Acta Agronomica Sinica

Table of Content

12 November 2010, Volume 36 Issue 11

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REVIEW

Optimal Use of Biplots in Analysis of Multi-Location Variety Test Data

YAN Wei-Kai

Acta Agron Sin. 2010, 36(11): 1805-1819. doi:10.3724/SP.J.1006.2010.01805

Abstract ( 4107 )

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Biplot analysis has been increasingly used in visual analysis of genotype-by-environment data and other types of two-way data. While many plant breeders and agricultural researchers are enthusiastic about the capacity of biplot analysis in helping them to understand their research data, some statisticians consider the use of biplots as a sidetrack to genotype-by-environment interaction analyses. Confusion also exists among statisticians on what is or is not a biplot. Admittedly, some users of biplot analysis are not always clear on how to select a proper type of biplot for a particular research objective and how to interpret a biplot correctly, accurately, and adequately. Some criticisms of biplot analysis may arise from incomplete understanding of the practitioners’ research problems as well as of the biplot methodology. In this review, I summarize the experiences and understanding in biplot analysis of genotype-by-environment data achieved during the last decade and discuss the following issues: (1) how to choose a proper biplot; (2) how to choose a proper GGE (genotype + genotype-by-environment interaction) biplot; (3) how to use the key functions of a GGE biplot for genotype evaluation, test-environment evaluation, and mega-environment delineation; (4) how to judge the adequacy of a 2-D biplot; and (5) how to test the statistical significance of a biplot pattern.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Analysis of Genetic Structure and Genetic Relationships of Partial Maize Inbred Lines in China

TUN Cheng-Lai, ZHANG Qian-Qian, DONG Bing-Xue, ZHANG Chun-Qing

Acta Agron Sin. 2010, 36(11): 1820-1831. doi:10.3724/SP.J.1006.2010.01820

Abstract ( 2755 )

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Knowledge about the population structure and relationships within and among maize inbred lines was important to improvement and utilization of maize inbred line. Distance-based cluster and model-based cluster methods were used to analyze the genetic structure and relationship of 97 maize inbred lines used in China with 112 microsatellite (simple sequence repeat, SSR) markers, evenly distributed over 10 chromosomes. Results showed that model-based cluster method was more suitable for maize inbred line clustering than distance-based cluster method, because the former could define the group of inbred lines more effectively than the latter. All inbred lines were grouped into four groups by model-based cluster method: Reid, Lüda red cob (LRC), PB and Tangsipingtou (SPT). According to the result of genetic structure component (Q-value), numerous inbred lines in each group were overlapped in genetic component with the other groups. Reid group kept minimum Nei’s genetic distance with LRC group, had most distant genetic relationship with SPT group. The results of genetic relationships among groups indicated that the four groups could be simplified into three (A: Reid, LRC; B: PB; C: SPT) or two (A: Reid, LRC, PB; B: SPT) potential heterotic groups. The defined population and the genetic component analysis of inbred lines provided the basis for improving the efficiency of hybrid breeding.

QTL Analysis for Yield Components and Kernel-Related Traits in Maize under Different Water Regimes

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

Acta Agron Sin. 2010, 36(11): 1832-1842. doi:10.3724/SP.J.1006.2010.01832

Abstract ( 2502 )

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Maize yield and yield-related traits are seriously affected by water stress. Therefore, detecting quantitative trait locus (QTL) for yield components and kernel-related traits, analyzing the stability of QTLs and exploiting constitutive QTLs under different water regimes are of great importance in marker-assisted breeding for drought tolerance in maize. In this study two F_2:3populations derived from Qi319×Huangzaosi (Q/H) and Ye478×Huangzaosi (Y/H) were used to investigate the genetic basis of yield components and kernel-related traits under different water regimes in Xinjiang (including well-water and water-stress environments) by stepwise joint QTL mapping method. The results showed that above 70% of the QTLs for yield components and kernel-related traits expressed stably under the same water regime across the two years. The QTLs detected in water-stress environments were less stable than those in well-water environments across the two years in Xinjiang. The joint analysis combining data of all environments indicated that the stability of the QTLs for all traits decreased, but above 60% of them still expressed stably. A total of 11 constitutive QTLs (with contribution rate more than10% in at least one environment, detected in more than two environments based on single environment analysis) distributed on bin1.10, 2.00, 4.09, 7.02, 9.02, 10.04 and 10.07 were detected in the two populations, and all of them except bin10.04 were stable across all environments. Consequently, most of the QTLs for yield components and kernel-related traits stably expressed under the same water regime across different years, and even under different water regimes in Xinjiang. These constitutive QTLs may provide references for molecular breeding and further basic studies.

