Table of Content

12 July 2017, Volume 43 Issue 07

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

dsDNA Fluorescent Quantification and Genotyping in Common Wheat by FLUOstar System

XIAO Yong-Gui,Susanne DREISIGACKER,Claudia NU?EZ-RíOS,HU Wei-Guo,XIA Xian-Chun,HE Zhong-Hu

Acta Agron Sin. 2017, 43(07):  947-953.  doi:10.3724/SP.J.1006.2017.00947

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Quantitative analysis on double-stranded DNA (dsDNA) lays a foundation in molecular biology research in plants, particularly important for genotyping in molecular breeding. The objective of this study was to establish standard curve for fluorescence quantitative analysis by lambda DNA, to compare the difference between dsDNA value in fluorescence system and ultraviolet spectrophotometry, and to identify the allelic variations of rust resistance genes in wheat. The fluorescent dye could be efficiently performed in the quantitative analysis with micro dsDNA concentration (< 1.1 ng ?L?1). However, the fluorescent dye could lead to uncertainty of original concentrations of wheat leaf and grain genome DNA, due to more fold serial dilutions for higher DNA concentration. A downward tendency was happened in fluorescent intensity when fluorescent reaction volume was tapered, which influenced the accuracy of DNA concentration. The volume of reaction system mixed nucleic acid and fluorescent dye should be more than 200 ?L for accurate determination of micro dsDNA. For genotyping on PCR products, the volume of fluorescent reaction system should be more than 40 ?L. FLUOstar could be used for identifying the dominant marker, for instance csSr32#1 (Sr32) and IB-267 (Sr50), its accuracy was 100% in correspondence with that from agarose gel electrophoresis. Co-dominant marker with the characteristic of peculiarity and major difference in amplified fragment length ( ≥100 bp), such as We173 (Yr26), could also be identified by fluorescent analysis. Compared with agarose gel electrophoresis method, fluorescent method have a simple, convenient, and rapid oparetion with high repeatability, and can be used for segregating generations in marker-assisted breeding.

Association Analysis and Exploration of Elite Alleles of Mechanical Harvest-Related Traits with SSR Markers in Upland Cotton Cultivars (Gossypium hirsutum L.)

WANG Juan,DONG Cheng-Guang,LIU Li,KONG Xian-Hui,WANG Xu-Wen,YU Yu

Acta Agron Sin. 2017, 43(07):  954-966.  doi:10.3724/SP.J.1006.2017.00954

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Cotton suitable for mechanical harvest should have higher requirement in traits, for example, shorter growth period, ideal plant type and high sensitivity to defoliant. A total of 214 pairs of SSR with high polymorphism and uniform distribution on whole genome were used to scan polymorphism in 118 cotton varieties with one or more mechanical harvest-related traits. Molecular marker data and six phenotypic traits were analyzed by the method of MLM (mixed linear model) in Tassel 5.0 on the basis of population structure, analysis loci with elite allelic variation and typical materials carrying elite alleles were identified based on phenotypic effect values. We detected 460 alleles and 905 genotypes. The average genetic diversity index was 0.5151, and the average polymorphic information content (PIC) per marker was 0.4587. Ninety-nine markers achieved the aforementioned average values accounted for 46.3% of the total markers, shows that the SSR markers have more allelic variance and higher genetic diversity. All the 118 cotton varieties were divided into four subgroups by analysis of population genetic structure. There was no corresponding relation between each kind of group of materials and the geographical source. A total of 124 loci (P<0.05) and 20 loci (P<0.01) associated with mechanical harvest-related traits were detected by association analysis, with explained variance ranging from 2.23% to 14.15% and from 4.84% to 14.15% respectively. Based on the results of this study, we identified 11 typical materials, including Xi 7, Jinken 9, Y11, Yumian 18, AY-4, K2, Chaoyang 2, DZ22, Zhongmiansuo 43, C2, Guanrongchangzao B14. The elite alleles and resources can be useful for marker-assisted selection breeding.

