Table of Content

12 October 2011, Volume 37 Issue 10

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Analysis on Phenotypic Relationship between Roots and Important Shoot Agronomic Traits Using a RIL and Two Derived Backcross Populations of Super Rice Xieyou 9308

LIANG Yong-Shu, ZHAN Xiao-De, GAO Zhi-Jiang, LIN Ze-Chuan, SHEN Xi-Hong, CAO Li-Yong, CHENG Shi-Hua

Acta Agron Sin. 2011, 37(10):  1711-1723.  doi:10.3724/SP.J.1006.2011.01711

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A RIL population of Xieyou 9308 and two derived backcross populations derived from the RIL backcrossing with its recurrent parents were used in this study. Morphological traits were investigated including seven root parameters and ten shoot parameters under water culture and field experiment, respectively. Thephenotypic correlation between root traits and shoot traits was analyzed within XBR, RIL, and ZHR populations, carried out by ANOVA and correlation analysis utilizing DPS software. In both environments, the two recurrent parents showed significant difference in all traits. Transgressive-segregation and continuous distribution for all the traits were observed in three populations under two conditions. The root length (RL) correlated positively with five root traits including total root length (TRL), dry root weight (DRW), root surface area (RSA), root volume (RV), number of root tip (RT). However, the correlations between root diameter (RD) and the other six traits were negative. Six shoot agronomic traits including heading date (HD), plant height (PH), panicle length (PL), grain yield per plant (GYPP), number of spikelets per panicle (SPP), and grain setting density (GSD) showed a significantly positive correlation with theroot traitswhile the other four aboveground traits correlated with root traits negatively. All the ten shoot traits correlated with RD negatively. The goal of this work was therefore to provide some reliable information for hybrid breeding, and an useful selection criteria for super rice combination based on root morphological traits.

Analysis of Gene Glyma13g21630 Diversity in Cultivated (G. max) and Wild (G. soja) Soybeans

ZHANG Le, LI Yang-Hui, LIU Zhang-Xiong, QIU Li-Juan

Acta Agron Sin. 2011, 37(10):  1724-1734.  doi:10.3724/SP.J.1006.2011.01724

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Glyma13g21630 from soybean is homologous with a gene related to leaf size from Arabidopisis thaliana, and it experienced man-made selection during domestication in small sample test. This paper aims at analyzing single nucleotide polymorphism of Glyma13g21630 in large sample test and providing the foundation for tracing back to soybean domestication and analyzing the genetic basis of domesticated traits. According to Sanger method, PCR products of Glyma13g21630 from 49 wild soybean and 84 cultivars (including 46 landraces and 38 cultivars) were sequenced. The distribution patterns of single nucleotide polymorphism (SNP) for Glyma13g21630 were summarized. Using DNAStar, Mega, DNAsp and Tassel software tools, a total of 29 polymorphism sites were identified, which included 22 SNPs and seven InDels with frequencies of 1SNP/138 bp and 1InDel/434 bp, respectively. There were rich regions for nucleotide variation in intron three and intron five and less variations in other regions. Haplotype analysis indicated that the number of polymorphic loci was reducing from wild soybean to cultivated soybean, and the distribution range was correspondingly narrowed. Linkage disequilibrium analysis demonstrated that 42.86% of SNP sites in wild soybean were at significant linkage disequilibrium levels. The high ratio of Ka/Ks illustrated that some sites suffered strong positive selection pressure, which resulted in the reduction of polymorphism. The favored variation of Glyma13g21630 has been fixed in cultivated soybean, showing a bottleneck effect simultaneously.

Isolation and Analysis of AGAMOUS Homologous Gene and Its Promoter from Vicia sativa L.

ZHANG Lei, LIU Zhi-Feng, WANG Pan-Rong

Acta Agron Sin. 2011, 37(10):  1735-1742.  doi:10.3724/SP.J.1006.2011.01735

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Common vetch (Vicia sativa L.) is considered to be an idealliquidity spring proteid forage for Tibet stockbreeding. However, little has been known about the molecular mechanism of floral organ formation and subsequent seed development process during domestication of common vetch in alpine steppe. AGAMOUS(AG)gene is one of the most important floral homologous genes involved in plant stamen and gynoecium development. In this study, an AG homologue gene and its upstream regulation sequence were isolated from Vicia sativa L. using hiTAIL-PCR, RACE, and RT-PCR. The results showed that this gene was 3 158 bp in DNA sequence, coding a protein product of 244 animo acides. Homological analysis showed that the similarity between this sequence and Pisum sativum PsAG gene was over 98% in animo acid level. Therefore, the sequence was considered to be Vicia sativa AG gene. It was named VsAG with the accession number JF313850 in GenBank. By analysing the cis-elements existing in upstream promoter region and the second intron, the results showed VsAG second intron region shared some similar cis-elements with promoter region. It indicated the second intron of VsAG gene may play an important role in gene expression regulation.