SSR Analysis of Genetic Diversity and the Temporal Trends of Major Commercial Inbred Indica Rice Cultivars in South China in 1949–2005

LIU Chuan-Guang, ZHANG Gui-Quan

Acta Agron Sin. 2010, 36(11): 1843-1852. doi:10.3724/SP.J.1006.2010.01843

Abstract ( 2284 )

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Three hundred SSR makers distributing evenly on the whole rice genome wereused to assess the genetic diversity among 95 major commercial inbred indica rice cultivars in South China in 1949–2005. Of the 300 SSR loci, 236 loci were polymorphic. A total of 776 alleles were detected at the 236 polymorphic loci. The mean number of alleles per locus was 3.29 with a range from 2 to 12. Two hundred and six SSR loci with 2 to 4 alleles accounted for 87.3% of all the 236 polymorphic loci. The average polymorphism information content (PIC) value was 0.42 with a range from 0.041 to 0.790. Among the 12 chromosomes, chromosome 10 showed the greatest values in mean allele number and PIC value, but chromosome 5 showed the lowest values. In six investigated decades, the number of detected alleles per locus increased from 1950s to 1970s, and then decreased after 1970s. Analysis of molecular variance (AMOVA) indicated that the genetic variation among the six decades was significant (P＜0.001)，though it just accounted for 3.77% of the total genetic variation. Genetic distance (GD) among cultivars gradually decreased from 1950s to 2000s. Clustering analysis with COMPLETE method based on genetic similarity coefficients (GS) showed that all the cultivars could be separated into five clusters with GS value 0.685. The clustering result indicated that the genetic improvement of inbred rice cultivars was just based on several core parents in different decades. It could be concluded that the genetic diversity of indica rice cultivars in South China is narrow and has been decreasing after 1970s, therefore there’s a need for incorporating new variability into the existent rice germplasm for broadening the genetic basis of cultivars.

Phylogenetic Relationships of Sugarcane Related Genera and Species Based on ITS Sequences of Nuclear Ribosomal DNA

LIU Xin-Long, SU Huo-Sheng, MA Li, LU Xin, YING Xiong-Mei, CAI Jing, FAN Yuan-Hong

Acta Agron Sin. 2010, 36(11): 1853-1863. doi:10.3724/SP.J.1006.2010.01853

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Sugarcane related genera and species are important germplasm resources for sugarcane breeding and germplasm innovation. To effectively collect these wild resources and utilize them, ITS (Internal Transcribed Spacer) sequence of 120 accessions which belong to eight genera and thirty seven species were used to analyze their genetic relationships and construct phylogentic relationships with P. purpureum as an outgroup. The results showed the sequence lengths of ITS1, ITS2 and 5.8sDNA of all accessions were 204–208 bp, 215–220 bp, and 164 bp respectively, and their variable sites were 91, 93, and 18, the informative sites were 70, 68, and 9, the GC content was 60.4%–69.1%, 66.1%–73.4% and 54.1%–58.0%. According to the ratio of the variable sites and informative sites to all sites, ITS sequence was richer in variances than 5.8sDNA sequence, and the variances of ITS1 sequence were richer than those of ITS2’s. The genetic distance analysis between sugarcane related genera and species indicated that Miscanthus and Triarrhena were the closest to Saccharum, and the closer ones were Erianthus and Narenga, so the species from these genera should be more considered on collecting sugarcane wild resources in the future; Microstegium, Spodiopogon and Imperata represented farther relationships with Saccharum. The sugarcane related genera and species were separated into ten groups according to the phylogenetic tree of neighbor-joining and maximum parsimony. According to their phylogenetic relationships, E. arundinaceus should be separated from Saccharum and clastified as Erianthus species; Triarrhena shoud be included in Miscanthus; the two species of Narenga did not remain in the same group, but N. porphyrocoma and E. rockii were clustered into the same group, and N. fallax did not belong to any groups, so further researches are needed in identifying the two species. These species from Erianthus and Miscanthus were put in different groups, indicating the very complex genetic relationships within Erianthus and Miscanthus, their species possess big genetic differences. Four samples were found error in classifying species, so the application of their ITS sequences should be avoided.

Frequency of ahFAD2A Alleles and Its Association with Oleic Acid Content in the Peanut Mini Core Collection from China

LEI Yong, JIANG Hui-Fang, WEN Ai-Gen, HUANG Jia-Quan, YAN Li-Yang, LIAO Bo-Shou

Acta Agron Sin. 2010, 36(11): 1864-1869. doi:10.3724/SP.J.1006.2010.01864

Abstract ( 2563 )

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Oleic acid content of cultivated peanut (Arachis hypogaea L.) seeds is controlled by the activity of oleoyl-PC desaturase, encoded by two homologous genes (ahFAD2A and ahFAD2B), high oleic acid content results from the mutation of ahFAD2A and ahFAD2B, simultaneously. Two alleles of the ahFAD2A (wild type ahFAD2A-wt and mutation type ahFAD2A-m) exist in the normal oleic accessions, whereas only the ahFAD2A-m allele exists in the high oleic accessions. The ahFAD2A-m is a spontaneous mutation type of ahFAD2A-wt (G-to-A at site 448 bp resulting in a D to N at 150 amino acid position), which results in a dysfunctional desaturase. A specific PCR primer pair for the ahFAD2A amplification was developed in this study. According to the sequencing result of PCR production of the mutant and wild-type ahFAD2A alleles, mutant allele (ahFAD2A-m) accounted for 53.1% of the accessions in the mini-core collection from China, which was frequently found in subspecies hypogaea accessions but absent from subspecies fastigiata accessions; the highly positive correlation between the ahFAD2A-m and the higher oleic acid content was observed. A new SNP was found at the 417 bp (T/C) in the open reading frame (ORF), which did not result in the amino acid substitution, and was found no correlation between the SNP of 417 bp and the oleic content. These results will be helpful for the breeders to select the parent material in the peanut high oleic acid breeding program.