Cytological Identification and Chromosome Constitution Analyses of Ten Octoploid Trititrigia Accessions

QI Xiao-Lei,BAO Yin-Guang,LI Xing-Feng,QIAN Zhao-Guo,WANG Rui-Xia,WU Ke,WANG Hong-Gang

Acta Agron Sin. 2017, 43(07):  967-973.  doi:10.3724/SP.J.1006.2017.00967

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Developing new octoploid Trititrigia is of great significance for using Thinopyrum intermedium to the genetic improvement of common wheat. Ten octoploid Trititrigia accessions, i.e., Shannong TE256, Shannong TE259, Shannong TE261, Shannong TE262, Shannong TE263, Shannong TE265, Shannong TE266, Shannong TE267-1, Shannong TE270 and Shannong TE274, were developed from the progenies of the cross between Thinopyrum intermedium and common wheat variety ‘Yannong 15’. In this study, cytological methods and genomic in situ hybridization (GISH) were employed to determine cytological stability and chromosome constitutions of the 10 octoploid Trititrigia accessions. Mitotic observation indicated that most plants of octoploid Trititrigia had 56 chromosomes and a few had 54 or 55 chromosomes. Chromosomes in most pollen mother cells of plants with 2n = 56 formed 28 bivalents, showing a high degree of cytogenetic stability, simultaneously, univalents, trivalents and tetravalents appeared occasionally at meiotic metaphase I. At meiosis anaphase I (PMC AI), most chromosomes segregated equally to the two poles except for several univalent chromosomes moving ahead in very few cells. Fourteen Th. intermedium chromosomes were observed to be added to the whole set of common wheat chromosomes in each octoploid Trititrigia, and the alien chromosome constitutions of the 10 octoploid Trititrigia accessions were 2St+8JS+2J+2J-St, 2St+8JS+4J, 2St+8JS+2J+2J-St, 2St+8JS+2J+2J-St, 2St+8JS+2J+2J-St, 6St+4JS+2J+2J-St, 4St+6JS+2J+2J-St, 2St+8JS+4J, 2St+8JS+4J, and 4St+6JS+4J. These alien chromosome constitutions were different from those reported in octoploid Trititrigia, suggesting that the 10 octoploid Trititrigia accessions are novel materials and might be valuable in wheat breeding programs.

Identification of Rice Chromosome Segment Substitution Line Z519 with Purple Sheath and Candidate Gene Analysis of PSH1

ZHOU Ke,LI Yan,WANG Shi-Ming,CUI Guo-Qing,YANG Zheng-Lin,HE Guang-Hua,LING Ying-Hua,ZHAO Fang-Ming

Acta Agron Sin. 2017, 43(07):  974-982.  doi:10.3724/SP.J.1006.2017.00974

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Anthocyanins as plant pigments are widely liked by people and play a very important role in food processing and hybrid purity identification. Here, a rice chromosome segment substitution line (CSSL) Z519 with purple sheath was identified deriving from recipient Nipponbare and donor R225. Z519 contained 16 substitution segments with 6.85 Mb of average length, which were distributed on 11 chromosomes of rice except the 10th chromosome. The bud sheath of Z519 began to appear the purple color stripes when it was about 3 mm long. Then the purple stripes displayed on sheaths, leaf margins, vascular bundles of stem and stigmas. While all parts of Nipponbare were green. Anthocyanin content in leaf sheath of Z519 was significantly higher than that of Nipponbare, whereas no significant difference was in flag leaf. Compared with Nipponbare, plant height of Z519 was significantly decreased, spikelets number and grain number of main panicle, and 1000-grain weight of Z519 were significantly increased. There was no significant difference between Z519 and Nipponbare in the other traits such as panicle number, main panicle length and seed-setting rate. Then, F2 recessive populations from the cross of Nipponbare and Z519 were used for genetic analysis and gene mapping of the purple sheath. The purple sheath in Z519 was controlled by a single dominant gene, named as PSH1, which was mapped on the chromosome 1 between InDel marker L03 and SSR marker L01 with the physical distance of 37.8 kb. By sequencing and gene-predicting in the region, Z519 had three bases (GTG) insertion in the GTG repeat area of the 238th?252th base in the first exon compared with Nipponbare, which resulted in increasing a Gly amino acid. Furthermore, the expression of LOC_Os01g45910 was obviously decreased in Z519 by qRT-PCR analysis. Thus, LOC_Os01g45910 was preliminary identified as the candidate gene of PSH1. The results lay a good foundation for studying molecular mechanisms of regulating anthocyanin by PSH1.