Cloning and Functional Analysis of Viviparous-1 Promoter in Wheat

SUN Yong-Wei, NIE Li-Na, MA Wei-Zhi, XU Zhao-Shi, JIA Lan-Qin

Acta Agron Sin. 2011, 37(10):  1743-1751.  doi:10.3724/SP.J.1006.2011.01743

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Viviparous1 (Vp1) plays an important role in regulating embryo development, seed dormancy, and germination in higher plants. Although we previously demonstrated a close correlation between Vp1B allelic variation and the different levels of tolerance to pre-harvest sprouting (PHS) in common wheat, little is known about the potential cis-elements in Vp1B promoter region, which may be involved in the control of PHS by Vp1B. In this study, a 2 232 bp Vp1B upstream sequence was isolated. In silico analysis revealed the presence of nine ABRE, two DREB, six MYB, three GARE, one TCA-E, two TGACG-motif, four SKn-1, and one RYREPE cis-elements in the isolated sequence.Based on this, we constructed various plasmid vectors with 5′-truncated Vp1B promoters fused with the GUS (encoding β-glucuronidase) reporter gene. Transient expression assay in wheat callus indicated that Vp1B promoter activity was inducible by low-temperature, ABA, or GA treatment. However, the level of induced GUS activity declined as promoter length decreased. Subsequently, six truncated promoter reporter fusions were introduced into the genome of durum wheat by Agrobacterium-mediated transformation and stable transgenic lines were obtained. Analysis of the transgenic lines indicated that Vp1B promoter could drive GUS expression in the anther, axis,aleurone and root, but not in the leaves, stems and nodes. However, in the plants with the transgenic Vp1B promoter fragment longer than 660 bp, GUS expression could be induced in the nodes by ABA treatment.

Contribution of CIMMYT Wheat Germplasm to Genetic Improvement of Grain Yield in Spring Wheat of Sichuan, Yunnan, Gansu, and Xinjiang Provinces

ZHANG Yong, LI Shi-Zhao, TUN Zhen-Lu, YANG Wen-Xiong, XU E-Xiong, XIA Xian-Chun, HE Zhong-Hu

Acta Agron Sin. 2011, 37(10):  1752-1762.  doi:10.3724/SP.J.1006.2011.01752

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Information on advances in wheat (Triticum aestivum L.) productivity is essential for genetic improvement on yield potential. Four yield potential trials with totally 59 leading cultivars from Sichuan, Yunnan, Gansu, and Xinjiang, China were conducted using a randomized complete block design with three replications under controlled environments in two successive cropping seasons from 2007 to 2009. The experimental sites were located in Chengdu in Sichuan province, Lijiang in Yunnan province, Wuwei in Gansu province, and Changji in Xinjiang province. Molecular markers were used to detect the presence of dwarfing genes and 1B/1R translocation. The results indicated that the annual genetic gain in yield in Sichuan, Yunnan, Gansu, and Xinjiang was 0.73%, 0.34%, 0.58%, and 1.43%, respectively. There was no obvious trend of yield component improvement for yield increase in Sichuan province; while reduced spikes per square meter and increased kernels per spike were the main factor for yield increase in Yunnan province; increased kernels per spike were the main factor for yield increase in Gansu province; and increased kernel weight of main spike and harvest index were the main factor for yield increase in Xinjiang province, together with the contribution from reduced plant height and earlier maturity. It also indicated that the dwarfing genes Rht-B1b and Rht-D1b were all from CIMMYT lines, and the significant progresses of genetic gain in yield in the four provinces were mainly due to the direct and indirect use of CIMMYT germplasm. Stripe rust resistance was the main contribution of CIMMYT germplasm in Sichuan and Yunnan; while CIMMYT germplasm contributed to high yield potential with high kernel number per spike, short plant height, and wide adaptability in Xinjiang and Gansu.

Construction and Analysis of Tobacco SSH Library Induced by Phytophthora parasitica var. nicotianae

SU Zhen-Gang, YANG Ai-Guo, SUN Yu-Ge, LUO Cheng-Gang, LIU Guan-Shan, ZHOU Jia, LI Yuan-Yuan, YANG Fan, ZHAO Bai-Yang, WANG Yuan-Yang

Acta Agron Sin. 2011, 37(10):  1763-1770.  doi:10.3724/SP.J.1006.2011.01763

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Black shank of tobacco is one of the major disease which harmful to tobacco in the world, the incompatible interaction between tobacco and Phytophthora parasitica var. nicotianae was studied to provide more information for integrated control. A cDNA-SSH library was established by suppression subtractive hybridization using roots and stems sampled at 0.5, 1, 3, 6, 10, and 16 d after inoculation of Gexin 3, a horizontal resistant cultivar to race 0 of Phytophthora parasitica var. nicotianae, and 960 positive clones were picked out. Among them, 240 positive clones were verified by Reverse Northern dot-blot. A total of 57 differentially expressed EST sequences were screened out, and 33 high quality non-redundant ESTs were obtained by cluster analyses of the ESTs sequencing.The results of BlastN showed that the resistant genes of tobacco mainly related to disease defense, photosynthesis, signal transduction, and energy metabolism. Further analysis of gene function indicated thatPR1b protein, cysteine proteinase, EF1-α, α-tubulin, cytochrome P450, putative spermine synthase, aquaporin, peroxisomal membrane protein,glycine for the elongation factor-1α may be involved in the process of the incompatible interaction between tobacco and Phytophthora parasitica var. nicotianae.

