more secondary branch grains on upper panicles, more great vascular bundles in panicle neck and more primary branches and at the same time decreasing the bad influence on eating quality should be the important research subjects in North especially Northeast, on breeding between indica and japonica cross for good quality and high yield.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Analysis of Meta-QTL and Candidate Genes Related to Yield Components in Maize

IANG Pei-Shun1,2,**,ZHANG Huan-Xin2,**,Lü Xiang-Ling1,HAO Zhuan-Fang2,LI Bo1,LI Ming-Shun2,WANG Hong-Wei,CI Xiao-Ke,ZHANG Shi-Huang,LI Xin-Hai,SHI Zhen-Sheng,WENG Jian-Feng

Acta Agron Sin. 2013, 39(06):  969-978.  doi:10.3724/SP.J.1006.2013.00969

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In this study, 584 QTLs related to grain yield components (row number, kernel number per row and kernel weight) in maize were integrated from the published papers between 1994 and 2012 using the reference map of IBM2 2008 Neighbors high density maize genetic map. By Meta-analysis method, 73 Meta-QTLs for grain yield components were estimated, including 22QTLs for row number, 7 QTLs for kernel number per row and 44 QTLs for kernel weight. With the B73 genome sequences, 10 maize genes and 12 rice homologous candidate genes related to yield components were comparatively and electronically mapped in consensus map, andthese genes are located in maize chromosome Bins 1.04, 1.06, 1.07, 2.04, 2.06, 3.04, 4.05, 4.07, 4.09, 5.03, 5.04, 5.05, 7.02, 8.03, 9.03, 10.06 and 10.07. The analysis of Meta-QTL and candidate genes related to grain yield components will provide useful information for marker-assisted selection breeding and gene cloning in maize.

Genetic Evolution for Vigna Subgenus Ceratotropis Based on Chloroplast DNA Sequences

LIU Yan,CHENG Xu-Zhen*,WANG Li-Xia,WANG Su-Hua,BAI Peng

Acta Agron Sin. 2013, 39(06):  979-991.  doi:10.3724/SP.J.1006.2013.00979

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China has abundant germplasm resources of subgenus Ceratotropis, but the related study of species within this subgenus is much lagged. In order to investigate genetic relationship and evolution process among different species, 110 entries of Ceratotropis were analyzed by using intron rpl16, rps16 and intergenic regions psbA-trnH, rpoB-trnC, and trnL-trnF of chloroplast genome. The results revealed that parsim-info site percentage was from 3.63% to 24.28%, with the highest for rps16 and the lowest for rpoB-trnC. A higher level conservation of sequence was observed within species than inter-species. Kimura-2-parameter distance was between 0 and 0.057 calculated based on five chloroplast assembling sequences. V. minima complex (including V. minima, V. riukinensis and V. nakashime) and V. subramaniana had the longest distance. Phylogenetic trees constructed by neighbor-joining (NJ) and maximum parsimony (MP) methods in MEGA 5.1 and PAUP 4.0 revealed that eighteen species and subspecies were divided into two branches. The group I contained nine species and subspecies grouped into three sections complex, including Angulares, Ceratotropis and Aconitifoliae. The group II contained nine species and subspecies which completely belonged to section Angulares. Partition homogeneity test of phylogenetic trees of the five sequences showed that their topology was highly consistent (P=0.87). The present study provides the important information for clarifying genetic relationship Ceratotropis. among different species within

Identification and Gene Mapping of Leaf Pale Yellow-Revertible Mutant pyr1 in Rice

CHENG Xin,REN De-Yong,MA Jiao,ZHU Xiao-Yan,SANG Xian-Chun,LING Ying-Hua,ZHAO Fang-Ming,HE Guang-Hua*

Acta Agron Sin. 2013, 39(06):  992-998.  doi:10.3724/SP.J.1006.2013.00992

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It is important for the further understanding of the relationship between chlorophyll synthesis and degradation pathways and plant photosynthesis to identify and clone leaf color mutant gene. A leaf pale yellow-revertible mutant temporarily designated as pyr1 was obtainted from the progeny of rice (Oryza sativa L.) restorer line Jinhui 10 which was induced by ethyl methane sulfonate (EMS). In the seedling stage, the whole leaf of mutants presented pale and some mutants died. The pyr1 displayed different colors in different growth periods. At the booting stage upper-leaf and leaf margin exhibited yellow. Compared with the wild type, the chlorophyl contents of pyr1 mutant decreased from seedling stage to filling stage. Transmission electronic microscopy observation showed that the structure of cells had no obvious differences between mutant and wild type, but the chloroplast developed abnormally with degradation of the inside and matrix slices. Genetic analysis revealed that the trait was controlled by one recessive gene. With 326 recessive individuals from the F₂ segregation population, the PYR1 gene was finally mapped between RM11722 and Ind1 on the long arm of chromosome 1, with an approximate physical distance of 92 kb. These results provide a basis of PYR1 gene cloning by map-based strategy.

