Table of Content

12 February 2015, Volume 41 Issue 02

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REVIEW

Analysis of Concepts and Categories of Plant Phenome and Phenomics

PAN Ying-Hong

Acta Agron Sin. 2015, 41(02):  175-186.  doi:10.3724/SP.J.1006.2015.00175

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Plant phenotyping is a key link in understanding gene function and environmental effects, and with development of plant function genomics and crop molecular breeding, the traditional phenotypic observation has become the main bottleneck. High-throughput plant phenome analysis technology and plant phenomics study is an effective way to solve this problem. Although plant phenome analysis is becoming a hot spot at home and abroad, relevant concepts are still relatively fuzzy, and this situation hinders the development of this emerging discipline. In this paper, the relevant concepts and categories of plant phenome and plant phenomics were analyzed, and the new concepts such as quasi-phenome, identifiable traits, mapped traits, and tolerance of plant phenotype to the changes of inheritance and environment, were introduced. And, plant phenome was defined as “all of physical, physiological and biochemical characteristics and traits which are decided or influenced by genome and environments, and can reflect the plant structures and compositions, or reflect the processes and results of plant growth and development”, and plant phenomics as “the comprehensive controls, complete collections and systematic analyses of plant phenome informations and related environmental parameters”. The scopes, directions, and top design principles of plant phenomics research, were also discussed.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Identification of QTL Associated with Vitamin E Content in Soybean Seeds

ZHANG Hong-Mei,LI Hai-Chao,WEN Zi-Xiang,GU He-Ping,YUAN Xing-Xing,CHEN Hua-Tao,CUI Xiao-Yan,CHEN Xin,LU Wei-Guo

Acta Agron Sin. 2015, 41(02):  187-196.  doi:10.3724/SP.J.1006.2015.00187

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Vitamin E has effects on human immunity, anti-cancer and prevention of cardiovascular disease. Vitamin E from soybean has the advantages of higher security and higher human body absorption rate. The objective of the present study was to map the additive，additive × additive (epistasis), additive × year and epistasis × year QTLs for vitamin E and relative tocopherol contents with the RIL population BIEX (Essex×ZDD2315) using HPLC (high performance liquid chromatography) method and software QTLNetwork 2.1. Eight additive QTLs and twelve additive × additive (epistasis) QTLs were detected for vitamin E and relative tocopherol contents. The contributions to the phenotypic variances of additive QTL and epistatic QTL pairs were 8.68% (two QTLs) and 15.57% (four pairs) for α- tocopherol, 8.59% (two QTL) and 11.57% (two pairs) for γ-tocopherol, 5.44% (one QTL) and 17.61% (three pairs) for δ-tocopherol and 11.39% (three QTL) and 9.48% (three pairs) for total vitamin E contents, respectively. Those of additive and epistatic QTLs by year interaction were not found. The accumulated contribution of the unmapped minor QTLs was 66.16%–75.32%, indicating the variance of unmapped minor QTLs accounting for more than two thirds. In genetic composition, undetected minor QTLs accounted for a considerably large part additive QTLs and epistatic QTLs were nearly equal in α-tocopherol, γ-tocopherol, δ-tocopherol and total vitamin E contents. Accordingly, in breeding for vitamin E contents, the strategy of pyramiding multiple QTLs, both additive and epistatic, by using marker-assisted selection combined with accumulating minor effect QTLs through conversional procedures should be considered.

Genetic Diversity of Registered Wheat Varieties in Henan Province Based on Pedigree and Single-Nucleotide Polymorphism

CAO Ting-Jie,XIE Jing-Zhong,WU Qiu-Hong,CHEN Yong-Xing,WANG Zhen-Zhong,ZHAO Hong,WANG Xi-Cheng,ZHAN Ke-Hui,XU Ru-Qiang,WANG Ji-Rui,LUO Ming-Cheng,LIU Zhi-Yong

Acta Agron Sin. 2015, 41(02):  197-206.  doi:10.3724/SP.J.1006.2015.00197

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To understand the genetic diversity of wheat varieties in Henan Province at whole genome level, we selected 96 registered wheat varieties in the past decade for SNP genotyping using the Illumina 90k iSelect SNP chip. The results showed that 47.39% of the SNPs (38 661 out of 81 587) were polymorphism between varieties. The genome distribution of polymorphic SNPs showed a tendency of B > A > D. The genetic similarity of the 96 varieties ranged from 0.552 to 0.998 with an average value of 0.719. However, genetic similarity of 0.652 to 0.812 was found for 94.3% of the tested varieties, indicating highly similarity for most of the varieties in Henan province. The 96 wheat varieties could be classified as seven groups by UPGMA analyses. Based on pedigree and SNP analyses, very narrow genetic background was observed for the registered varieties in the past decade in Henan province. It is an urgent task for wheat breeders to explore and introduce diversified germplasm resources into wheat breeding program to increase the yield potential and stress tolerance in the future.