Developing of Specific Transcription Sequences P21461 and P33259 on D. villosum 6VS and Their Application of Molecular Markers in Identifying Wheat-D. villosum Breeding Materials with Powdery Mildew Resistance

LIU Chang,LI Shi-Jin,WANG Ke,YE Xing-Guo,LIN Zhi-Shan*

Acta Agron Sin. 2017, 43(07):  983-992.  doi:10.3724/SP.J.1006.2017.00983

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Dasypyrum villosum carries powdery mildew (PM) resistance gene Pm21 and PmV on its chromosome arms of 6V#2S and 6V#4S, respectively. The two resistant genes are co-segregated with exogenous chromosome arms in the offspring of hybrids between translocation lines and common wheat varieties. Developing polymorphic expression sequences to identify the two exogenous chromosomal arms is of great significance for their application in genetics and breeding, especially for 6V#4S chromosome, on which hereditary informations relatively lack. In this study, transcriptome of leaves of 6V#4S?6DL translocation line Pm97033 and common wheat line Wan7107 inoculated with Bgt was used as resources for sequences screening. As results, two unigenes of P21461 and P33259 from 6V#4S were identified by differential gene screening, synteny analysis, genomic DNA amplification and products sequencing of D. villosum accordingly. By using a pair of designed primer P461-5 based on P21461 sequence, it was found that there were 30 bp of InDel and 4 nt polymorphism between chromosomal arms of 6V#2S and 6V#4S. By the newly developed marker P461-5a, which retains the InDel polymorphism and truncates the product size amplified by P461-5, several wheat varieties and advanced lines with strong resistance to powdery mildew were identified to contain Pm21 or PmV. This marker showed potential application in discriminating D. villosum resources and assisted selection breeding for PM resistance in wheat. A marker P259-1 developed according to sequence of P33259 could specifically amplify a fragment from the wheat lines containing 6V#4S chromosome arm, but not amplify any fragment in the wheat lines containing 6V#2S?6AL translocation chromosome. Thereby, P259-1 can be used as a 6V#4S?6DL specific molecular marker in wheat backgrounds. The qRT-PCR assay showed that the expression of P21461 was not induced by PM. While transcriptional levels of P33259 increased about two times at 12 h and 24 h after inoculating the pathogens, suggesting that it might be involved in early interaction between Pm97033 and the pathogen.

Screening of Tobacco Genotypes with Tolerance to Low-Nitrogen and Analysis of Their Nitrogen Efficiency

ZHONG Si-Rong,CHEN Ren-Xiao,TAO Yao,GONG Si-Yu,HE Kuan-Xin,ZHANG Qi-Ming,ZHANG Shi-Chuan,LIU Qi-Yuan