Reaction of Wheat-Thinopyrum Progenies and Wheat Germplasm to Sharp Eyespot

LI Hong-Jie,WANG Xiao-Ming,CHEN Huai-Gu,LI Wei,LIU Dong-Tao,ZHANG Hui-Yun

Acta Agron Sin. 2013, 39(06):  999-1012.  doi:10.3724/SP.J.1006.2013.00999

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The objectives of this study were to test reactions of wheat-Thinopyrum derivatives and wheat (Triticum aestivum L.) cultivars and breeding lines to sharp eyespot (caused by Rhizoctonia cerealis Van der Hoeven) and to understand the relationship between Thinopyrum chromosomes and sharp eyespot resistance. Using field nursery tests, 321 common wheat accessions and 56 wheat-Thinopyrum derivatives were tested in Xuzhou and Nanjing, Jiangsu Province, China. In Xuzhou, none of the accessions was highly resistant, while 52 accessions (including 34 common wheat accessions) were moderately resistant. Six common wheat cultivars, i.e., Xiaonong 8506-1, Xiaoyan 81, Jizhi 4001, Nongda 195, Xuzhou 8913, and Jingdong 3066A-3, had the relative resistance index greater than 0.7. In Nanjing, all the common wheat entries were moderately or highly susceptible. Only five accessions in wheat-Thinopyrum progenies showed moderately resistant reaction. The chromosome addition, substitution, and translocation lines TA3513, TA3516, TA351, and TA3519 involving chromosome 4Ai#2 or 4Ai#2S of Th. intermedium and the chromosome substitution line SS767 involving homoeologous group 4 chromosome of Th. ponticum had the disease indexes smaller than the susceptible controls Sumai 3 and Yangmai 158, as well the moderately resistant controls Annong 8455 and Ningmai 9. This indicated that the homoeologous group 4 chromosomes from Th. intermedium and Th. ponticum were most likely associated with the reduction of disease indexes. Genomic in situ hybridization using St genomic DNA from Pseudoroegneria strigos as a probe demonstrated that chromosome 4Ai#2 belongs to J^s genome of Th. intermedium and the homoeologous group 4 chromosome of Th. ponticum belongs to J genome. Although sharp eyespot and eyespot develop similar shapes of symptoms on the basal stems of wheat, the eyespot resistance genes Pch1 and Pch2 carried by the wheat cultivars Madsen and Cappelle-Desprez, respectively, were not effective against sharp eyespot.

Phenotypic Analysis and Molecular Characterization of Two Allelic Mutants of the D2 Gene in Rice

IN Yan-Ling,YIN Liang,ZHAO Jin-Feng,SUN Wei,ZHAO Qing-Lei,YUAN Shou-Jiang,ZHU Wen-Yin,GUO Bao-Tai,LI Xue-Yong

Acta Agron Sin. 2013, 39(06):  1013-1020.  doi:10.3724/SP.J.1006.2013.01013

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Two dwarf mutants s1-46 and s1-96 were isolated from an EMS mutated japonica cultivar Nipponbare. The plant height of the two mutants was 44.7% and 55.9% of that of the wild-type plant, respectively. The mutants also exhibited erect leaves, reduced grain number,,and shortened grains. When grown in complete darkness, the mesocotyl elongated in the wild-type plant, but not in the mutants, indicating that s1-46 and s1-96 are brassinosteroids (BRs)-related mutants. Furthermore, treatment of seedling with bioactive BR showed that the leaf angle was increased and the root length was decreased in both the wild-type and mutant plants, suggesting that the mutated gene is involved in BR biosynthesis. Genetic analysis showed that the phenotypes of both mutants were caused by a recessive gene. Fine-mapping showed that this gene was located within a 40.9 kb region on chromosome 1. Sequence analysis revealed that the mutated gene was allelic to D2, encoding CYP90D2that is involved in BR biosynthesis. In s1-46 and s1-96, the encoded amino acids were changed from proline to leucine and from glycine to glutamic acid at the 305th and370thpositions of D2, respectively.