Precision Evaluation of the Rice Variety Regional Trials in Northern China

WANG Ji, LIAO Qin, HU Xiao-Jun, WAN Jian-Min

Acta Agron Sin. 2010, 36(11): 1870-1876. doi:10.3724/SP.J.1006.2010.01870

Abstract ( 2545 )

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Crop variety regional trial is the basis of variety registration. The precision of regional trial directly influences the merits of approved varieties. According to new national certification standards, new rice varieties should yield more than 3% compared with the control, requiring much higher precision of the experiments. Since 1999, the national rice regional trials in northern China have been implemented for 10 years. It is extremely important for the variety approval committee to known that whether or not the experiments precision can reach the national registration requirements. Based on the data from rice variety regional trials in northern China from 1999 to 2008, we analyzed the experiment error precision (EP) and variety comparison precision (VCP) at two experiment levels. The results was as follows: (1)The average coefficient of variation (CV) and relative LSD (RLSD) in one-location-one-year experiments were 4.3% and 7.4% respectively, indicating the trials were well controlled. Both EP and VCP in one-location-one-year experiments were desirable. (2)The average CV and RLSD in most of multi-location-one-year experiments were lower than 5% and 3% respectively. The EP and VCP in multi-location-one-year experiments were desirable and met the requirements of the State Variety Approval. (3) Under the existing design of experiments，reducing experimental errors in the trials is the main way to improve the accuracy of one-location-one-year experiment. In addition to reducing experimental errors in the trials, the appropriate increase in the number of experiment sites is also a very effective choice to improve the accuracy of multi-location-one-year experiments.

Effects of Anti-Sense Thioredoxin s on Grain Yield and Quality Properties in Two Wheat Cultivars with Different Quality Types

REN Jiang-Ping, WANG Na, WANG Xin-Guo, LI Yong-Chun, NIU Hong-Bin, WANG Xiang, YIN Jun

Acta Agron Sin. 2010, 36(11): 1877-1882. doi:10.3724/SP.J.1006.2010.01877

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Thioredoxin h (Trxh) is a small protein catalyzing thiol-disulfide interchange, which is involved in many processes, such as activation or deactivation of enzymes and enzyme inhibition and germination. Wheat pre-harvest sprouting is caused by a series of hydrolyses, in which α-amylase plays a key role. The anti-trxs gene has been transferred into wheat (Triticum aestivum L.) cultivars “Yumai 18” and “Yumai 34” since 2003 to decrease Trxhreductive capability and α-amylase activity in wheat seed. From the T₄ generations, two transgenic lines, TY18 and TY34 were obtained. To investigate the effects of anti-sense thioredoxin s on grain yield and quality properties, TY18 and TY34 were tested in field experiments in 2007–2009 growing seasons with comparisons to their cultivars Yumai 18 (weak gluten) and Yumai 34 (strong gluten ). The result showed that the grain yield and quality properties of both lines were greatly affected. Compared with the wild controls, grain number per spike, grain yield and the starch quality in seeds of the transgenic lines were significantly promoted. The total starch content, amylopectin content, peak viscosity, trough viscosity, and final viscosity were significantly increased in transgenic lines, and the ratio amylase-to-amylopectin reduced, accordingly. The effects of transferring gene on protein quality were different in the two cultivars. The contents of total protein, albumin, globulin, and glutelin decreased significantly and the contents of gliadin increased significantly in the two transgenic lines of TY18. The development time and stability time of flour decreased significantly. However, these protein quality indexes had no significant differences between transgenic lines and controls, except contents of albumin, gliadin, and glutelin, which were decreased in transgenic lines TY34. Therefore, the anti-trxs gene transferred into wheat improved the starch quality of both wheat cultivars and the braking quality of weak-gluten cultivar.