Acta Agron Sin. 2017, 43(07):  993-1002.  doi:10.3724/SP.J.1006.2017.00993

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It is an effective way to screen tobacco genotypes with tolerance to low-nitrogen which increase nitrogen use efficiency and decreased nitrogen pollution. In this paper, 74 tobacco genotypes were treated with low nitrogen (0.5 mmol L–1) and normal nitrogen (5.0 mmol L–1) levels in hydroponics at seedlings stage, and evaluated and screened by using descriptive statistics, factor analysis and cluster analysis The variation coefficient of root volume, root biomass, stalk and leaf nitrogen accumulation, aboveground biomass were relatively large under low nitrogen and normal nitrogen conditions, with rang of 0.37–0.68 and 0.38–0.64, respectively. The principal components were similar for both treatments; the stalk and leaf nitrogen accumulation and aboveground biomass played a major role. According to heatmap cluster analysis and scatter diagram analysis, 15 genotypes with tolerance to low-nitrogen were screened out, accounting for 20.3% of the test materials, eight of which were low nitrogen high efficiency and normal nitrogen low efficiency genotypes, accounting for 53.3% of the low-nitrogen tolerant genotypes, six were low nitrogen low efficiency and normal nitrogen low efficiency genotypes, accounting for 40.0%, and one was low nitrogen high efficiency and normal nitrogen high efficiency, accounting for 0.7%. Eight low-nitrogen sensitive genotypes were screened out, among them six belonged to low nitrogen low efficiency and normal nitrogen high efficiency, accounting for 75.0%, two to low nitrogen low efficiency and normal nitrogen low efficiency, accounting for 25.0%. The study suggested that 14P9 was low-nitrogen tolerance and nitrogen high efficiency genotype, while Zhongyan 100 and K394 were low-nitrogen sensitive and nitrogen low efficiency genotypes.

QTL Mapping for Oil, Protein and Sesamin Contents in Seeds of White Sesame

WU Kun1,2,WU Wen-Xiong1,YANG Min-Min1,LIU Hong-Yan1,HAO Guo-Cun1,ZHAO Ying-Zhong1,*

Acta Agron Sin. 2017, 43(07):  1003-1011.  doi:10.3724/SP.J.1006.2017.01003

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Seed oil content, protein content and sesamin content are three important targets for sesame breeding. The objective of this study was to explore the genetic model and detect quantitative trait loci (QTLs) for three quality traits using a mapping population containing 224 recombinant inbred lines (RILs, F9). The three quality traits of seeds were measured by near infrared reflectance spectroscopy (NIRS) in three environments. Correlation analysis showed oil content was negatively correlated with protein content but positively correlated with sesamin content, whereas, protein content was negatively correlated with sesamin content. Using mixed composite interval mapping (MCIM) method, a total of eight QTLs distributed were detected for the three seed quality traits, with contribution ratio of QTL additive effect from 0.41% to 14.55%. While 13 QTLs were detected on nine LGs with multiple interval mapping (MIM), explaining 5.2% to 18.6% of the total phenotypic variation. Five QTLs were detected to be located on the same regions with MCIM and MIM, and two QTLs were detected in more than two environments. The Qoc-5 and Qsc-5 were located on the same region of LG5, both of which had positive additive effect, while the Qpc-5 was on the nearby region with negative additive effect. Similar results also existed on LG2 and LG1, which might be due to pleiotropism or closely linkage. Accordingly, the contents of oil and sesamin in seed can be improved together, while select protein content negatively in breeding.

Positive Regulation of CsbZIP4 Transcription Factor on Salt Stress Response in Transgenic Arabidopsis

CAO Hong-Li,WANG Lu,QIAN Wen-Jun,HAO Xin-Yuan,YANG Ya-Jun,WANG Xin-Chao

Acta Agron Sin. 2017, 43(07):  1012-1020.  doi:10.3724/SP.J.1006.2017.01012

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Basic region / leucine zipper (bZIP) transcription factors is a multi-functional protein family in eukaryotes, which is involved in various biological processes including seed maturation, light signaling regulation and stress response. According to sequence similarity and conserved motifs, the AtbZIPs are classified into 10 groups (A, B, C, D, E, F, G, H, I, and S). In this study, CsbZIP4 of C-group bZIP transcription factors was as an objective, the expression patterns of CsbZIP4 in response to abiotic stress in tea plants were investigated, and the salinity tolerance caused by CsbZIP4 overexpression in Arabidopsis was analyzed. The CsbZIP4 from tea plant leaves was up-regulated under 4°C, exogenous ABA, salinity and dehydration stresses, especially induction of salinity and dehydration stresses led to up-regulation of 2.9-fold and 2.2-fold, respectively. In roots, CsbZIP4 was down-regulated in response to cold, salinity and dehydration stresses, especially down-regulated by 2-fold under salinity stress. Under fluorescence microscope, it was indicated that CsbZIP4 was located in nucleus. Constitutive overexpression of CsbZIP4 in transgenic Arabidopsis lowered the plants’ sensitivity to exogenous ABA and salinity at germination stage. Moreover, CsbZIP4 overexpression lines exhibited higher salinity tolerance under 300 mmol L–1 NaCl conditions and higher SPAD values. AtSOS1, which is a salinity responsive gene, was strongly induced in overexpression lines. In conclusion, CsbZIP4 positively regulates salt stress response in Arabidopsis, and might be closely related to the tolerance to salinity stress in tea plant.