Analysis of Related Interactions and Mapping of QTLs for Seed Weight per Plant in Soybean in Different Years

FAN Dong-Mei,MA Zhan-Zhou,LIU Chun-Yan,YANG Zhe,ZENG Qing-Li,XIN Da-Wei,JIANG Hong-Wei,QIU Peng-Cheng,CHEN Qing-Shan,HU Guo-Hua

Acta Agron Sin. 2013, 39(06):  1021-1029.  doi:10.3724/SP.J.1006.2013.01021

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QTL analysis of seed weight per plant, epistatic effects and the QE interaction, have a great contribution tothe promote study of genetic for seed weight per plant in soybean. The objective of this study was to investigate the major QTLs, epistatic effects, and QE interaction effects of QTLs for seed weight per plant in soybean. To find out the steady and repeatable QTLs of this trait, we used F_2:14–F_2:18 RIL population containing 147 lines in this experiment in two sites in five years by CIM and MIM. Seventeen QTLs for seed weight per plant were detected by CIM and MIM in D1a, B1, B2, C2, F, G, and A1 linkage groups, respectively, accounting for 6.0–47.9% of the general phenotypic variation. Three QTLs for seed weight per plant could be detected simultaneously by CIM and MIM, accounting for 6.3%–38.3% of the general phenotypic variation. Four QTLs for seed weight per plant could be detected simultaneously in more than two years, accounting for 8.1–47.9% of the general phenotypic variation. Data from seven environments were used to detecte by QTLMapper for QE interaction effects and epistatic effects of QTLs in this study. One QE QTL and four pairs of QTLs with epistatic effects were detected, but the additive effects contribution rate and the general contribution of interaction were not significant, indicating that both major and minor QTLs with epistatic effects and QE should be considered in the improvement in soybean breeding.

Screening and Molecular Identification of Resistance to Powdery Mildew in Pea Germplasm

WANG Zhong-Yi,BAO Shi-Ying,DUAN Can-Xing,ZONG Xu-Xiao,ZHU Zhen-Dong

Acta Agron Sin. 2013, 39(06):  1030-1038.  doi:10.3724/SP.J.1006.2013.01030

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Pea powdery mildew, caused by Erysiphe pisi, is one of the most important diseases in pea production. The utilization of resistant pea cultivars is the most economical and effective method for controlling the disease. In this study, Three hundred and ninety-six pea accessions were evaluated for resistance to two powdery mildew isolates from different geographical origins in seedling stage under controlling condition, and four SCAR makers closely linked to pea powdery mildew resistance gene er1 were used to genotype accessions with immunity or resistance. The results showed that 101 accessions were immune or resistant to powdery mildew, 59 (14.9%) and 60 (15.2%) accessions were immune to the Beijing isolate and Yunnan isolate, respectively, 54 (13.6%) accessions were immune to both the Beijing isolate and Yunnan isolate. In eighty-two accessions from China, only eight were immune to both of the two isolates. Thirteen marker genotypes were identified in 66 selected accessions with immunity or resistance through molecular genotyping, and the accessions from the same geographical origin contained different marker genotypes. Eight accessions from Yunnan Province of China shared seven marker genotypes. The above results indicated that pea germplasm with resistance to pea powdery mildew has effective and extensive genetic diversity in China.

Genetic Analysis and Gene Mapping of a degraded hull 2 (dh2) Mutant in Rice (Oryza sativa)

GUO Shuang,LI Yun-Feng,REN De-Yong,ZHANG Tian-Quan,HE Guang-Hua

Acta Agron Sin. 2013, 39(06):  1039-1044.  doi:10.3724/SP.J.1006.2013.01039

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The identification and cloning of novel mutant genes of floral organ in rice play an important role in understanding the molecular genetic mechanisms and molecular signal pathways regulating floral organ development. A rice mutant, degraded hull 2(dh2), which was derived from ethylmethane sulfonate (EMS)-treated Jinhui 10 (Oryza sativa), exhibited defects in hull development. The dh2 floretsdisplayed open hull in whorl 1, however, the rest floral parts in other three whorls had no obvious change. Further analysis indicated that the number of transverse cells decreased, making the lemma or palea narrow, and causing the hull open. The genetic analysis revealed that the dh2 trait is controlled by a single recessive gene. Using the BSA method, the DH2 gene was finally mapped between IND-5 and IND-14 on chromosome 3 with geneticdistances of 0.99 cM and 1.49 cM, respectively. These results are useful for the map-based cloning of DH2 gene, and very important in the studies of floral development biology.