Differential Expression of Genes in Gibberellin-Induced stalk elongation of Sugarcane Analyzed with cDNA-ScoT

WU Jian-Ming, LI Yang-Rui, WANG Ai-Qin, YANG Liu, YANG Li-Tao

Acta Agron Sin. 2010, 36(11): 1883-1890. doi:10.3724/SP.J.1006.2010.01883

Abstract ( 2422 )

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The present study was conducted to investigate the molecular mechanisms of gibberellin-induced stalk internodes elongation in sugarcane. Using sugarcane variety ROC22, the plant leaves were treated with spraying gibberellic acid (GA₃) at 200 mg L^–1 at early elongation stage, and spraying water as a control. Samples of young stalks were taken and the differentially expressed genes were analyzed with cDNA-SCoT technique. The results showed that 30 fragments of differentially expressed genes were obtained by screening 700 cDNA fragments with 46 single primers. The expressions of 18 genes were up-regulated, and 12 genes down-regulated by GA₃ induction, and the sequences of 16 TDFs showed high similarity to the registered genes in the NCBI database. These genes were divided into six categories by functional analysis, including energy and metabolism-related genes (accounting for 20.0%), unknown functional proteins (accounting for 20.0%), unknown genes (accounting for 46.7%), signal transduction-related genes (accounting for 6.7%), transcription factor-related genes (accounting for 3.3%), and cell apoptosis (accounting for 3.3%). This suggested that the differential expression of genes in the stalks can be analyzed with SCoT technique, and some fragments may be related to the stalk elongation of surgarcane.

Analysis of Up and Down Regulation Genes and Relative Pathway during Cotton Fiber Elongation

LENG Xue, GIA Yin-Hua, DU Xiong-Ming

Acta Agron Sin. 2010, 36(11): 1891-1901. doi:10.3724/SP.J.1006.2010.01891

Abstract ( 2333 )

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The fiber development is a crucial factor, influencing cotton yield and quality. The elongation period of fiber development is the key time to determine the fiber’s final length. The mechanism of fiber elongation is not known clearly now. We hope to find some information about it by using wild type and mutant microarray. It is an effective method to studying relevant genes of fiber development by comparing mutants and wild-type gene expression profiles. Cotton fiber formed by single-celled trichomes is the perfect material for studying cell elongation mechanism. Ligon lintless (Li₁) is a dominant mutant of upland cotton (Gossypium hirsutum L.) and its fiber is extremely short on mature seed, about 4–6 mm in length, but the wild type (li) is normal for plant and fibers. Recently, we constructed a cDNA microarray used the ovule total RNAs of the mutant and its wild-type. The results showed that many genes expressed up- (or down-) regulated between the mutant and wild type from –1 to +7 DPA (day post anthesis), and two genes (XET, CIPK)were validated by RT-PCR and qRT-PCR analysis. These genes were analyzed via the gene ontology and pathway with Molecule Annotation System (MAS) developed by Capitalbio Co, indicating that these differential expressed genes influenced some metabolism pathways including fatty acid metabolism, glycerolipid metabolism, reductive carboxylate cycle et al. The abnormal expression of these genes in the mutant Li₁maybe result in the change of the fatty acids and fat content, and further influence the fiber development.

Analysis of Genetic Diversity of Allotetraploid Cotton Based on SSR

GAO Wei, LIU Fang, LI Shao-Hui, WANG Chun-Ying, ZHANG Xiang-Di, WANG Yu-Hong, WANG Kun-Bo

Acta Agron Sin. 2010, 36(11): 1902-1909. doi:10.3724/SP.J.1006.2010.01902

Abstract ( 2334 )

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There are five allotetraploid cotton species including two cultivated varieties, G. hirsutum and G. barbadense, and three wild species, G. darwinii watt, G. mustelinum Miers ex Watt and G. tomentosum. Wild cotton contains not only wild species but also wild types of cultivated varieties, such as G. hirsutum L. races. Research on genetic diversity relationships among cultivated and wild cotton species is necessary for better understanding of cotton evolution and good use of wild resources. The aim of this study was to evaluate the genetic diversity of five allotetraploid cotton species and 42 wild types of upland cotton using SSR markers. A total of 95 from 1050 pairs of SSR primers were used to amplify the 60 accessions of germplasm, which could produce steady and clear polymorphic bands. Six hundred and sixty DNA fragments were scored among all materials, 584 polymorphic bands were obtained, accounting for 88.5% of the total bands. The allele number (NA) per SSR locus was 2–12, with the average of 6.1. UPGMA Cluster analysis based on SSR data showed that the genetic similarity (GS) coefficient among 42 accessions of germplasm ranged from 0.306 to 1.000, the mean genetic similarity (GS) coefficient was 0.493. For 95 primers, the polymorphism information content (PIC) was from 0.278 to 0.905. The Shannon-Weaver diversity index (H¢) ranged from 0.451 to 2.451, and effective number of alleles (Ne) varied from 1.385 to 10.490. The results showed that there is a wide genetic variation in wild types of upland cotton and allotetraploid cotton tested by SSR markers. The genetic relationship is nearest between upland cotton and G. hirsutum var. latifolium, very close Gossypium barbadense L. and G. darwinii watt, G. mustelinum Miers ex Watt and G. tomentosum L. Nuttall ex Seeman a bit close and farthest between upland cotton and others.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Quality Performance and Stability of Main Wheat Cultivars in Sichuan Province