Function Analysis of the Gene OsASIE1 Responding to Abiotic Stresses in Rice

WU Hui-Min, HUANG Li-Yu, PAN Ya-Jiao, JIN Peng, FU Bin-Ying

Acta Agron Sin. 2011, 37(10):  1771-1778.  doi:10.3724/SP.J.1006.2011.01771

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AP2/EREBP transcription factors play an important role in plant development, hormone response, biotic and abiotic stress responses. We identified that OsASIE1, a member of EREBP subfamily of AP2/EREBP transcription factor family in rice, was involved in abiotic stress response. Expression of OsASIE1 wasinduced by drought and salt stresses, and over-expression of OsASIE1 in the transgenic rice plant could improve its tolerance to salt stress.Further electrophoresis mobility shift assay (EMSA) revealed that the AP2 domain of OsASIE1 protein could bind both DRE (dehydration-responsive element) and GCC box (ethylene response element, ERE) in vitro. All these results implicated that OsASIE1 might be involved in abiotic stress response by regulating the expression of downstream genes with DRE and GCC box binding.

Phenotypic Characterization and Genetic Mapping of an Increased Stigma Mutant in Rice (Oryza sativa L.)

ZHOU Meng-Jing, WEN Yong, LI Shuang-Cheng, LI Cheng-Bei, ZHANG Man-Hua, GAO Feng-Yan, WANG Ling-Xia, LI Ping

Acta Agron Sin. 2011, 37(10):  1779-1784.  doi:10.3724/SP.J.1006.2011.01771

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Floral organ development directly affects rice yield and quality. Here we report a rice floral mutant with increased stigmas, which was isolated from the progenies of the combination of C2/2480. Compared with the wild type rice, the mutant showed dwarf plant, small panicle and grain, curled flag leaf, narrow and opening spikelet, as well as later flowering. Most of florets were made up of normal lodicule, increased stigmas, more pistils, and fewer stamens. Segregation of wild type plants to mutant plants in three F₂ population were accorded with the ratio of 3:1, which indicated that the mutant is controlled by a single recessive gene. With SSR (Simple Sequence Repeat) markers screening in a total of 92 F₂ mutant individuals derived from the cross of ism/T116, the mutant gene was located between the molecular markers RM3183 and RM3827, at the distances of 2.2 cM and 12.0 cM, respectively, on chromosome 6, and co-segregated with RM11951, RM19953 and RM19961. ISM(t) is a new floral-organ identity gene located on chromosome 6 in rice.This result provided a foundation of map-based cloning and function analysis of ISM(t) gene.

Utilization Potential of the Temperate Maize Inbreds Integrated with Tropical Germplasm

CHEN Hong-Mei, WANG Yan-Fen, YAO Wen-Hua, LUO Li-Ming, LI Jia-Li, XU Chun-Xia, PAN Xin-Meng, GUO Hua-Chun

Acta Agron Sin. 2011, 37(10):  1785-1793.  doi:10.3724/SP.J.1006.2011.01785

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A diallel mating experiment was conducted among ten maize lines--five tropical, subtropical maize inbreds and five temperate maize inbreds developed by consecutive backcross and introducing tropical germplasm. Totally, ninety crosses were made based on Griffing method III. The objectives of this study were to evaluate (1) combining ability of the ten lines; (2) heterosis and heterotic performance of these crosses between the temperate lines integrated with tropical germplasm and the same tropical lines. Ninety crosses were evaluated in Kunming, Yunnan province in 2008 and 2009. One local elite hybrid Yunrui 6 was used in the trials as a check. The results showed that the inbreds integrated with tropical germplasm YML598 and YML58 had highly significant GCA effects for most traits, which should have high use potential in maize hybrid breeding programs. And it was found that combining ability for grain yield was closely related to combining ability for most of yield component factors, yield per plant had positive correlation with most of traits except anthesis silking interval and round tip. And it was showed that most of hybrids with relative heterosis H≥10% and highly significant SCA effects for yield per plant were the crosses between tropical & subtropical lines and temperate lines, which suggested that the five tropical & sub-tropical inbreds and five temperate inbreds still belonged to their previous heterotic group respectively, and their heterosis did not be changed. Thus, using tropical & subtropical lines as donor, backcrossing consecutively with temperate lines may be an effective way to improve the latter.

Analyzing Synchronization Process of Mitosis Cells in Wheat Root-tip with Flow Karyotype

GUO Dong-Wei, ZHANG Ren-He, LI Chun-Lian, CHEN Yao-Feng, MIN Dong-Gong, CHEN Ming, LI Lian-Cheng, XU Zhao-Shi, MA You-Zhi

Acta Agron Sin. 2011, 37(10):  1794-1800.  doi:10.3724/SP.J.1006.2011.01794

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Genomic sequencing of wheat can be simplified through constructing chromosome specific library. Synchronization of cells is propitious to high mitosis index (MI), which results in the accumulation of metaphase chromosomes and a successful flow sorting. In the present study, we used a double-blocked strategy in the synchronization treatment of wheat (Triticum aestivum L. cv. Chinese Spring) root-tip cells with 50 µmol L^-1 hydroxyurea (HU) and 100 µmol L^-1 trifluralin. The effects of treatments were evaluated by analyzing the dynamic proportions of cells at different stages of cell cycle. The optimal hours of treatments were 10 h for HU block, 7 h for recovery, and 4 h for trifluralin block. According to this synchronization scheme, the maximum MI was 70.1%. Additional ice water (0°C) depression was helpful for decreasing chromosome debris and rising resolution of the flow karyotype, but had no effect on the accumulation of metaphase chromosomes in root-tip cells.