In silico Expression Profile of Genes in Response to Drought in Peanut

SUN Ai-Qing,ZHANG Jie-Dao,WAN Yong-Shan,LIU Feng-Zhen,ZHANG Kun,SUN Li

Acta Agron Sin. 2013, 39(06):  1045-1053.  doi:10.3724/SP.J.1006.2013.01045

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Drought, one of the most important abiotic stresses, usually causes adverse effects on the productivity and quality of crops. In this study, a drought-resistant variety Fenghua 5 was used to analyse leaf cDNA library of peanut treated with 15% PEG by Solexa high-throughput technology, and detect the differentially expressed genes under drought stress. The results of Solexa sequencing indicated the gene expression in peanut transcriptome presented strong nonhomogeneity and redundancy. The sequenced tags less than 10 copies accounted for 73.1% of the total tag types, however its expression level only accounted for 9.0% of the total. A total of 935 differentially expressed genes were screened out based on the reference tags, of which 64.5% were down-regulated. These differentially expressed genes were involved in metabolisms of carbohydrate, protein, nucleic acid, lipid and energy, and secondary metabolism. Gene expression analysis of peanut also showed that nine transcripts related to flavonoid metabolism significantly up-regulated under drought stress, including four encoding flavonoid biosynthesis enzymes, three encoding methyltransferase and two encoding MYB transcription factor. The gene expression analysisusing semi-quantitative RT-PCR assays indicated that AhPAL was induced significantly by 15% PEG treatment for 6 h. The result showed that flavonoids metabolism might play an important role in peanut responding to drought stress.

Excavation and Characterization of Novel Rice 57H Mutants

CHE Qian-Qian,GUO Yan-Ping,LI Qiang,WANG Yi-Hua,WANG Guang-Yuan,TIAN Huai-Dong

Acta Agron Sin. 2013, 39(06):  1054-1059.  doi:10.3724/SP.J.1006.2013.01054

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Glutelins and prolamins, the main rice storage proteins, are synthesized in the ER and accumulated into the vacuolar protein body and the ER-derived protein body in endosperm cell of the developing seed of the wild type rice, respectively. Several 57H mutations have been found to cause the high increase of 57 kD glutelin precursor and the remarkable decrease of the mature glutelins, and involved in the accumulation of storage proteins in rice. In this study, two 57H mutants were newly found and obtained from rice germplasms using SDS-PAGE technique. SDS-PAGE analysis of the total seed proteins showed that the two mutants had the characters namely the great increase of 57 kD polypeptide and the lack of 13 kD polypeptide, but not alteration of characters for the mature glutelins and other storage proteins; Electrophoretic and immuno-blotting analyses of glutelin showed that the increased polypeptides was 57 kD glutelin precursor in the mutants; Electrophoretic analysis of prolamins showed that the lacked polypeptide was 13kD prolamin in them. It is indicate that the two mutants have novel characters distinct from the reported 57H mutants. They probably contain unknown genetic information for synthesis and expression of storage proteins, and are considered to be useful materials for the overall understanding of genetic mechanism regulating synthesis and accumulation of the storage proteins in rice.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of High Temperature Stress on PSII Function and Its Relation to D1 Protein in Chloroplast Thylakoid in Rice Flag Leaves