Cloning, Characteristics and Regulating Role in Thermotolerance of Heat Shock Transcription Factor (ZmHsf25) in Zea mays L.

ZHAO Li-Na,DUAN Shuo-Nan,ZHANG Hua-Ning,GUO Xiu-Lin,Guo-Liang

Acta Agron Sin. 2017, 43(07):  1021-1029.  doi:10.3724/SP.J.1006.2017.01021

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Heat shock transcription factors (Hsfs) are key components of signal transduction pathways involved in the activation of genes in response to heat shock stress in plants. There are at least 30 Hsf members in maize and seven of which belong to class B. In our previous work, we obtained ZmHsf06, which belongs to subclass A1, and investigated the characteristics of expression, subcellular localization, and regulating roles in thermotolerance and drought-stress tolerance of ZmHsf06. In the present study, ZmHsf25 was isolated from maize (Zea mays L.) young leaves treated by heat shock at 42°C for 1 h using homologous cloning methods. The sequencing analysis showed that the coding sequence (CDS) of ZmHsf25 was 957 bp and encoded a protein of 318 amino acids. The amino acid sequence analysis demonstrated that ZmHsf25 contained a DNA-binding domain (DBD), a nuclear localization signal (NLS) of KRLR peptide and a nuclear export signal (NES) of VLTLSV peptide. The identity of amino acid between ZmHsf25 and Sb060g025710 of sorghum was the highest, which was 92%. ZmHsf25 was expressed in multiple tissues and organs of maize, and transcription expression level of ZmHsf25 was the highest in pollens compared with root, stem, functional leaf, immature embryo and ear. qRT-PCR results showed that ZmHsf25 was up-regulated by 42°C heat shock in both leaves and roots. Under normal conditions, ZmHsf25 was down-regulated by both SA and H2O2, but significantly up-regulated by heat stress at 42°C. Through transient reporter assay with onion (Allium cepa L.) epidermal cells, we found that ZmHsf25 was localized in nuclei. ZmHsf25 overexpressed yeast showed stronger thermotolerance than the controls after heat shock (HS), though yeast thermotolerance was both decreased by HS. The results revealed that ZmHsf25 perhaps is one of downstream elements of SA signal pathway to play a key role in regulating the response to heat stress and pollen development. These results will provide a theoretical basis for analyzing biological characteristics and functions of maize Hsf members further.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of Cotton Stalk Returning on Soil Physical and Chemical Properties and Cotton Yield in Coastal Saline-Alkali Soil

QIN Du-Lin,WANG Shuang-Lei, LIU Yan-Hui,NIE Jun-Jun,ZHAO Na,MAO Li-Li,SONG Xian-Liang,Xue-Zhen