Molecular Cytogenetic Characterization of Triticum–Psathyrostachys Substitution Line DH2322

WANG Xiu-Juan,CHEN Xin-Hong,PANG Yu-Hui,JING Fan,ZHANG Jun,HU Si-Yuan,ZAN Kai,WU Jun,YANG Qun-Hui,ZHAO Ji-Xin *

Acta Agron Sin. 2015, 41(02):  207-213.  doi:10.3724/SP.J.1006.2015.00207

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A wheat–P. huashanica alien substitution line DH2322 was isolated from the F4 progeny of heptaploid hybrid H8911 × Triticum durum cv. D4286 and identified by using SCAR markers, genomic in situ hybridization (GISH) , SSR markers, and STS markers. The rusults using SCAR marker RHS141 showeded that DH2322 carrys chromosome derived from P. huashanica. Cytogenetic observation indicated that DH2322 has a chromosome karyotype of 2n = 42 = 21 II. GISH showed that DH2322 is a line with 40 chromosomes from wheat and two Ns chromosomes from P. huashanica, which formed a ring bivalent in PMC at metaphase I. Analysis with SSR and STS primers showed that the wheat chrom osome 2D in DH2322 was substituted by the chromosome 2Ns from P. huashanica. Evaluation of the agronomic traits showed that DH2322 presented favorable agronomic traits in spike length and kernels per spike. Development of this new germplasm will be useful for wheat breeding programs in the future.

Evaluation of Sugarcane Test Environments and Ecological Zone Division in China Based on HA-GGE Biplo

LUO Jun,XU Li-Ping,QIU Jun,ZHANG Hua,YUAN Zhao-Nian,DENG Zu-Hu,CHEN Ru-Kai,QUE You-Xiong

Acta Agron Sin. 2015, 41(02):  214-227.  doi:10.3724/SP.J.1006.2015.00214

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The yield data of 24 sugarcane cultivars grown at 14 test locations were analyzed by combining analysis of variance and heritability-adjusted GGE (HA-GGE) biplot to study the genotype (G), environment (E), and genotype×environment (GE) effects on yield variation. Besides, the 14 test locations were evaluated for their discriminating ability, representative ability and desirability index, and grouped into ecological zones based on the GGE biplot patterns. The results showed that the effect of environments on yield was higher than that of G and GE, and the genotype by location interaction was the greatest while genotype by year interaction the least within GE. The GGE biplot analysis revealed that Suixi of Guangdong Province and Chongzuo of Guangxi Province were the two most ideal test locations for developing and/or recommending cultivars for the whole region. In contrast, Laibin and Liuzhou of Guangxi Province were undesirable for selection and variety recommendation for the whole region. The other relatively desirable test locations included Fuzhou and Zhangzhou of Fujian Province, Zhanjiang of Guangdong Province, Baoshan, Lincang, and Ruili of Yunnan Province, followed by the four less desirable test environments, Baise and Hechi of Guangxi Province, Lingao of Hainan Province and Kaiyuan of Yunnan Province. According to the results from HA-GGE analysis, the sugarcane ecological zones in China could be divided into three subregions, the first is the ecological zone of southern China inland, represented by Baise, Hechi, Laibin and Liuzhou of Guangxi Province, the second one is the ecological zone of southwest plateau, represented by Baoshan, Kaiyuan, Lincang and Ruili of Yunnan Province, and the third one is the ecological zone of coastal southern China, represented by Fuzhou and Zhangzhou of Fujian Province, Zhanjiang and Suixi of Guangdong Province, and Chongzuo of Guangxi Province. The present study fully displayed the successful application of HA-GGE biplot in trial environment evaluation and also provided the theoretical basis for the decision-making in ecological zone division.