TANG Yong-Lu, WU Yuan-Qi, ZHU Hua-Zhong, LI Chao-Su, LI Sheng-Rong, ZHENG Chuan-Gang, YUAN Ji-Chao, YU Xiu-Fang

Acta Agron Sin. 2010, 36(11): 1910-1920. doi:10.3724/SP.J.1006.2010.01910

Abstract ( 2151 )

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Southwest region is one of the most important wheat (Triticum aestivum L.) production area in China, of which Sichuan Province has the largest planting area of wheat. It is crucial to understand the quality potential and stability of major commercial cultivars and provide guidance for wheat production in Sichuan Province. Seven representative cultivars were planted in five ecological sites of Sichuan under two nitrogen application levels from 2006–2008, and eight quality traits and noodle- and bread-making scores were determined. Three-year averaged test weight, grain protein content, wet gluten content, Zeleny sedimentation, falling number, flour water abstraction, dough developing time, stability time, noodle score of dry white Chinese noodle, and bread score were 777 g L^-1, 12.3%, 25.1%, 32.9 mL, 326 s, 56.5%, 3.0 min, 4.5 min, 78.5, and 62.2, respectively. In a combined analysis of variance, effects of genotype, environment, and their interaction were significant for almost all traits tested. For test weight, Zeleny sedimentation, falling number, flour water abstraction, and noodle score of dry white Chinese noodle, the influences from year were greatly larger than those from location; whereas, for protein content, wet gluten content, dough developing time, stability time, and bread score, the influences from location were larger than those from year. Increasing nitrogen application significantly improved most quality traits and raised bread score, but had no influence on noodle score. Stability analysis revealed that Chuanmai 39 was stable for bread quality with the highest bread score value, while Chuanmai 37 was stable for most quality traits with the highest noodle score. This result indicates that Chuanmai 39 and Chuanmai 37 can be favorably used in wheat quality improvement in Sichuan Province.

Characteristics of Dry Matter Production and Accumulation and Super-High Yield of Japonica Super Rice in South China

WU Gui-Cheng, ZHANG Hong-Cheng, DAI Qi-Gen, HE Zhong-Yang, HU Ke, GAO Hui, WEI Hai-Yan, SHA An-Qin, XU Zong-Jin, QIAN Zong-Hua, SUN Ju-Ying

Acta Agron Sin. 2010, 36(11): 1921-1930. doi:10.3724/SP.J.1006.2010.01921

Abstract ( 2106 )

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The relationship between dry matter production and yield, dynamics of dry matter accumulation and output and translocation in middle and last stages of three types of populations (High Yield: 8.25–9.75 t ha^-1; Higher Yield: 9.75-11.25 t ha^-1; Super High Yield:＞11.25 t ha^-1) in four japonica super rice (Wujing 15, Huaidao 9, Xudao 3 and Changyou 1) were analyzed. The results showed that yield was significantly positively correlated with weight of dry matter at maturity and the dry matter accumulation from heading to maturity, there were parabolic relationships between yield and weight of dry matter at heading in high yield, higher yield and super-high yield populations. Weight of dry matter from jointing to heading was significantly positively correlated with yield from high yield population to higher yield population and from higher yield population to super-high yield population. Super-high yield population had more biomass at maturity than higher yield and high yield populations, and the harvest index was not significantly higher than that of higher yield population, but was significantly higher than that of high yield population. Weight of dry matter, LAI in heading, rate of leaf area of productive tillers, rate of leaf area from flag leaf to 3rd leaf, spikelets of population and spikelets per square centimeter leaf area in middle stage (from jointing to heading) were significantly higher than these of higher yield and high yield populations. Leaf area decreasing per day of super-high yield population from heading to maturity was significantly less than that of higher yield and high yield populations. Leaf area duration, crop growth rate, net assimilation rate, biomass and grain-leaf ratio (filled grains per square centimeter leaf area, grain weight per square centimeter leaf area) from heading to maturity were significantly higher than these of higher yield and high yield populations. Output and translocation of dry matter in super-high yield population from heading to milky stages were significantly higher than these of higher yield and high yield populations, while these from heading to maturity were significantly lower than these of higher yield and high yield populations. Weight per stem and sheath and total filling in maturity of super-high yield population were significantly higher than these of higher yield and high yield populations.

Effects of Seed Priming on Germination and Seedling Growth of Rice under Water Stress

SUN Yan-Yan, SUN Yong-Jian, WANG Meng-Tian, LI Xu-Yi, GUO Xiang, HU Rong, MA Jun

Acta Agron Sin. 2010, 36(11): 1931-1940. doi:10.3724/SP.J.1006.2010.01931

Abstract ( 2435 )