Acta Agron Sin. 2017, 43(07):  1030-1042.  doi:10.3724/SP.J.1006.2017.01030

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A continuous three-year field experiment of cotton-residue incorporation in coastal saline-alkali land was conducted, with two treatments: residue removal and residue incorporation. The successive cotton stalk returning significantly decreased soil bulk density in 0-30 cm soil layer and soil micro-aggregates with particle size <0.25 mm in 0-10 cm soil layer, while significantly increased the content of soil macro-aggregates with particle size >5 mm in 0-10 cm soil layer. Compared with the control (residue removal), the treatment of cotton residues incorporation significantly increased soil organic matter, nitrate nitrogen, ammonium nitrogen and available potassium by 13.45%, 18.57%, 22.80%, and 22.57%, respectively, while decreased soil available phosphorus and salinity by 18.29% and 16.59% at pre-sowing and each growth stage in 0-20 cm soil layer. Soil nitrate nitrogen and ammonium nitrogen were increased by 37.20% and 31.62% and soil salinity had a reduction of 19.06% after successive cotton stalk returning for three years in 20-40 cm soil layer, and also significantly increased by 38.26% and 24.83% in 40-60 cm soil layer. Successive cotton stalk returning significantly increased seed cotton yield by 11.57%, 19.01%, and 13.24% and lint yield by 18.56%, 19.78%, and 18.73% in three years, but not affected single boll weight and lint percentage.

Canopy Architecture, Physiological Characteristics and Assimilate Partitioning in Wheat Cultivars with 9000 kg hm?2 Yield Potential in Sichuan Basin

WU Xiao-Li,LI Chao-Su,TANG Yong-Lu,LI Jun,MA Xiao-Ling,LI Shi-Zhao,HUANG Ming-Bo

Acta Agron Sin. 2017, 43(07):  1043-1056.  doi:10.3724/SP.J.1006.2017.01043

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In contrast to the outstanding breeding progress of high-yield wheat in Sichuan Basin of China, the physiological basis of high-yield-potential cultivars is unclear due to seldom studies. In this study, a five-year field experiment (2011–2015) was carried out to compare the differences of canopy structure after anthesis, canopy apparent photosynthesis (CAP), chlorophyll content (SPAD), and dry matter partitioning between high-yield and normal-yield potential cultivars. Three typical high-yield and three normal-yield potential cultivars were selected, and the average yield of the high-yield potential cultivars (9422 and kg ha^-1) was 14.3% higher than that of the normal-yield potential cultivars owing to higher biomass or harvest index. Compared with the normal-yield potential cultivars, the high-yield potential cultivars had shorter and wider flag leaves (length-to-width ratio lower than 10) and showed obvious increases of basal and open angles of the topmost three leaves from early anthesis to mid-filling stage. From anthesis to late-filling stage, SPAD values of the topmost three leaves and CAP values at 0 and 20 days after anthesis were significantly higher in the high-yield potential cultivars than in the normal-yield potential cultivars, with the largest difference of CAP between 10:00 and 12:00 hour. In addition, the high-yield potential cultivars showed higher biomass proportion of stem and sheath at anthesis and higher (1–4 percentage points) biomass proportion of grain at maturity than the normal-yield potential cultivars. Grain yield was closely related to morphological and physiological parameters in wheat. For example, grain yield was positively correlated with basal angles of flag leaf (r = 0.947, P < 0.01) and the second leaf from top (r = 0.963, P < 0.01) at grain-filling stage and negatively correlated with leaf length-to-width ratios of flag leaf (r = -0.913, P < 0.01) and the second leaf from top (r = -0.911, P < 0.01). Grain yield was also positively correlated (P < 0.01) with SPAD values of the topmost three leaves (r = 0.75, 0.90, and 0.82), but negatively correlated with the proportion of spike rachis at maturity (r = ?0.956, P < 0.01). Our results indicate that moderate plant height, compact plant type, high SPAD and CAP values after anthesis, and proper dry matter partitioning are important factors in high-yielding physiology of wheat.

Effect of Potassium Application on Root Grow and Yield of Sweet Potato and Its Physiological Mechanism