Molecular Cloning and Expression Analysis of C₄ Phosphoenolpyruvate Carboxylase Gene from A. hypochondriacus L.

FENG Rui-Yun, BAI Yun-Feng, LI Beng, ZHANG Wei-Feng, WANG Yuan-Yuan, YANG Wu-De

Acta Agron Sin. 2011, 37(10):  1801-1808.  doi:10.3724/SP.J.1006.2011.01801

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Phosphoenolpyruvate carboxylase (PEPC) plays a crucial role in primarily fixing atmospheric CO₂ in C₄ and CAM plants. This paper aimed at cloning both cDNA and genomic DNA of PEPC gene from Amarnthus hypochondriacus in order to provide candidate genes for C₄ genetic engineering. The cDNA was cloned by RT-PCR, and the corresponding gDNA was cloned by LA-PCR. The sequence characteristics were analyzed using bioinformatics softwares including Blast, ClustalX (1.8), DNAMAN, PlantCARE. The gene expression pattern was analyzed by using semi-quantitative RT-PCR. The results indicated that the cDNA with the complete coding region was 2 895 bp in length which encoded 964 putative amino acids. The amino acid at site 774 was the serine that is an invariant residue in all C₄ phosphoenolpyruvate carboxylases regardless of their taxonomic. The corresponding gDNA was 6 785 bp in length which harbored ten exoned and nine introns. The longest intron was the first intron with 1 662 bp in length. A computer scan disclosed that the first intron harbored 15 light-induced elements, nine hormone-induced elements, 29 TAAT motifs and 72 TATA motifs.In comparisons of PEPC genes between different species the exons are usually conserved but the introns have often diverged in both nucleotide sequences and lengths. The GC ratios of exons are positively correlated with those of introns in PEPC genes from different species. And the GC ratios of PEPC gene in dicotyledon A. hypochondriacus, potato, A. thaliana and ice plant are lower than those in monocotyledon maize, rice and wheat. The semi-quantitative RT-PCR analysis revealed that the cloned PEPC gene was light-inducible leaf-specifically expressed and classified as C₄-type sub-family groups.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effect of Non-flooded Straw-mulching Cultivation on Grain Yield and Quality of Direct-seeding Rice

ZHANG Zi-Chang, LI Hong-Wei, WANG Hua-Meng, YUAN Chi-Min, WANG Zhi-Qin, LIU Li-Jun, YANG Jian-Chang

Acta Agron Sin. 2011, 37(10):  1809-1818.  doi:10.3724/SP.J.1006.2011.01809

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There aretwo problems in rice production in China: the one is the water shortage and another is labor shortage because of the climate change and economic development. Therefore, water-saving and labor-saving techniques should be developed. The direct-seeding is considered as a labor-saving while the non-flooded mulching cultivation as a water-saving practice. The aim of this study was to investigate if non-flooded straw mulching cultivation could maintain both grain yield and quality of direct-seeding rice. Two rice cultivars currently used in the production, Yangdao 6 (an indica) and Yangjing 4038 (a japonica), were field grown using a direct-seeding method, and three treatments, non-flooded wheat-straw-mulching (SM), non-flooded and no mulching (NM), and traditional flooding and no mulching (Control, TF), were imposed from 10 days after sowing to maturity. Compared with that under TF, grain yield showed some reduction under both SM and NM. The reduction in yield was 1.9–6.6% under SM, and 18.0–27.6% under NM. The difference in grain yield was not significant between SM and TF, and was significant between NM and TF. SM significantly improved head rice, gel consistency, albumin, glutelin and eating quality, and significantly reduced chalky kernels, chalkiness and prolamine content, and NM had the opposite effect.The results indicated that non-flooded wheat-straw-mulching could maintain a high grain yield and improved grain quality for direct-seeding rice. Greater leaf photosynthetic rate, root activity, and contents of indole-3-acetic acid and zeatin+zeatin riboside under such a practice contributed to a high grain yield and better quality, whereas NM significantly reduced these physiological parameters, and consequently reduced grain yield and quality.