YANG Wei-Li,HUANG Fu-Deng,CAO Zhen-Zhen,LEI Bing-Ting,HU Dong-Wei,CHENG Fang-Min

Acta Agron Sin. 2013, 39(06):  1060-1068.  doi:10.3724/SP.J.1006.2013.01060

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On the basis of the artificial controlled temperature treatments in growth chambers, influences of high temperature stress at rice filling stage on the expression and distribution of D1 protein in leaf chloroplast thylakoid, as well as their relations to the decline of leaf photosynthetic rate and the damage of PSII membrane system were investigated by detecting the temporal pattern of leaf photosynthetic rate and chlorophyll fluorescence parameters, with SDS-PAGE electrophoresis, western-blotting and immunogold labeling methods. The results showed that rice flag leaves exposed high temperature generally had lower net photosynthetic rate (P_n), PSII potential efficiency(F_{v/Fo) and solar energy transmitting efficiency(Fv/Fm) compared with those under normal temperature, with more severe damage and remarkable function dropping in chloroplast thylakoid due to prolonging stress times and accelerating leaves senescence.The amount of D1 protein in rice leaves under high temperature stress decreased significantly. In the two types of D1 protein, the amount of non-phosphorylated D1 protein was more sensitive to high temperature stress than the phosphorylated D1 protein.The RNA transcription of psbA gene in chloroplast, controlling D1 protein synthesis, was down-regulated by high temperature stress, inhabiting mRNA transcription and protein translation in D1 protein synthesis, thereby causing the functional damage of PSII reaction centre in thylakoid and dropping leaf photosynthetic rate under high temperature stress. It could be suggested that the functional damage of PSII reaction centre under high temperature stress be caused by the combined action of D1 protein hosphorylation and psbA gene expression, resulting in the decrease of photosynthetic rate and high temperature tolerance in two rice genotypes.}

Yield Performance Characteristics and Regulation Effects of Plant Density and Sub-Soiling Tillage System for High Yield Population of Summer Maize

HOU Hai-Peng,DING Zai-Song,MA Wei,LI Cong-Feng,ZHAO Ming

Acta Agron Sin. 2013, 39(06):  1069-1077.  doi:10.3724/SP.J.1006.2013.01069

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A 2-year field trial using high yield varieties Zhengdan 958 and Zhongdan 909 with densities and tillage systems was conducted in Xinxiang, Henan Province during 2010–2011 growing season to study the characteristics of yield performance parameters and the effect of main cultivation practices for high yield population Results indicated that compared with Zhendan 958, Zhongdan 909 increased grain yield by 11.36% significantly, as well as kernel number per ear (KN) and 1000-kernel weight (KW) (P<0.01). There was no difference (P>0.05) in duration (D), harvest index (HI), and ear number (EN) between two hybrids. Mean leaf area index (MLAI) and leaf area duration were improved significantly (P<0.01), mean net assimilation rate (MNAR) was increased significantly (P<0.05). Moreover, Zhongdan 909 retained higher maximum growth rate,biomass at the maximum growth rate,average growth rate and active growth duration compared with Zhengdan958. There were significantly positive correlations between EN and MLAI (P<0.01), and between KN, KW, and MNAR (P<0.01). There were significantly negative correlations between MNAR, KN, KW, and MLAI (P<0.01). Zhongdan 909 had a higher yield because of the mechanism of asynchronous improvement of yield performance parameters. The optimize population of Zhongdan 909 was 27.3% higher than that of Zhengdan 958, with the higher MLAI, MNAR and KN. Grain yield increased by 8.71% and 13.02% in sub-soiling tillage system for Zhengdan 958 and Zhongdan 909, respectively, resulting from increasing MNAR and KN significantly. There was no difference in MLAI and D between both varieties. HI, EN and KW were increased differently in different varieties. Thus, yield performance parameters for high yield of 11 250–12 000 kg ha^-1 were MALI 3.05–3.55, MNAR 4.80–6.27 g m^-2 d^-1, growth days 109–111, harvest index 0.50–0.52, harvest ears 9.60–10.38×10⁴ ha^-1, kernel number per ear 352.0–370.1, 1000-kernel weight 314.7–315.9 g. Increasing population density (about 9.50×10⁴ plants ha^-1) with sub-soiling tillage system is one of main management practices for high yield in Yellow Huai Valley areas.