WANG Shun-Yi,LI Huan,LIU Qing,SHI Yan-Xi*

Acta Agron Sin. 2017, 43(07):  1057-1066.  doi:10.3724/SP.J.1006.2017.01057

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The objective of this study was to investigate the physiological mechanism of potassium application on root growth and yield improvement in sweet potato. Two year field experiment was conducted with three potassium levels (0 kg ha–1, 75 kg ha–1, 150 kg ha–1, and 225 kg ha–1) to study the effects of potassium on root growth, 13C distribution, metabolic enzyme activity, photosynthetic characteristics and yield of sweet potato. Compared with CK, potassium treatments increased ETR 12.7% to 63.6%, Pn by 7.2% to 26.4%. Potassium application improved photosynthetic characteristics and accelerated the accumulation of photosynthate, providing material basis for root growth. While, potassium application was beneficial to the photosynthate products from shoots to roots, root 13C distribution amount increased by 10.6% to 66.2% (P<0.05). Then, potassium application by increasing sucrose synthase, sucrose phosphate synthase and adenosine diphosphate glucose pyrophosphorylase activities to accelerate the assimilation of carbon in roots, to improve the photosyntheate accumulation in roots, and to promote root differentiation and growth in sweet potato. In early growing stage, potassium application increased total root length by 13.6% to 22.8%, the average diameter of root increased by 11.3% to 51.9%, and significantly increased the differentiation from adventitious roots to fibrous roots and tuberous roots (P<0.05), which is beneficial to the early formation of effective tuber, ensureing the effective number of tubers per plant. Potassium treatments increased the root biomass and average tuber weight. Compared with CK, the potassium treatments increased yield by 5.8%, 24.3%, and 44.7% in 2014, and by 7.9%, 13.4%, and 22.8% in 2015.

Comparison of Photosynthetic Characteristics and Cluster Analysis in Potato Varieties (Lines)

ZHANG Gui-He,GUO Hua-Chun

Acta Agron Sin. 2017, 43(07):  1067-1076.  doi:10.3724/SP.J.1006.2017.01067

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The light response curve and CO₂ response curve of 17 potato varieties (lines) at the full-bloom stage were measured by using the LI-6400XT (a portable photosynthetic apparatus), and photosynthetic parameters were calculated fitting with a rectangular Hyperbola model. There were significant differences among different varieties (lines) in photosynthetic traits. Using principal factor analysis method, six photosynthetic parameters which had a significant impact on photosynthetic type of potato were selected when the cumulative contribution of variance accounted for 86.58%, including maximum net photosynthetic rate (Amax), light compensation point (Ic), dark respiration rate (Rd), initial efficiency of carboxylation (CE), leaf transpiration rate (Tr), and stomatal conductance (Cond.). According to the cluster and discriminant analysis of the six photosynthetic characteristics, 17 varieties (lines) of potato were divided into four categories. After comprehensive evaluation of the traits, five high photosynthetic efficiency varieties (lines) which belong to D class were picked out. These varieties showed higher net photosynthetic rate, stronger shade tolerance, lower consumption, moderate transpiration rate, higher stomatal conductance and medium initial carboxylation efficiency. They were Hezuo 88, D520, Dongnong1014III03, Qingshu 9, and 2010-11, which can be regarded as high photosynthetic efficiency breeding.

Yield and Water Use Efficiency of Winter Wheat in Response to Long-Term Application of Organic fertilizer from Different Nitrogen Resources Replacing Partial Chemical Nitrogen in Dry Land of Eastern Gansu Province

ZHANG Jian-Jun*,FAN Ting-Lu,ZHAO Gang,DANG Yi,WANG Lei,LI Shang-Zhong

Acta Agron Sin. 2017, 43(07):  1077-1086.  doi:10.3724/SP.J.1006.2017.01077

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The objective of this study was to find the possibility of organic fertilizers replacing partial chemical fertilizer continuous winter wheat cropping system through evaluating yield and water use efficiency (WUE). Using in winter wheat variety “Longjian 301”, we carried out a ten-year field experiment in the Loess Plateau of eastern Gansu province with two controls (no-fertilizer and chemical fertilizer) and three treatments of organic fertilizer (fermented organic fertilizer, farm manure, and wheat straw) replacing partial chemical fertilizer. The yield and water use efficacy of winter wheat varied greatly across years, with a direct effect of precipitation amount on them. Organic fertilizer replacing partial chemical fertilizer had positive effects on winter wheat yield and WUE, and the yield-increased rates were 53.1%–103.7%, 40.3%–79.3%, and 73.1%–94.8% over the no-fertilizer control and 6.6%–41.8%, 7.0%–36.8%, and ?2.9% to 9.3% compared with chemical fertilizer control in dry, normal and wet year, respectively. Among all treatments, the fermented organic fertilizer treatment showed the highest yield and WUE, as well as the largest yield-increased rate. In this treatment, the average yield of 10 years increased by 88.9% and 25.4% compared with no-fertilizer and the chemical fertilizer controls, respectively, and WUE and marginal water use efficiency were 10.8 kg mm?1 hm?2 and 1.03 kg m?3, respectively. Meanwhile, the yield components and plant physiological parameters in this treatment were also superior to those in other treatments. As a result, we suggest fermented organic fertilizer replacing partial chemical fertilizer in the semi-humid rain-fed area of eastern Gansu province, where annual precipitation is around 550 mm.