Expression Changes of Transcription Factors in Susceptible and Resistant Upland Cotton Cultivars (Gossypium hirsutum L.) in Response to Fusarium wilt

HAN Ze-Gang,ZHAO Zeng-Qiang,HE Lan-Lan,CHAI Meng-Liang,LI Hui-Hui,ZHANG Wei

Acta Agron Sin. 2015, 41(02):  228-239.  doi:10.3724/SP.J.1006.2015.00228

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The Solexa sequencing was used to study the expression changes of transcription factors and their families in upland cotton cultivars susceptible and resistant to Fusarium wilt. A total of 39 transcription factor families and 433 transcription factors in Zhongmiansuo 12 and 58 transcription factor families and 588 transcription factors in Xinluzao 7 were changed in expression in at least one comparison group induced by Fusarium wilt. The number of transcription factor families responsed to Fusarium wilt was more in Xinluzao 7 than in Zhongmiansuo 12, and the number of down-regulated genes was more than that of up-regulated genes in two varieties. After the induction by Fusarium wilt, in the process of time, the number of transcription factor families and transcription factors responsed to the Fusarium wilt in two cultivars showed the same changing trend of increase first and decrease then. The maximum number was reached after six hours in Zhongmiansuo 12, while at three hours after the inducing in Xinluzao 7. Among six comparison groups, there were nine overlapping transcription factors in six transcription factor families of Zhongmiansuo 12 and Zhongmiansuo 31 overlapping transcription factors in 17 transcription factor families of Xinluzao 7. The expression of transcription factor showed strong cultivar specificity among varieties tolerant to Fusarium wilt. Except for 37 transcription factor families shared between two cultivars, two transcription factor families were unique to Zhongmiansuo 12 and Zhongmiansuo 15 transcription factor families were unique to Xinluzao 7.

Cloning and Expression of Three Genes Involved in the Biosynthesis of Chlorophyll in Different Albescent Stages of “Baiye 1”

MA Chun-Lei,YAO Ming-Zhe,WANG Xin-Chao,JIN Ji-Qiang,MA Jian-Qiang,CHEN Liang

Acta Agron Sin. 2015, 41(02):  240-250.  doi:10.3724/SP.J.1006.2015.00240

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Chlorophyll is one of the main pigments participating in photosynthesis in plant chloroplasts, and its biosynthesis is crucial for higher plant. In this article, we cloned and characterized three important genes involved in the biosynthesis of chlorophyll which were CsGluTR, CsChlS, and CsCAO (GenBank accession number HQ660371, HQ660370, and HQ660369) lead on the results of cDNA microarray hybridization. The full-length cDNA of CsGluTR was 2165 bp, containing a 1665 bp ORF encoding a 554 amino acids protein, and its 3′untranslated region had an obvious polyadenylation signal. The deduced protein molecular weight was 60.6 kD and its theoretical isoelectric point was 8.78. The obtained cDNA of CsChlS was 1463 bp in length, containing a 1125 bp ORF which encoded 374 amino acid residues. The deduced protein molecular weight was 40.5 kD and its theoretical isoelectric point was 8.58. The full-length of CsCAO was 2146 bp, containing a 1611 bp ORF encoding a 536 amino acids protein. The deduced amino acid sequence of CsGluTR, CsChlS, and CsCAO from tea plant shared high identity with those of other species, for instance the similarity of 79%, 90% and 77 % with Vitis vinifera, respectively. The result of Real-time RT-PCR analysis showed a coordinated expression of CsChlS and CsCAO, which was corresponded with the change of the albino phenotype. However, there were small changes in the expression level of CsGluTR between the normal and albino leaves. These results implied that the biosynthesis of chlorophyll is completely hindered in albino leaves, causing the decline of pigment content and the albino phenotype.