Effect of 6-BA and ABA Applications on Yield, Quality and Photosynthate Contents in Subtending Leaf of Cotton with Different Planting Dates

LIU Jing-Ran,LIU Jia-Jie,MENG Ya-Li,WANG You-Hua,CHEN Bing-Lin,ZHANG Guo-Wei,ZHOU Zhi-Guo

Acta Agron Sin. 2013, 39(06):  1078-1088.  doi:10.3724/SP.J.1006.2013.01078

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To study the effects of 6-BA and ABA applications on carbohydrate contents and endogenous hormones in subtending leaf, and their relationship to cotton yield and qualities under different planting dates, we conducted a field experiment with two cotton cultivars Kemian 1 and NuCOTN 33B in the Lower Reaches of Yangtze River (Nanjing) and in the Yellow River Valley (Anyang), China. The cotton seeds were planted on Apr. 25th and May 25th, 2006, respectively, which could result in different growth temperatures for the bolls and their subtending leaves at the same site, and the growth regulators were sprayed at flowering stage. The results showed that the application of 6-BA significantly increased contents of sucrose and starch, and sucrose transformation rate in subtending leaf, while the application of ABA only regulated the balance of endogenous hormones. The application of 6-BA increased boll weight and enhanced fiber qualities in cotton plants with planting dates of Apr. 25th and May 25th, whereas the decrease ranges of cotton yield and qualities in Anyang were less for the application of ABA in cotton plants with planting date of May 25th, compared to those with planting date of Apr. 25th. However, the qualities of cottonseeds were not affected by the applications of 6-BA or ABA significantly. The application of 6-BA or ABA improved relative cotton qualities of late planted cotton, whereas the action mechanisms were different. The application of 6-BA improved cotton yield and quality via enhancing the photosynthate contents and sucrose transformation rate. However, the application of ABA improved cotton yield and qualities via increasing the stress resistance of cotton plants.

Effects of Clomequat-Uniconazole 30% Micro-Emulsion on Stem Physical and Chemical Characteristics of Rice

ZHANG Qian,ZHANG Ming-Cai,ZHANG Hai-Yan,TAN Wei-Ming,LI Zhao-Hu,DUAN Liu-Sheng

Acta Agron Sin. 2013, 39(06):  1089-1095.  doi:10.3724/SP.J.1006.2013.01089

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Lodging is one of the most restrictive factors of cold ground rice to achieve higher yield. Using a cultivars Kendao 12 at the early jointing sprayed with a new plant growth regulator 30% chlormequat-uniconazole ME, we studied the effect of it on morphological and physiological characteristics, yield and yield components. The results indicated that 1.2 L ha^-1 treatment of 30% chlormequat-uniconazole ME on rice leaves could markedly shorten the length of basal internodes and increase the diameter of them. In addition, cell microscopy showed that tight degree of cell in 1.2 L ha^-1 treatment was enhanced, and the cells got shorten. Through the improvement of stem morphological characteristics, the bend breaking strength and radial compressive strength were respectively increased by 152.4% and 82.5% as compared with CK. The plant growth regulation could significantly increase the C/N value in the basal internode of stem at full-heading stage; increase contents of hemicellulose, cellulose and lignin of stem at later grain filling stage; significantly reduce GA₃ content in the 2nd internodes; and improve rice yield and its components. Generally speaking, 30% chlormequat-uniconazole ME can enhance the quality of stem to improve lodging-resistance of rice.

Effects of Exogenous ABA and 6-BA on Flag leaf Senescence in Different Types of Stay-Green Wheat and Relevant Physiological Mechanisms

YANG Dong-Qing,WANG Zhen-Lin*,YIN Yan-Ping,NI Ying-Li,YANG Wei-Bing,CAI Tie,PENG Dian-Liang,XU Cai-Long,CUI Zheng-Yong,LIU Tie-Ning,XU Hai-Cheng

Acta Agron Sin. 2013, 39(06):  1096-1104.  doi:10.3724/SP.J.1006.2013.01096

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The effects of exogenous abscisic acid (ABA) and 6-benzyladenine (6-BA) on the contents of chlorophyll, malondialdehyde (MDA), and endogenous hormones and activities of antioxidant enzymes in flag leaf were investigated using stay-green wheat cultivar Wennong 6 and a control cultivar Jimai 20. The results showed that ABA and 6-BA obviously increased chlorophyll content from seven days after anthesis (DAA) to twenty-eight DAA. Likewise, the soluble protein contents in ABA-treated and 6-BA-treated plants significantly increased from 21 DAA to 35 DAA, while the MDA content decreased from 28 DAA to 35 DAA. Although ABA applications decreased endogenous zeatin (ZR) and ABA contents from 28 DAA to 35 DAA, the endogenous auxin (IAA) and gibberellin (GA) contents increased. In both cultivars, 6-BA significantly increased the ZR content, but decreased the ABA content in Jimai 20 from 21 DAA to 35 DAA. Exogenous ABA and 6-BA significantly enhanced superoxide dismutase (SOD) activity, while had no significant effects on peroxidase (POD) and catalase (CAT) activities in Wennong 6 and increased POD activity in Jimai 20 from 7 DAA to 28 DAA. Exogenous 6-BA significantly increased POD and CAT activities in both cultivars. Meanwhile, treatments with ABA and 6-BA significantly increased 1000-grain weight and yield, that had no effects on grain number per spike and spike number per square meter.