RESEARCH NOTES

QTL Mapping for Spike Traits of Wheat Using 90k Chip Technology

WU Bing-Jin,JIAN Jun-Tao,ZHANG De-Qiang,MA Wen-Jie,FENG Jie,CUI Zi-Xia,ZHANG Chuan-Liang,SUN Dao-Jie*

Acta Agron Sin. 2017, 43(07):  1087-1095.  doi:10.3724/SP.J.1006.2017.01087

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Spike traits are important to grain yield in wheat. Molecular markers associated with genes/QTLs controlling spike traits are highly valuable to marker-assisted breeding. A recombinant inbred line (F8) population derived from Zhou 8425B ? Xiaoyan 81 were evaluated in three environments, and QTLs for spike length, spikelet number per spike, sterile spikelet number, grain number per spike and thousand-grain weigh were mapped into a high-density genetic map built by 90k chip. A total of 71 QTLs were located on 19 chromosomes, and the phenotype variation explained (PVE) by a single locus ranged from 2.10% to 45.25%. Thirty-seven loci were considered as main-effect QTLs owing to the PVE larger than 10%. QTLs QSl.nafu-6A.2 for spike length, QSl.nafu-7A for spike length, QSsn.nafu-2A.1 for sterile spikelet number, QSsn.nafu-2D for sterile spikelet number and QGns.nafu-2B for grain number per spike were identified repeatedly in different environments with the LOD value higher than 10 and PVE larger than 20%. QSl.nafu-6A.2 for spike length, QGns.nafu-6A for grain number per spike and QTgw.nafu-6A for thousand-grain weight were mapped in a cluster on chromosome 6A and might be applicable in marker-assisted selection because they have been detected in multiple environments and close to the loci reported.

Construction of New Genetic Map and Identification of QTLs Related to Agronomic Traits in Mung Bean

WANG Jian-Hua,ZHANG Yao-Wen,CHENG Xu-Zhen,WANG Li-Xia

Acta Agron Sin. 2017, 43(07):  1096-1102.  doi:10.3724/SP.J.1006.2017.01096

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Two hundreds and eight individuals of F2 population, derived from a cross between two mung bean genotypes (Huaye 1 and Zijing 1) were used to construct genetic map, and to identify QTLs related to important agronomic traits. This genetic map contained 11 linkage groups with a total length of 1457.47 cM and an average interval of 15.34 cM. QTLs mapping was conducted for plant height, young stem color, main stem color, growth habit, podding habit, trilobate leaf shape and mature leaf color using composite interval mapping method. Only one QTL for each trait was detected including plant height, young stem color, main stem color and trilobate leaf shape, and with a contribution ranging from 8.49% to 66.64%. Three QTLs with high contribution rates from 60.32% to 80.36% were identified for the trait of pod habit in mung bean. Four QTLs related to mature leaf color showed at contribution rate from 69.06% to87.35%. There were 26 QTLs related to growth habit, the most of the tested QTLs, with a contribution rate each from 58.32% to 99.51%. The present QTLs for seven agronomic traits distributed on LG1, LG2, LG4, LG8, and LG10, respectively, could be used in molecular breeding based on marker-assisted selection in mung bean, and also lay a foundation for further study of the inheritance of these traits.