Association Analysis of Solvent Retention Capacity in Soft Wheat

ZHANG Yong,ZHANG Xiao,GUO Jie,GAO De-Rong,ZHANG Bo-Qiao*

Acta Agron Sin. 2015, 41(02):  251-258.  doi:10.3724/SP.J.1006.2015.00251

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Solvent retention capacity (SRC) is an important index for identification and evaluation of soft wheat varieties. This study aimed at identifying SRC associated markers for marker-assisted selection. One hundred and seventy-six wheat varieties (lines) in different hardness types were screened with 236 pairs of SSR primers and their SRC values of lactic acid, water, sucrose, and sodium carbonate were evaluated in three growing seasons in Lixiahe, Jiangsu Province. The association analysis was carried out using the mixed-linear model (MLM). A total of 1340 fragments were amplified on the 236 SSR loci with an average of 5.5 alleles per locus. The average polymorphism information content was 0.4663. Twenty-eight loci were identified to be associated with lactic acid SRC (13), water SRC (7), sucrose SRC (6), and sodium carbonate SRC (2) at the significant level of P < 0.005, and a single locus explained 3.19%–21.84% of phenotypic variation. Marker gwm642 associated with WSRC was detected in three years. Some favorable alleles associated with SRCs were found, such as gwm642-A186, gwm642-A188, and gwm337-A178 for reducing water SRC, gwm337-A178 and gwm337-A186 for reducing sucrose SSRC, and cfa2257-A129 for reducing sodium carbonate SRC. These results are informative for marker-assisted selection on SRC properties in wheat.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Structural Characterization and Abiotic Stress Response of Soybean TRK-HKT Family Genes

YIN Gui-Xiang,ZHANG Lei*,SHE Mao-Yun

Acta Agron Sin. 2015, 41(02):  259-275.  doi:10.3724/SP.J.1006.2015.00259

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Plant TRK-HKT family genes are involved in Na+/K+ transportation and regulation to abiotic stresses. We used six soybean varieties with different potassium use efficiencies (PUE) as materials, cloned four soybean TRK-HKT family genes (GmHKT1;1, GmHKT1;2, GmHKT1;3, and GmHKT1;4) via in silico, and explored the genes structure and expression under low potassium treatment and abiotic stresses with qRT-PCR technique. The results showed that the expression level of GmHKT1;2 was higher than those of the other three members in the roots of soybean seedlings under low potassium stress, which was more obvious in the roots of the soybean varieties with high PUE. Meanwhile, GmHKT1;2 showed high response to various abiotic stresses (chilling, drought, high salinity, and ABA). Protein structure prediction showed that only GmHKT1;2 contains four MPM domains and a "funnel-like" structure of four conserved amino acid residues spatially, which acted as K+/Na+ transport channel and provided energy for transportation, together with the adjacent ATP binding domain. Analysis on gene structure indicated that there are three exons and two introns in all four members with a significant difference in the size of exon I and intron I, resulting in the genomic DNA (gDNA) difference in lenghth of the different GmHKT genes. Promoter analysis revealed that upstream promoter elements of soybean TRK-HKT family genes contained important cis-acting regulatory elements involved in the functional target to seed-specific expression, and response to hormone and diverse abiotic stresses. In evolution, soybean TRK-HKT family genes belonged to clade I with conserved Ser–Gly–Gly–Gly motif.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Effect of Variety Mixure Planting on Powdery Mildew Controlling as Well as Yield and Protein Contents in Common Wheat

JIANG Yan-Tao,XU Tao,DUAN Xia-Yu*,ZHOU Yi-Lin

Acta Agron Sin. 2015, 41(02):  276-285.  doi:10.3724/SP.J.1006.2015.00276

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The knowledge of variety mixture planting in the field on the effects of powdery mildew disease and wheat yield and quality will facilitate the utilization of variety diversity to control wheat diseases. In the 2011–2012 and 2012–2013 growing seasons, we selected eight commercial wheat varieties with large differences in genetic background and disease resistance to test the feasible pattern of variety mixture in the field. In each mixture pattern containing one (control), three, four, five, six, seven, and eight varieties, wheat plants were exposed to mixed powdery mildew isolates. The area under disease progress curve, plot yield, thousand-grain weight and crude protein content in grain were measured. For disease control, four-variety mixture pattern had the best efficacy. However, the mixture patterns with seven or more varieties exhibited also good efficacy. In the 2011–2012 growing season, 42.4% of the mixture patterns were effective with relative efficacy ranging from 1.2% to 26.8%. Meanwhile, 50.0% of the mixture patterns had the effect of yield increase (0.2–14.6%) compared with the control. In the 2012–2013 growing season, 75.0% of the mixture patterns were effective with the efficacy ranging from 1.8% to 45.4% and 71.4% of the mixture patterns resulted in increased yield (0.9–16.6%). Zhoumai 18 was the best component in mixtures having good control against powdery mildew and positive effects on grain yield and protein content. Interactions among the mixture components were also observed, and such interaction had impacts on powdery mildew controlling and wheat yield.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Canopy Structure and Photosynthetic Characteristics of Yongyou Series of Indica-Japonica Hybrid Rice under High-yielding Cultivation Condition