Differences in Responding Sensitivity to Ethephon among Different Maize Genotypes

WEI Xiao-Die, ZHANG Meng-Cai, LI Shao-Hu, DUAN Liu-Sheng

Acta Agron Sin. 2011, 37(10):  1819-1827.  doi:10.3724/SP.J.1006.2011.01819

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Lodging is one of the key limiting factors causing serious yield decline in maize cultivation, the plant growth regulator ethephon and its complex formulation are applied to improve quality and lodging-resistance ability of stalks, which is an effective way to prevent stalk lodging. The responses in plant-type, physiological and biochemical characteristics of maize hybrid Nongda 108, Ludan 981 and their corresponding parents Xu 178, Huang-C, Qi 319, and lx9801 varieties, were studied in field condition, with 200 mg L^-1 ethephon foliage spray at jointing stage. The results showed that ethephon significantly inhibited the elongation of the first to sixth basal internodes for Nongda 108 and Ludan 981, the plant height and the ear height of Nongda 108 and Ludan 981 were significantly reduced. Ethephon remarkably increased the activities of phenylalanine ammonia lyase (PAL) and indole acetic acid oxidase (IAAO) and content of abscisic acid (ABA) in elongating internodes, and decreased contents of auxin (IAA) and gibberellin (GA₄). The genetic traits were analyzed, the plant height and the ear height of Xu 178, Huang-C, Qi 319, and lx9801 were significantly reduced after ethephon treating, and the length of basal internodes was shortened significantly. The PAL and IAAO activities in elongating internodes were significantly increased after ethephon treating. The endogenous IAA content of elongating internodes was significantly decreased, ABA content was significantly increased, but GA₄/ABA ratio was significantly decreased. It is indicated that the response differences to ethephon among different hybrids may be attributed to the different sensitivities of the parents lines, showing corresponding performance in plant height, ear height, PAL, IAAO activities and endogenous hormone levels.

Effects of NO on NO Contents and Anti-oxidative Enzymes in Cotton Leaf at Growth Stage

MENG Yan-Yan, FAN Shu-Li, SONG Mei-Zhen, LONG Chao-You, YU Shu-Xun

Acta Agron Sin. 2011, 37(10):  1828-1836.  doi:10.3724/SP.J.1006.2011.01828

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Under natural condition and spraying exogenous NO, cotton cultivars with different senescence traits were used to investigate changes in NO contents, anti-oxidative enzymes and related gene expression during the aging process of euphylla and cotyledons. The results indicated that, under field condition, the NO contents showed the highest level in the young leaf and declined gradually with the progression of leaf senescence. The NO content in presenescent cultivar decreased faster and was significantly lower than that of non-presenescent cultivar at the late stage of leaf senescence. Under laboratory condition, the NO content of cotyledons was the highest in young leaf and the lowest at late growth stage. After application of SNP solution, the NO content was significantly higher in the treatment group than that of control group during the whole period of cotyledon development. The activities of catalase (CAT) and ascorbate peroxidase (APX) and their genes expressions were comparatively lower at the seventh day and reached the highest level at the fourteenth day both in the control and treatment groups, then declined with leaf development; at the same stage, the activities of CAT and APX in treatment group were significantly higher than control group, especially at the late stage of cotyledons. The activity of peroxidase (POD) and its gene expression declined significantly by spraying exogenous SNP. Although exogenous NO could inhibit the activity of superoxide dismutase (SOD) at early stage of cotyledon development, the treatment group demonstrated greater SOD activity than that of control group in the process of leaf senescence. The responses of different types of SOD to NO varied, and the Cu/Zn SOD was the most sensitive isoforms, among which cCu/Zn SOD’s genes played a more potent role. The physiological and molecular mechanism underlying the delaying effect of NO on leaf senescence is thus revealed by fine coordination of the activity of oxidation and anti-oxidation systems (CAT, APX, POD, and SOD) in plant.

Precise Postponing Nitrogen Application and Its Mechanism in Rice

ZHANG Hong-Cheng, TUN Gui-Cheng, DAI Ji-Gen, HE Zhong-Xiang, HU Ke, GAO Hui, WEI Hai-Yan, LV Xiu-Chao, MO Jing-Jun, HUANG Yin-Zhong

Acta Agron Sin. 2011, 37(10):  1837-1851.  doi:10.3724/SP.J.1006.2011.01837

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Leaf ages of nitrogen application for high yield and apparent nitrogen recovery efficiency were specified through applying nitrogen fertilizer once in middle stage of growth and development using early-maturing and late japonica rice—Wuyunjing 7, Wuxiangjing 14, Changyou 1 as materials. Based on this, we studied precise postponing nitrogen application and its mechanism. Results showed that leaf ages of nitrogen application to high yield and apparent nitrogen recovery efficiency were 3rd leaf and fourth leaf from the top in early-maturing and late japonica rice. Using nitrogen in 3rd and 4th leaf from the top, made more panicles and spikelets per panicle, larger total spikelets and stable filled-grain percentage and 1000-grain weight, and lower max number of stems and tillers, higher ratio of productive tillers to total tillers, higher nitrogen accumulation, max LAI, LAD and dry matter weight in population growth and development. Yield with “PPM” (precise promoting in the middle phase) of nitrogen was significantly more than that of CK. Compared to CK, there were more significant apparent nitrogen recovery efficiency, physiological nitrogen use efficiency, agronomic nitrogen use efficiency and yield of ear nitrogen, but lower nitrogen requirement for 100 kg grain in “PPM” of nitrogen. Mechanism of high yield and apparent nitrogen recovery efficiency in “PPM” of nitrogne was that high ratio of productive tillers to total tillers and enough population panicles were formed through consolidating population panicles and controlling non productive tillering and low effective tillering; high grain-leaf ratio (filled grains per cm² leaf area, grain weight per cm² leaf area), enough quantity and good quality of dry matter in heading were obtained through forming large population spikeletes, high and appropriate LAI and fine canopy structure; intense source and smooth translocation, effective sink-filling alility were enlarged through enriching dry matter accumulation after heading and coordinating producton and translocation of dry matter from population stems and sheaths.