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Seeds of four different rice genotypes, Gangyou 527, Yangdao 6, Zhonghan 3 and Nongken 57, were treated with two priming method, H₂O and different concentrations of polyethylene glycol (PEG). Nonprimed or primed seeds were germinated under different water stress. The contents of proline, soluble protein (SP), total soluble sugars (SS), malonicdialdehyde (MDA), phenylalanine ammonia lyase (PAL), superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) in seeds or stressed seedlings, and seed germination and rice seedling characteristics were determined. The results showed that significantly higher levels of proline and SP and lower levels of SS and the content of MDA in primed seeds were observed as compared with control (nonprimed seeds). Priming accelerated the process of glucose metabolism, improved the activities of PAL, SOD, CAT and POD in stressed different genotypic rice seeds, moreover, priming effects was relatively significant. Rice seeds could be initiated significantly better by the priming of proper PEG concentration than hydropriming. The results showed that the best priming conditions was 20% PEG for hybrid indica rice seeds, and 10%–15% PEG for conventional japonica rice seeds. Normal germination of rice seeds it was inhibited when PEG content was beyond the threshold. Response of hydroprimed seeds or PEG primed seeds on seedlings growth of different genotypic rice under different water stresses. Showed that the proper water stress could activate material metabolism, promote rice seeds germination, and significantly increase kinds of physiological index of seedlings in different genotypes of rice, such as morphological index and protective enzymes after the treatment of proper PEG content, But it went against and serious water stress to inhibited germination..It showed that although seed priming treatment could improve activity of rice seedlings, the coordination ability to external germinating environment by self-regulation was limited. It also indicated that indica rice had greater PEG tolerance than conventional japonica rice, but better priming effects were observed in hybrid indica rice.

Systemic Regulation of Structure and Photosynthetic Characteristics in Developing Leaves in Sorghum Seedlings under Salt Stress

WANG Xin, LI Zhi-Jiang, GU Wei-Ban, SHI Lei, TANG Yu-Dan, GAO Hui-Yuan, ZHAO Shi-Jie, JIANG Chuang-Dao

Acta Agron Sin. 2010, 36(11): 1941-1949. doi:10.3724/SP.J.1006.2010.01941

Abstract ( 2455 )

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The influences of a systemic signal, from mature leaves, on the photosynthetic characteristics of developing leaves in sorghum seedlings under salt stress were carefully investigated. Salt stress significantly decreased water potential, net photosynthetic rate, stomatal conductance and slightly increased extent of photoinhibition both in mature and newly developed leaves. In newly developed leaves, stomatal density of both adaxial and abaxial surfaces increased. Under non-salt stress condition, water potential both in mature and newly developed leaves was hardly affected when mature leaves exposed to weak light. However, carbon assimilation, stomatal conductance, soluble sugar content decreased markedly and the extent of photoinhibition increased largely in mature leaves and newly developed leaves due to the shading of mature leaves. Meanwhile, stomatal density, mesophyll thickness and surface area of bundle sheath decreased in newly developed leaves when light intensity decreased for mature leaves. In salt-stressed group, changes in photosynthetic structure and function had a similar tendency with that in non-salt stress group, but a further decline in photosynthesis was observed. Two-way ANOVA among these four treatments showed that there was a synergistic effect between salt stress and high irradiance which impaired the photosynthetic ability more heavily and enhanced photoinhibition. Accordingly, we concluded that there is a systemic regulation on the photosynthetic structure and performance of newly developed leaves under salt stress. The enhancement of the light intensity of mature leaves is very important for the improvement of development, carbon assimilation and the alleviation of photoinhibition in newly developed leaves under salt stress.

Comparison of Sugar Yield and Nitrogen Utilization in Tiller Removing or Remaining of Sweet Sorghum

WU Qiu-Ping, WANG Yong-Jun, JIANG Wen-Shun, ZHANG Ji-Wang, LIU Peng, DONG Shu-Ting, WANG Kong-Jun

Acta Agron Sin. 2010, 36(11): 1950-1958. doi:10.3724/SP.J.1006.2010.01950

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Sweet sorghum is one of the most promising renewable energy crop because of its high biomass and soluble sugar content, particularly the intensive resistance to sterile soils and wide adaptability, as well as higher alcohol transformation efficiency compared to other crops, such as maize, sugarcane, rice, sweet beet, et al. To testify whether tillers of sweet sorghum could have distinctive effects on sugar yield, two mostly grown sweet sorghum varieties Rio and Sumac were chosen, which were introduced from America with similar growth duration and higher lodging resistance. Dry matter weight of various organs from anthesis to maturity was measured for plants with all tillers retained and uniculm plants (removed all tillers once they occurred under two plant densities, higher (75000 plants ha^–1) and lower (37500 plants ha^–1). Also the nitrogen (N) contents at both anthesis and physiological maturity periods were determined. The results showed that compared with uniculm plants at either higher or lower densities, plants with tillers had significantly higher biomass and sugar yield, with an averaged increase by 21.9% and 81.6%, 17.1% and 63.8%, respectively. The sugar content in main culms of plant with tillers was close to that removed tillers under higher density, while it deceased significantly under lower density, but the averaged sugar content of all tillers was nearly equivalent to or a little higher than that of plants removed tillers, this may be ascribed to the lower nitrogen content of tillers. The dry matter weight of whole plant consisting of stalks, leaves and sheaths, and panicles was higher than that of uniculm plants, and stalks of plants with tillers remaining maintained higher N accumulation and N distribution at both anthesis and maturing stages, that maybe the primary result of significantly increase in stalk biomass. In conclusion, the tiller remaining plants harvest higher sugar yield accompanied by both increased leaf and panicle biomass, since sugar yield produced by tillers could compensate for the decreased value of main culm caused by competition of nutrient uptake and utilization between main culm and tillers. Retaining tillers probably contribute to explore sugar yield potential of sweet sorghum, and at the same time may reduce the investment cost in cultivation.