Variation of Priestley-Taylor Model Parameter in Rain Fed Spring Maize Field

GUO Jia-Xuan,MEI Xu-Rong,LI Qiao-Zhen,YAN Chang-Rong,LI Yu-Zhong

Acta Agron Sin. 2013, 39(06):  1105-1110.  doi:10.3724/SP.J.1006.2013.01105

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The study on Priestley-Taylor (PT) reference crop evapotranspiration model coefficient (α) in local area is of great significance in semi-arid agricultural water resources efficient use and precision irrigation in corn. Here, based on the FAO (1998)-recommended Penman-Monteith (PM) reference crop evapotranspiration as a standard method, we determined the water and heat exchange and its estimated parameters by the eddy covariance technique and Priestley-Taylor model under local climatic conditions. The results indicated that the estimated values of reference crop evapotranspiration (ET_{0-PT 1.26}) gained from PT model-recommended coefficient (α = 1.26) lowed by 21.2% on an average during non-growth stages (from November to April next year), and reached an average of 5.5% higher than those from PM model reference crop evapotranspiration (ET_0-PM) from May to September. The local PT model coefficient α value was 1.15 ± 0.06. The average PT model coefficient at noon during growth stages showed a single peak changing trend with the highest value of 0.67 ± 0.08 from tasseling to flowering stage and with the lowest value of 0.26 ± 0.13 at seedling stage. In conclusion, if the reference crop evapotranspiration is necissery to be estimated accurately by PT model in the semi-arid climate area, the local PT parameters should be studied firstly.

Effects of Exogenous Hormone 6 Benzyl Adenine (6-BA) on Photosystem II (PSII) Performance of Maize during Process of Leaf Senescence under Different Nitrogen Fertilization Levels after Anthesis

CHEN Xiao-Lu,LI Geng,LIU Peng,GAO Hui-Yuan,DONG Shu-Ting,WANG Zhen-Lin,ZHANG Ji-Wang,ZHAO Bin

Acta Agron Sin. 2013, 39(06):  1111-1118.  doi:10.3724/SP.J.1006.2013.01111

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A two years experiment was conducted using maize inbred line Qi 319 with different nitrogen fertilization levels and exogenous hormone 6 benzyl adenine (6-BA) treatments. The results demonstrated that the chlorophyll content and net photosynthetic rate (P_n) were gradually decreased after anthesis. In treatments of 6-BA without nitrogen fertilizer, chlorophyll contents were increased significantly, but P_n showed no significant increase, and the activity of PSII reaction center was not increased. Under the condition of applying nitrogen fertilizer, P_n and the activity of PSII reaction center were increased significantly, and based on nitrogen fertilizer used, the 6-BA could improve the response of P_n and performance of PSII to nitrogen fertilizer effectively. Under the nitrogen fertilizer and 6-BA interaction conditions, the chlorophyll content and P_n were increased significantly (P<0.05), the activities of donor site and acceptor site of PSII were increased significantly, and the donor site was improved more than that of acceptor site. The most obvious improvement of the activity of PSII reaction center was appeared at the 10^th day after anthesis. The improvement of photosynthetic performance significantly improved the single plant dry matter accumulation and grain yield (P<0.05). In conclusion, spraying plant with 6-BA under suitable application of nitrogen fertilizer can significantly improve the photosynthetic performance of maize leaf.