Nitrogen Accumulation and Distribution in Rapeseed (Brassica napus. L) with Different Nitrogen Utilization Efficiencies for Grain Production

ZUO Jing-Song, GE Yun-Long, LIU Rong, YAN Cui-Yan, TANG Yao, YANG Guang, LENG Suo-Hu

Acta Agron Sin. 2011, 37(10):  1852-1859.  doi:10.3724/SP.J.1006.2011.01852

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In this study, 98 conventional rapeseed (Brassica napus. L) varieties were grown with N₀ treatment (0 kg N ha^–1) and N₁ treatment (60 kg N ha^–1) in 2007–2008. Dry matter weight and content of nitrogen were tested at maturing stage. The rapeseed varieties were classified into six types based on their nitrogen use efficiency for grain production (NUEg) by the MinSSw method. The results showed that differences of NUEg in the varieties used in this study were significant. As NUEg increased, yield increased. The correlation analysis showed that NUEg was not significantly correlated with total amount nitrogen accumulation (r_N0= –0.0245,r_N1= –0.1131^**). NUEg had extremely significantly positive correlation with nitrogen distribution ratios in stems (r_N0= –0.5941^**, r_N1= –0.4141^**) and shells (r_N0= –0.6007^**, r_N1= –0.5374^**), but extremely significantly negative correlation with the amount of nitrogen in seeds (r_N0=0.7954^**, r_N1=0.7239^**). NUEg had extremely significantly positive correlation with total number of seeds also (r_N0=0.5945^**, r_N1=0.5412^**). NUEg and total amount of nitrogen accumulation influenced yield significantly. Cultivar breeding should be based on a certain total amount of nitrogen accumulation, and promote nitrogen to transport from vegetative organs to seeds, so as to achieve high yield and high nitrogen efficiency in rapeseed production.

High Photosynthetic Efficiency of Leaf Colour Mutant of Rice (Oryza sativa L.)

OU Li-Jun

Acta Agron Sin. 2011, 37(10):  1860-1867.  doi:10.3724/SP.J.1006.2011.01860

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Biao 810S is a yellow-green leaf mutant of the thermosensitive genic male sterile (TGMS) rice which has higher photosynthetic rate. The photosynthetic characteristics of Biao 810S were studied with the wild type TGMS line 810S as a control to clarify the physiological basis of high photosynthetic efficiency and provide a theoretical basis for further utilization. The photosynthetic pigment, photosynthetic rate, fluorescence parameters and activity of photosynthetic key enzyme were measured. The content of photosynthetic pigment in Biao 810S was approximately half of that in 810S. However, the net photosynthetic rate of Biao 810S was higher than that of 810S under high intensity light and Biao 810S had no obvious ‘Midday depression’ phenomenon. The stomatal conductance of Biao 810S was highly increased and the light quantum transformation efficiency was higher than that of 810S. The activity of ribulose -1,5-bisphosphate carboxylase (RuBPCase) in Biao 810S was 69.80% of that in 810S, but the activities of phosphoenolpyruvate carboxylase (PEPCase) and NADP-malic enzyme (NADP-ME) were 79.50% and 69.06% higher than those of 810S. The efficiency of light utilization in Biao 810S was enhanced by reduction of thermal dissipation and increase of electron transfer rate was generate sufficient assimilation power for the dark reactions. Consequently, the increased activities of PEPCase and stomatal conductance led to more effective fixation of CO₂, and the synergistic effect of light reactions and dark reactions contributed to the higher photosynthetic rate of Biao 810S.

Monitoring and Predicting of Maize Chilling Damage Based on Crop Growth Model in Northeast China