Light Reaction Characteristics in Functional Leaves of Liangyoupeijiu in the Reproductive Growth Stage

XU Guang-Hui, CHEN Guo-Xiang, JIANG Yu-Zhen, YU Zhong-Yuan, LV Chuan-Gen

Acta Agron Sin. 2010, 36(11): 1959-1966. doi:10.3724/SP.J.1006.2010.01959

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The chloroplast light reaction characteristics were compared between super-high-yield hybrid rice Liangyoupeijiu and traditional hybrid rice Shanyou 63 intending to provide theoretical insights into physiological basis for high yield. Using fluorescence dynamics analysis and physiological and biochemical research techniques, in the field we systematically studied the primary response, electron transport chain and photophosphorylation during the reproductive period. The results showed that: (1) as compared to Shanyou 63, chlorophyll content in functional leaves of Liangyoupeijiu was 22.90% higher, it had a relatively longer photosynthetic function duration and chla/chlb ratio was 36.78% higher; (2) there was no significant difference in light absorption per unit leaf area of functional leaves, but Liangyoupeijiu maintained a high light energy absorption capacity and long stability period , the number of active reaction centers was more, the energy of heat dissipation was relatively lower, the energy transferred into the electron transport chain was higher; (3) fluorescence analysis showed that structures and status of the body side, the receptor side and the reaction center in PSII performed better than those of Shanyou 63, indicating that Liangyoupeijiu had a higher efficiency in the transforming light energy into electric energy; (4) in addition, oxygen evolution of the chloroplast, activities of electron transport chain and photophosphorylation were significantly higher, indicating that Liangyoupeijiu possessed some advantages in the energy convertsion from electric energy to active chemical energy. With higher light energy absorption, transmission and conversion efficiency, Liangyoupeijiu established a physicological basis of super-high-yield.

Changes of Cell Physiology and Texture of Tobacco Leaf during Bulk Flue- Curing

SONG Chao-Peng, GONG Chang-Rong, WU Sheng-Jiang, LIU Wen-Bo, HE Fan, LIU Chuang, ZHANG Yong-Gang, ZHANG Wei-Jian

Acta Agron Sin. 2010, 36(11): 1967-1973. doi:10.3724/SP.J.1006.2010.01967

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During recent years, the bulk curing barn has rapidly developed and greatly promoted the production of flue-cured tobacco in China. However, some problems, such as the lightening colours, the smoothness and close structure of tobacco leaf, occurred along with the popularizing of flue-curing barn application. In order to meet the quality requirement of the raw material of Chinese-style cigarette, it has been urgent to solve those problems for the tobacco production with high-quality. The changes of the cell wall hydrolases and components play an important role in affecting the physiological changes of post-harvest plant. The differences in the texture of tobacco leaves would affect the organizational structure, morphostructure, internal components and usability. In order to optimize flue-curing technology and to improve the usability of tobacco leaves, we conducted the experiment to investigate the changes of cell physiology and texture of upper tobacco leaves of Zhongyan 100 along with wet and dry bulb temperatures during flue-curing using the electric-heated flue-curing barn designed and made by Henan Agricultural University. The results showed that the respiration rate of tobacco leaf peaked at 38℃ with a value of carbon dioxide content of about 1.80% during curing, and then the respiration rate progressively decreased since 48℃. The activities of pectinesterase and cellulase were higher during 38~54℃ than other temperature conditions. The pectin methylesterases (PME) and cellulase activities were the highest at 42℃, while the polygalacturonase activity (PG) was highest at 48℃. The PG and PME promoted the hydrolysis process of protopectin. Meanwhile, the protopectin, the total pectin and cellulose contents steadily decreased during curing. Texture testing parameters (except cohesiveness) of tobacco leaves changed significantly at the temperatures from 38℃ to 48℃. Among them hardness and chewiness had a maximum value at 42℃, tensile and shear force got their maximum values at 38℃. Cohesiveness, tensile and shear force reached the minimum value at 48℃ during flue-curing. The correlation between the soluble pectin and resilience was significantly negative while the correlations of protopectin, the total pectin, cellulose with resilience, tensile were significantly or highly significantly positive (P<0.05). These results indicated that the texture of tobacco leaves became mealy just due to the decrease of the cell binding force in a way during flue-curing. In other words, it could be resulted from the constant degradation of cell wall substances. This research indicated that dynamic change of shear force parameter was more intuitive. Resilience and tensile could be used as texture parameters to study the change of cell physiology of tobacco leaves. The main factors to make a significant difference in texture of tobacco leaves were the changes of cell physiology during flue-curing.