RESEARCH NOTES

cDNA-SCoT Analysis of Differentially Expressed Genes in Sugarcane Induced by Leifsonia xyli subsp. xyli

CHEN Ming-Hui,ZHANG Bao-Qing,SONG Xiu-Peng,CHEN Hu,YANG Li-Tao,LI Yang-Rui,CHEN Bao-Shan

Acta Agron Sin. 2013, 39(06):  1119-1126.  doi:10.3724/SP.J.1006.2013.01119

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Ratoon stunting disease (RSD) is one of the major diseases, which is harmful to sugarcane in the world. To investigate the molecular mechanism of gene differential expression in sugarcane under ratoon stunting disease stress, we inoculated the stem of sugarcane variety ROC22 with cane juice with RSD pathogen Leifsonia xyli subsp. xyli to induce resistance, then took stem samples at 2, 4, 6, 8, and 10 days, respectively, after inoculation, and established different cDNA mixture pools transcribed from the stem RNA mixture pools of RSD treatment and control for cDNA-SCoT analysis to detect the gene differential expressions. More than 500 bands with length of 100–1800 bp were obtained using 80 SCoT primers. A total of 30 differentially expressed EST sequences were screened out, and 22 non-redundant ESTs with high quality were obtained by cluster analyses of the ESTs sequencing. The results of BlastN showed that the differentially expressed genes of ROC22 mainly related to energy metabolism, disease defense, signal transduction, and protein metabolism. Further analysis of gene function indicated that brassinosteroid biosynthesis-like proteins, NBS-LRR type disease resistance protein, jasmonic acid induced protein, α-tubulin, abscisic stress ripening protein, proline-rich protein, and translation initiation factor eif-2b α subunit may be involved in the process of the incompatible interaction between plants and Leifsonia xyli subsp. xyli.

Embryonic Development and Changes of Endogenous Hormones in Interspecific Hybrids between Peanut (A. hypogaea L.) and Wild Arachis Species

ZHANG Xin-You,XU Jing,TANG Feng-Shou,DONG Wen-Zhao,ZANG Xiu-Wang,ZHANG Zhong-Xin

Acta Agron Sin. 2013, 39(06):  1127-1133.  doi:10.3724/SP.J.1006.2013.01127

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The peanut cultivar Yuhua 15 was used as female parent to cross with wild species A. correntina and A. macedoi, respectively, with intervarietal cross Yuhua 15 × Baisha 1016 as check. There were no significant differences observed in pegging percentage among all the crosses. It indicated normal fertilization in the interspecific crosses. Embryo development was observed through paraffin sections, and contents of endogenous hormones including IAA, GA₃, ZR+DHZR, and ABA in the developing embryos of hybrids were determined with ELISA. In comparison with normal seed development of Yuhua 15×Baisha 1016 and Yuhua 15×A. correntina, Yuhua 15×A. macedoi was incompatible due to a deterred embryo development at approximately 12–17 days after pollination followed by the hyperplasia of integument into the embryo sac which suppressed further development of the embryo and finally resulted in abortion. Compared with two compatible crosses, the ABA content and ratios of ABA to total of other auxin in developing embryos of cross (Yuhua 15×A. macedoi) were relatively higher at the early development stage, while the contents of IAA, GA₃, and ZR+DHZR remained at a relatively lower level, which speculates on that abnormal hormone activities may be an important reason leading to the abortion of hybrid embryos. Peg bases of Yuhua15×A. macedoi were treated with IAA, KT, or mixture of the two, showing that the exogenous hormones can increase the length of ovule.

Construction of a Genetic Linkage Map in Flax (Linum usitatissimum L.)

WU Jian-Zhong,HUANG Wen-Gong,KANG Qing-Hua,ZHAO Dong-Sheng,YUAN Hong-Mei,YU Ying,LIU Yan,JIANG Wei-Dong,CHENG Li-Li,SONG Xi-Xia,ZHAO Qian,WU Guang-Wen,GUAN Feng-Zhi*

Acta Agron Sin. 2013, 39(06):  1134-1139.  doi:10.3724/SP.J.1006.2013.01134

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Using a population with 30 F₂ individuals from a cross between DIANE (cultivar for fibre) and NINGYA 17 (cultivar for oil) was established flax genetic linkage map with 71 SRAP primers and 24 SSR primers. The map contained 12 linkage groups which spanned a total map length of 546.5 cM, with four to five marker loci per linkage group. The markers on the map distributed evenly in the 12 linkage groups with an average distance of 5.75 cM between loci. The map merely covered a narrow range of the flax genome and needed further improvement. The results showed that the codominant markers in SRAP and SSR were more suitable for the construction of genetic map in flax. Constructing a integrated genetic linkage map of the whole genome in flax provides important informations for future molecular biology research in flax.