JIANG Yuan-Hua,XU Ke,ZHAO Ke,SUN Jian-Jun,WEI Huan-He,XU Jun-Wei,WEI Hai-Yan,GUO Bao-Wei,HUO Zhong-Yang,DAI Qi-Gen,ZHANG Hong-Cheng*

Acta Agron Sin. 2015, 41(02):  286-296.  doi:10.3724/SP.J.1006.2015.00286

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Compared with japonica hybrid rice cultivars(B), conventional japonica rice cultivars (C) and indica hybrid rice cultivars (D), Yongyou series of indica-japonica hybrid rice cultivars (A) were adopted to analyze the lightened posture of leave, light distribution of canopy and photosynthetic characteristics of plant systematically. Results were as follows: (1) leaf length, leaf width of top three leaves showed the trend of A>B>D>C, canopy extinction coefficient showed the trend of C>D>B>A, leaf basic angle of top three leaves and relative height of the largest leaf area density were D>A,>B>C, lower canopy leaf area density was C>B>A>D, plant height and largest leaf area density showed the trend of A>D>B>C, leaf drop angle of top three leaves showed the trend of D>B>C>A, upper canopy leaf area density observed D>A>B>C, lower canopy relative light showed the trend of A>B>C>D, lower canopy relative light and canopy average relative light showed the trend of B>A>C>D; (2) population LAI and high valid leaf area rate showed the trend of D>A>B>C at heading, valid leaf area rate, spikelets per cm2 leaf area, filled grains per cm2 leaf area, total biomass, economic yield, Chlorophyll (a+b) content, carotenoid content, PSII actual photochemical efficiency, net photosynthetic rate, enzyme activities of SOD, POD and CAT after heading showed the trend of A>B>C>D, harvest index and MDA content showed the trend of D>C>B>A. Therefore, compared with other three types of rice, Yongyou Series of indica-japonica hybrid rice had significant advantages in the canopy structure and photosynthetic characteristics, which are both normal ecological and physiological bases of high yield, and maybe an important way to improve the population productivity of inter-subspecific hybrid rice.

Changes in Carbohydrate Accumulation and Activities of Enzymes Involved in Starch Synthesis in Maize Kernels at Different Positions on an Ear during Grain Filling

XU Yun-Ji,GU Dao-Jian,QING Hao,ZHANG Hao,WANG Zhi-Qin,YANG Jian-Chang*

Acta Agron Sin. 2015, 41(02):  297-307.  doi:10.3724/SP.J.1006.2015.00297

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Kernels at the upper position of a maize ear usually show slower filling rate and lower weight than those at the basal and middle positions. The mechanism is little understood. The objective of this study was to understand if changes in carbohydrate accumulation and activities of the enzymes involved in starch synthesis in the kernels at different positions on a maize ear were associated with grain filling. A maize cultivar Denghai 11 was planted in spring and summer. Contents of the soluble sugar, sucrose and starch and the activities of the adenosine diphosphoglucose pyrophosphorylase (AGPase), starch synthase (StS), and starch branching enzyme (SBE) in kernels at different positions on an ear and their relationships with grain filling rate were determined. The results showed that kernel number per ear, 100-kernel weight, and grain yield were more or higher for the spring maize than for the summer maize. Although the grain yield was different between the spring maize and the summer maize, the maximum kernel filling rate, mean kernel filling rate, 100-kernel weight, the contents of both soluble sugar and sucrose in kernels, the maximum starch accumulation rate and mean starch accumulation rate in kernels all exhibited an order of basal position > middle position> upper position. The activities of AGPase, StS and SBE in kernels at different positions on an ear showed the changes of single peak curves, and the peak and mean enzymatic activities in kernels at the upper position were significantly lower than those at both middle and basal positions. The starch accumulation rate and kernel filling rate were very significantly and positively correlated with activities of AGPase, StS and SBE in kernels. The results suggested that a smaller starch accumulation rate and lower weight for the kernels at the upper position on a maize ear are mainly attributed to lower activities of the enzymes involved in starch synthesis in these kernels. A higher kernel weight for the spring maize is closely associated with its stronger ability of starch synthesis in the kernels.