Effect of Controlled Release Fertilizer on Physiological Characteristics, Yield and Quality of Peanut in Slope Field

WANG Yan-Hua, DONG Yuan-Jie, QIU Xian-Kui, HU Guo-Qing

Acta Agron Sin. 2010, 36(11): 1974-1980. doi:10.3724/SP.J.1006.2010.01974

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Slope field has been one of the major factors limiting peanut (Arachis hypogea) production in Shandong province. Improving fertilizer use efficiency and reducing nutrients loss play an important role to obtain high yield and quality in slope field. Previous studies have shown controlled release fertilizer can release nutrients to soil during peanut growing season and improve yield and quality.In the experiment, four treatments of man-made slopes in 0°, 5°, 10° and 15° were set in field conditions. The results showed that the controlled release fertilizer increased the leaf chlorophyll content, net photosynthetic rate, transpiration rateandstomatal conductance and decreased stomatal limitation (L_s) in the leaf during the late growth stage, and improved the accumulation amount and use efficiency of N, P and K, and increased pods per plant by 7.1%–36.0%, 100-kemel weight by 5.8%–9.7%, pod yield by 17.1% and total biomass by 3.8% when the slope was 10°, pod yield by 15.7% and total biomass by 15.7% when the slope was 15°. The controlled release fertilizer also improved the protein and fat contents. In addition, when the slope increased, the leaf chlorophyll content, net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), the accumulation amount and use efficiency of N, P and K, pod yield and total biomass under using the two kinds of fertilizers decreased by a certain extent. But the differences for the same fertilizer among different slopeswere not significant.

RESEARCH ACTIVITIES

Estimation of Chlorophyll and Nitrogen Contents in Cotton Leaves Using Digital Camera and Imaging Spectrometer

WANG Fang-Yong, WANG Ke-Ru, LI Shao-Hun, CHEN Bing, CHEN Jiang-Lu

Acta Agron Sin. 2010, 36(11): 1981-1989. doi:10.3724/SP.J.1006.2010.01981

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Leaf chlorophyll and nitrogen concentrations of cotton (Gossypium hirsutum L.) are important indicators of plant N status. They can provide valuable insights into the physiological performance of leaves. The objectives of this study were to determine the relationships between chlorophyll, nitrogen, SPAD readings and leaf spectral and color parameters in cotton. Spectral and color parameters for the non-destructive estimation of chlorophyll, nitrogen contents and SPAD readings were obtained by using digital camera (Olympus C-5060) and imaging spectrometer (MSI200) so a wide range of them was established in cotton. The dataset was separated into two parts using for calibration (n=100) and validation (n=60), respectively. Therefore, a systematic analysis was undertaken on quantitative relationships of chlorophyll, nitrogen, SPAD readings to major spectral indices, such as the ratio index (RI), normalized difference index (ND) and difference index (DI), composed of any two wavelengths with original reflectance and color parameters. The results indicated that the maximum sensitivity of reflectance to variation in chlorophyll, nitrogen contents and SPAD readings was found in the far-red wavelength region at 710 nm and in the red wavelength region (R) for two sensors, respectively. Furthermore, spectral indices could improve the prediction ability obviously, and difference indices (DI and R-B) of different sensors composed of blue and red wavelengths gave a better prediction performance. The models to retrieve chlorophyll, nitrogen contents and SPAD readings using DI were the most feasible models with the maximum determination coefficients (R²) and the minimum RMSE, especially, DI (R₄₄₀, R₇₁₀), DI (R₄₄₀, R₇₁₀), DI (R₄₂₀, R₇₁₀), DI (R₄₂₀, R₇₂₀) and DI (R₄₉₀, R₇₁₀) were the optimum indices for the models of chlorophyll a+b, chlorophyll a, chlorophyll b and N, and SPAD readings, respectively. R-B was the optimum index of digital camera but its prediction performances were lower than these of DI. Additional, b* (CIE 1976 L*a*b* color model) and S (HSI color model) were the optimum color parameters, and the prediction ability of b* was lower than that of DI. However, the prediction performance of S was relative weak with the highest RRMSE and the lowest R². Thus, measurements of leaf reflectance and color in visible range by using digital camera and imaging spectrometer may provide a real-time and accurate means of estimating leaf chlorophyll and nitrogen contents and monitoring of cotton plant nitrogen status and N fertilizer management in the field.

Inquisition of MiniMax, an Early Maturing, Dwarf, and Small-Seed Genotype, as a Research Model in Soybean

QU Meng-Na, SUN Shi, WU Cun-Xiang, FEI Zhi-Hong, GUO Yu-Hua, HOU Wen-Sheng, HAN Tian-Fu

Acta Agron Sin. 2010, 36(11): 1990-1997. doi:10.3724/SP.J.1006.2010.01990

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