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

Acta Agron Sin. 2011, 37(10):  1868-1878.  doi:10.3724/SP.J.1006.2011.01868

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Although atmospheric temperature is obviously increased in northeast China with the global warming, regional maize chilling damage still occurs due to North extension of cultivation region of relative late-maturing varieties. Therefore, the research on monitoring and predicting maize chilling damage is still necessary. In this paper, we firstly constructed chilling damage indexes based on northeast China maize growth model (NEC_MaGM), and then developed the methods of monitoring and predicting maize chilling damage. The results are as follows: (1) In the eight individual chilling damage indicators selected from adverse weather conditions and the response of maize growth to low temperature, the second one (DC_Tas9, reduction of heat units during tasseling to September 31 compared with multi-year average.) and the first one (DN_Tas, the difference of tasseling stage between this year and multi-year average) had the best historical matching capability for chilling damage. The accuracy of chilling damage simulation based on DN_Tas and DC_Tas9 was 93.0% and 81.4%, respectively. (2) Based on formation mechanism of chilling damage, historical matching capability of every individual indicator and its independence, we constructed an integrated chilling damage index, which included the first, the second, the forth (DW_GrS, the loss of WSO suffered by low temperature in growing season compared with multi-year average) and the seventh individual indicators (DW_Fro, the loss of WSO suffered by first frost). (3) Chilling damage was monitored for every site by using NEC_MaGM and indicators, and then regional maize chilling was described by calculating the proportion of the site with chilling damage. On the base of integrated index, we defined that regional chilling damage should have more than 45% of maize chilling site. Thus, the accuracy and the skill score of maize chilling damage simulation were 93.6% and 84.2%, respectively. The result of independent samples test was consistent with actual situation. (4) Monitoring of chilling damage in the grid scale could be described more detailed spatial distribution. With the constantly updated live weather data, chilling dynamic monitoring could be achieved. The causes of chilling damage in the different regions were explored by using every individual indicator. The severity and spatial distribution of chilling damage simulations in the grid scale were fairly consistent with the literature. This method of monitoring chilling damage was favorable to business development of agricultural meteorological services. (5) According to weather data measured and predicted by regional climate models, combined with climate average data, regional maize chilling damage could be predicted by using NEC_MaGM. Case study showed that the method reflected to some extent the development and severity of chilling damage, but its accuracy was not only related with crop models, but also depended on simulation ability of regional climate model. The study could provide a scientific basis for the disaster prevention and mitigation.

Effect of Shade on Nitrogen Metabolism and Its Mechanism in Cotton Plant at Flowering and Boll-forming Stage

XU Sha, WANG You-Hua, ZHOU Chi-Guo, LV Feng-Juan, LIU Jing-Ran, MA Yi-Na, CHEN Ji

Acta Agron Sin. 2011, 37(10):  1879-1887.  doi:10.3724/SP.J.1006.2011.01879

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Cotton is an important economic crop in China and light is a major limiting factor to yield in cotton. The objective of the experiment was to clarify the effect of low light stress on nitrogen metabolism in cotton (Gossypium hirsutum L.) plant. Cotton cultivars (Sumian 15, Kemian 1) were grew in pots, and treated with three light densities (100%, 80%, 60% of natural light) at the flowering stage in 1st–2nd fruiting node on 6–8th fruiting branches. It was sampled four times with 15-day intervals from onset to bolls open. Cotton root vigor, root absorption and activities of the nitrate reductase, glutamine synthase, glutamate synthase and glutamate dehydrogenase were analyzed. The results showed that with increase of the shading level, root vigor and root absorption decreased seriously. Both in root and function leaf, activities of the nitrogen metabolic enzymes, such as NR, GS, GOGAT were seriously inhibited at the 15th days of shade. The activities of nitrate reductase (NR), glutamine synthase (GS), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH) decreased by 25.1%, 53.2%, 39.1%, 25.5% in root, while 50.3%, 24.0%, 30.4%, 18.9% in function leaf. The descending of nitrogen absorption in cotton root resulted from the drop of GS/GOGAT activity firstly and the drop of NR activity secondly, but the decreasing of nitrogen metabolic ability in functional leaf induced from the drop of NR activity firstly and the drop of GS/GOGAT activity secondly. Low light could repress root vigor and root absorption. The activities of NR, GS/GOGAT were also suppressed, which resulted decrease of amino acid content, soluble protein content and nitrogen accumulation both in root and function leaf with the increasing of the shading level. The yield of cotton plant also decreased with the shading and the boll number was the most sensitive to shade.

Effects of Nitrogen Fertilization on Seed-setting Characteristics of Spike and Grain Yield in Winter Wheat under Waterlogging at Booting Stage

WU Wen-Meng, LI Jin-Cai, CHEN Hong-Jian, WEI Feng-Zhen, WANG Shi-Ji

Acta Agron Sin. 2011, 37(10):  1888-1896.  doi:10.3724/SP.J.1006.2011.01888

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Waterlogging has great influence on yield reduction in winter wheat production in some areas of China. Nitrogen (N) application is believed to be able to improve dry matter translocation in wheat, as a result to increase final yield. In a field experiment across two growing seasons, we used winter wheat cultivar “Wanmai 54” to investigate the effect of waterlogging at booting stage and N fertilizing strategy on number and weight of grain at different spikelet positions and grain positions. Under both waterlogging and control (normal watering) conditions, we implemented four N application treatments with different N application ratios (total N amount of 240 kg ha^{-1 in all treatments) at land preparation, jointing, and booting stages (10:0:0 for N1, 7:3:0 for N2, 5:5:0 for N3, and 3:5:2 for N4). The results showed that seed-setting characteristics of main stem were superior to tiller spike. In the N1 treatment, the sterile spikelet per spike was significantly increased, and the grain number per spike was significantly decreased. Compared with N4 treatment, sterile spikelet per spike of N1 treatment increased by 25.5% and 29.8% in 2008–2009 and 2009–2010 growing seasons, respectively. The grain number per spike of N1 treatment decreased by 5.7%. Waterlogging had greater effect on the tiller spike than the main stem spike. Waterlogging at booting stage significantly increased sterile spikelet per spike by 10.6% and 4.5%, and the grain number per spike decreased by 2.8% and 1.4% in the two growing seasons, especially for spike with four grains on main stem and three grains per spike of tiller spike, the grain weight in the third and the fourth grain positions, the contribution rate of the third and the fourth grain weights to the grain weight per spike. With the delay of N fertilization, spikelet per spike, single weight per spike increased significantly, the sterile spikelet per spike decreased compared to the prior N fertilization treatments. Postponed N fertilization could compensate the decrease of spike with three and four grains and increase the grain weight in third and the fourth grain positions under waterlogged environment at booting stage, increase the contribution rate of the third and the fourth grains weight to the grain weight per spike. Therefore, with the postponed N fertilization, grain yield and spikelet grain number and grain weight at different spikelet of wheat were enhanced. Results indicate that postponed N fertilization alleviates the effect of waterlogging at booting stage on the seed-setting characterisitics of spike and single grain weight.}