Diversity Analysis of Rhizosphere Microflora of Wild R. glutinosa Grown in Monocropping for Different Years

WU Lin-Kun,HUANG Wei-Min,WANG Juan-Ying,WU Hong-Miao,CHEN Jun,QIN Xian-Jin,ZHANG Zhong-Yi,LIN Wen-Xiong

Acta Agron Sin. 2015, 41(02):  308-317.  doi:10.3724/SP.J.1006.2015.00308

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The soils sampled from the four different plots, including the newly planted, the two-year monocultured, the wild R. glutinosa and the control without growing R. glutinosa, were used to study the changes in microbial biomass and community composition using phospholipid fatty acid (PLFA) and terminal restriction fragment length polymorphism (T-RFLP) analyses. PLFA analysis indicated that the soil microbial community composition was significantly different among the R. glutinosa with different years of monoculture. Compared with the newly planted soil, the total PLFA content and the ratio of bacteria/fungus in two-year monocultured soil greatly declined. Further analysis by T-RFLP also displayed the distinct differences in rhizospheric bacterial community structure of R. glutinosa. The microbial compositions from the wild and the newly planted R. glutinosa soils tended to be more similar. It was found that the bacteria including Proteobacteria and Firmicutes were predominant in the wild and newly planted R. glutinosa soils. Some beneficial biocontrol bacteria (such as Bacillus, Pseudomonas, etc.) gathered in the rhizosphere of the wild and newly planted R. glutinosa. However, a large number of pathogenic bacteria bred in the rhizosphere of the two-year monocultured R. glutinosa, such as Clostridium sp., Flexibacter polymorphus and Clostridium ghoni, and the number of beneficial bacteria and cellulose degradation bacteria decreased. Furthermore, qRT-PCR analysis verified that the total number of Pseudomonas was much higher in the wild and newly planted R. glutinosa soils than in the two-year monocultured soil. In conclusion, the pathogenic microbes breed seriously in the rhizospheric soil of wild R. glutinosa under the monoculture regime, and yet the number of beneficial bacteria decline, resulting in weakened ability of wild R. glutinosa to resist the diseases so that the two-year monocultured wild R. glutinosa grows abnormally and its yield is decreased drastically.

Morphological Structure Model of Leaf Space Based on Biomass at Pre-Overwintering Stage in Rapeseed (Brassica napus L.) Plant

ZHANG Wei-Xin,CAO Hong-Xin,ZHU Yan,LIU Yan,ZHANG Wen-Yu,CHEN Yu-Li,FU Kun-Ya

Acta Agron Sin. 2015, 41(02):  318-328.  doi:10.3724/SP.J.1006.2015.00318

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Rapeseed morphogenesis at pre-overwintering stage is the basis of growth and development of rapeseed in whole growth stage, and the leaf blades are important vegetative organ in this stage. To quantify the relationships between rapeseed plant architecture indices and the corresponding organ biomass, we used three cultivars including (V1) Ningyou 18 (conventional variety), (V2) Ningyou 16 (conventional variety), and (V3) Ningza 19 (hybrid) in the field experiments, and designed treatment of variety-fertilizer, variety-fertilizer-density, and variety tests in 2011–2012 and 2012–2013, with three fertilizer levels of no fertilizer, normal fertilizer (N, P2O5, K2O are 90 kg ha–1), and high fertilizer (N, P2O5, K2O are 180 kg ha–1), and three density levels of D1 (6×104 plant ha–1), D2 (1.2×105 plant ha–1), and D3 (1.8×105 plant ha–1). Morphological indices were determined at pre-overwintering stage, the biomass-based rapeseed aboveground structure model was established with morphological indices, and the relationships between leaf blade indices and leaf blade biomass were analyzed. The models were verified using independent experiment data in 2011–2012, and 2012–2013, showing that the simulated values from the rapeseed plant leaf space morphological structure models, such as leaf blade length, leaf blade width, leaf blade bowstring length, leaf blade petiole length, and leaf blade angle from 2011 to 2012 were goodness of fit to observed values, and their da values and RMSE values were –0.231 cm, 2.102 cm (n=63); –0.273 cm, 0.484 cm (n=63); –0.343 cm, 1.963 cm (n=63); 0.412 cm, 2.095 cm (n=36); –0.635 cm, 1.006 cm (n=27); 4.421°, 14.734° (n=63); 6.642°, 21.817° (n=63), respectively. The correlation between observation and simulation in the morphological indices were significant at P<0.001, but the dap values were less than 5% for the leaf blade length and the leaf blade bowstring length, which indicated that these models’ accuracy is high. The simulated values of the models had better consistency and better reliability with the observed values at pre-overwintering stage except for petiole length of the short-petiole leaves, leaf tangent angle, leaf bowstring angle, and the CPLB (partitioning coefficient of blade dry weight) under the condition of no fertilizer.

Effects of Waterlogging on Photosynthetic Characteristics of Summer Maize under Field Conditions

REN Bai-Zhao,ZHU Yu-Li,LI Xia,FAN Xia,DONG Shu-Ting,ZHAO Bin,LIU Peng,ZHANG Ji-Wang*

Acta Agron Sin. 2015, 41(02):  329-338.  doi:10.3724/SP.J.1006.2015.00329

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Two summer maize hybrids Zhengdan 958 and Denghai 605 were used in the field experiment to explore the effects of waterlogging with different durations (3 and 6 days) on photosynthetic characteristics of summer maize at the three-leaf stage (V3), six-leaf stage (V6), and ten days after the tasseling stage (10VT). Results showed that leaf area index (LAI), chlorophyll content, net photosynthetic rate (P_n), stomatal conductance (G_s), and intercellular CO₂ concentration (C_i) were decreased significantly by waterlogging. P_n,G_s, and C_i of two hydrids decreased mostly in the treatment of waterlogging for 6 days at V3, with 21.24%, 33.65%, and 16.49% in Denghai 605 and 24.50%, 32.31%, and 10.99% in Zhengdan 958, respectively. F_v/F_m, F_m/F_o, and Φ_PSII significantly decreased in the treatment of waterlogging for 6 days at V3, with 16.86%, 17.12% and 11.67% in Denghai 605 and 13.58%, 21.40% and 22.52% in Zhengdan 958 respectively, resulting in the decrease of grain yield ultimately by 41.51% in Denghai 605 and 40.96% in Zhengdan 958. The greatest yield losses from waterlogging occurred at V3, the following was at V6 and 10VT. The waterlogging effect increased with increasing waterlogging duration.

Effect of Cropping Systems on Microbial Diversity in Black Loessial Soil Tested by 454 Sequencing Technology

CAI Yan, HAO Ming-De, ZHANG Li-Qiong, ZANG Yi-Fei, HE Xiao-Yan

Acta Agronomica Sinica. 2015, 41(02):  339-346.  doi:10.3724/SP.J.1006.2015.00339

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ment lasted 27 years, we analyzed the diversity changes of bacteria and fungi in black loessial soil under different cropping systems in Loess Plateau using 454 sequencing technology. The results showed that bacterial diversity showed wheat-pea rotation> continuous wheat>fallow land>continuous alfalfa, and fungal diversity showed continuous wheat≈continuous alfalfa>fallow land>wheat-pea rotation under low nutritional stress with no fertilization. In the conditions of application of nitrogen fertilizer and phosphorus fertilizer, microbial diversity generally showed an decreasing and then increasing trend in long-period rotation of wheat–alfalfa (alfalfa→ alfalfa→ alfalfa→ alfalfa→ potato→ wheat→ wheat→ wheat, eight years as a rotation period); Chao index and Shannon index of the 4th year alfalfa or the 1st year wheat were the lowest, and those of the 2nd year wheat were the maximum, with the bacteria Chao index and fungi Shannon index of 22.0% and 79.2% higher than those of continuous wheat, respectively. Microbial diversity generally showed an increasing trend in short-period rotation of wheat–sainfoin (sainfoin→wheat→ wheat, three years as a rotation period), and that of the 2nd year wheat after sainfoin was the maximum, with fungi Chao index and Shannon index of 50.8% and 51.0% higher than that of continuous wheat respectively. Wheat-forage legumes rotation could improve the microbial diversity significantly in Loess dryland areas.