RESEARCH NOTES

Utilization of Tissue Specific Expressing Promoter RSS1P in TiERF1 Transgenic Wheat

LI Zhao, PENG Hong-Chao, DU Li-Pu, ZHOU Miao-Beng, CA Shi-Bin, XU Hui-Jun, LI Shi-Shen, ZHANG Ceng-Yan

Acta Agron Sin. 2011, 37(10):  1897-1903.  doi:10.3724/SP.J.1006.2011.01897

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A sucrose synthase-1 promoter (RSS1P) was cloned from rice leaf, and subcloned in-fused with 5′-terminate of the gene of ethylene responsive factor of Thinopyrum intermedium (TiERF1) to form the RSS1P::TiERF1 expressing cassette. The expressing cassette replaced the Ubi::bar gene expression cassette of pAHC20 to produce the phloem-specific expressing vector pA20-RSS1P::TiERF1. The selective mark bar was deleted in the pA20-RSS1P::TiERF1 vector, which is safe for the ecosystem. Using the method of bombardment, the vector DNAs of pA20-RSS1P::TiERF1 andpAHC20 with bar gene were co-transformed to young embryo callus of wheat cultivar Yangmai 12. The RSS1P::TiERF1 transgenic plants in T₀ and T₁ generations were subjected to PCR, PCR-Southern, RT-PCR, and Q-RT-PCR analyses, and Rhizoctonia cerealis resistance tests. The molecular detection results showed that the transgene RSS1P::TiERF1 was introduced into Yangmai 12 and was inheritable. In the RSS1P::TiERF1 transgenic wheat plants, expression of TiERF1 was detected in root, stem, and leaf except seed. The highest expression level was observed in root. Compared to the untransformated Yangmai 12, resistance to R. cerealis in the RSS1P::TiERF1 transgenic wheat plants was obviously improved, which was similar to that in the Ubi::TiERF1 transgenic wheat plants. The agronomic traits of RSS1P::TiERF1 transgenic plants had no obvious changes compared to untransformated Yangmai 12. These results suggest that RSS1P promoter is feasible to be used for developing new transgenic wheat germplasm.

Isolation and Characterization of an Embryo-specific Promoter OsESP1 from Rice

FANG Xiao-Liang, LIU Wei, AN Jing, WANG Qiang-Guo

Acta Agron Sin. 2011, 37(10):  1904-1909.  doi:10.3724/SP.J.1006.2011.01904

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A pair of specific primers were designed according to the 5′ upstream regulatory sequence of rice gene OsESG, anda 1.4 kb fragement named OsESP1was amplified using rice (Oryza sativa L. cv. Zhonghua 11) genomic DNA as template by PCR. OsESP1 was further fused with GUS reporter gene and transformed into rice callus through Agrobacterium-mediated transformation. GUS activities in various tissues of transformed plants were examined and the GUS activity was detected only in rice embryo, indicating theOsESP1 is an embryo-specific promoter.

Effects of Controlled-release N Fertilizer on Fiber Quality, Yield and N Use Efficiency

LI Xue-Gang, SONG Xian-Liang, SUN Hua-Zhen, CHEN Er-Ying, ZHANG Mei-Ling, ZHAO Qiang-Long

Acta Agron Sin. 2011, 37(10):  1910-1915.  doi:10.3724/SP.J.1006.2011.01910

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e seed cotton yield and lint cotton yield of 100% PCU treatment were increased by 6.2% and 6.4%, and those of PFP_N and AE_N were significantly enhanced. For 100% CRBBF treatment, fiber length was increased on 21 to 31 Aug., fiber strength was enhanced on 21 to 31 July and 21 to 31 Aug., fiber micronaire was augmented on 1 to 31 Aug., and fiber maturity was improved on 1 to 20 Aug.. The seed cotton yield and lint cotton yield of CRBBF treatment were increased by 5.0% and 4.3%, respectively, and those of PFP_N and AE_N were also significantly enhanced. For 50% PU+50% PCU treatment, fiber strength was enhanced on 21 to 31 July, micronaire was augmented on 11 to 20 Aug., fiber maturity was improved on 11 to 20 Aug. But there were no obvious differences on yield and nitrogen use efficiency between 50% PU+50% PCU treatment and CK₂. In conclusion, 100% PCU treatment has the most obvious effect on yield and nitrogen use efficiency, while 100% CRBBF treatment could be better to improve fiber quality.