Table of Content

12 November 2016, Volume 42 Issue 11

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Genome-wide Identification of Acyl-CoA-Binding Protein (ACBP) Gene Family and Their Functional Analysis in Abiotic Stress Tolerance in Cotton

QIN Peng-Fei,SHANG Xiao-Guang,SONG Jian,GUO Wang-Zhen

Acta Agron Sin. 2016, 42(11):  1577-1591.  doi:10.3724/SP.J.1006.2016.01577

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Acyl-CoA-binding protein (ACBP) plays important roles in plant development, including normal growth, response to biotic/abiotic stress and membrane system repairing. However, the functions of ACBPs in cotton still remain largely unknown. Based on the G. hirsutum TM-1 genome database, we identified 21 ACBP genes and obtained their sequence information, chromosomal location. Phylogenetic analysis revealed that the 21 ACBP genes were classified into four groups. According to the nomenclature of A. thaliana homologous gene, the cotton ACBP genes were named as GhACBP1–GhACBP6 subclasses. Transcriptome data showed that the expression patterns of ACBP genes varied significantly in different cotton tissues. Further abiotic stresses treatment analysis showed that GhACBP1, GhACBP3, and GhACBP6 sub-class genes could be significantly induced by drought, salt, low temperature and high temperature treatments, while GhACBP4 and GhACBP5 sub-class genes could not. GhACBP3 and GhACBP6 could also be significantly induced by hydrogen peroxide (H2O2), salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA), and ethylene (ET). Virus induced gene silencing (VIGS) results exhibited that down-regulation of GhACBP3 and GhACBP6 sub-class genes would significantly reduce the plant tolerance to drought and salt stresses. Compared with the control, the GhACBP3 and GhACBP6 silencing plants demonstrated significantly reduced plant dry matter, decreased plant height, lower superoxide dismutase (SOD) and peroxidase (POD) activities, and

QTL Mapping for Ear Architectural Traits under Three Plant Densities in Maize

WANG Hui,LIANG Qian-Jin,HU Xiao-Jiao,LI Kun,HUANG Chang-Ling,WANG Qi,HE Wen-Zhao,WANG Hong-Wu*,LIU Zhi-Fang*

Acta Agron Sin. 2016, 42(11):  1592-1600.  doi:10.3724/SP.J.1006.2016.01592

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To identify genetic factors of ear architectural traits response to plant density, we developed a recombination inbred line (RIL) mapping population with 220 families from a cross between two maize inbred lines, Zheng 58 and HD568. The filed experiments were performed in 2014 and 2015 seasons of Beijing and Hainan. The ear architectural traits including ear length, ear diameter, ear row number and kernel number per row were evaluated under three plant densities in each environment. With the BLUP value estimated by SAS software, QTLs for ear architectural traits were detected by inclusive composite interval mapping (ICIM) using Windows QTL ICI-Mapping software. In total, 42 QTLs were detected under three plant densities, each QTL explained phenotypic variation ranging from 4.20% to 14.07%. One QTL related to ear row number on chromosome 2 was repeatedly detected under three plant densities. Four QTLs related to ear diameter, ear row number and kernel number per row were commonly detected under two plant densities, among them an ear row number QTL was located on chromosome 4 with explained 10.88% and 14.07% of phenotypic variance under plant density of 52 500 plants ha-1 and 67 500 plants ha-1. In addition, we found three QTLs for different ear architectural traits on chromosomes 2, 4 and 9 simultaneously. This study revealed the genetic mechanisms of ear architectural traits changed under different plant densities. The QTLs stably expressed under different plant densities can be applied in fine mapping and marker assisted selection in density tolerance breeding of maize.

TaPK-R1 Overexpressing Transgenic Wheat Lines Enhance ResistancetoSharp Eyespotand Freezing Stress

LUO Mei-Ying, RONG Wei, WEI Xue-Ning,YANG Kun,XU Hui-Jun, XUAN Wei-Yan, ZHANG Zeng-Yan

Acta Agron Sin. 2016, 42(11):  1601-1608.  doi:10.3724/SP.J.1006.2016.01601

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Sharp eyespot caused by Rhizoctonia cerealis is a soil-borne disease and freezing stress is one of the major abiotic stresses in wheat production. The object of this study was to improve wheat resistance to sharp eyespot and freezing using transgenic technique. The transformation vector pAHC25-MYC-TaPK-R1 expressing the wheat AGC protein kinase gene TaPK-R1 was constructed and transformed into the spring wheat Chinese cultivar Yangmai 20 through particle bombardment. The transformed T1 to T4 plants were subjected to PCR, RT-PCR, qRT-PCR, and Western blot analyses. Three transgenic wheat lines were generated and screened, in which the introduced TaPK-R1 transgene was inherited and expressed in higher level. After inoculation with R. cerealis virulent-isolate R0301 or WK207, these three TaPK-R1-overexpressing transgenic wheat lines displayed significant improved resistance to sharp eyespot. The infection types of these 3 transgenic lines in T1 to T4 generations were 1.16–2.11, and their disease indices were 23.20–42.10. At the same time, the infection types and disease indexes of the non-transformed wheat Yangmai 20 were 2.55–3.60 and 51.00–72.00, respectively. The three-leaf wheat seedlings were treated with ?9 ?C for 24 hours. Freezing tolerances of the three transgenic lines were dramatically improved, whose survival rates were 52%, 79%, and 96%, respectively, and significantly higher (P < 0.01) than that of the non-transformed Yangmai 20 (survival rate of 17%). Our results indicate that resistance/tolerance to sharp eyespot and freezing stress could be significantly enhanced in TaPK-R1 overexpressing transgenic wheat. The three transgenic lines may serve as potential resource in wheat breeding aiming at resistance improvement to sharp eyespot and freezing stress.

Construction and Genetic Evaluation of Chromosome Segment Substitution Linesin Tobacco(NicotianatabacumL.)

TONG Zhi-Jun, JIAO Fang-Chan, FANG Dun-Huang, CHEN Xue-Jun, WU Xing-Fu, ZENG Jian-Min, XIE He, ZHANG Yi-Han, XIAO Bing-Guang*

Acta Agron Sin. 2016, 42(11):  1609-1619.  doi:10.3724/SP.J.1006.2016.01609

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A set of chromosome segment substitution lines (CSSLs) of tobacco (Nicotiana tabacum L.) were first developed by molecular marker assisted selection (MAS) and successive backcrossing with Y3, the flue-cured tobacco germplasm with comprehensive traits as the recipient parent, and two common tobacco cultivars Beinhart1000-1 and K326 as the donor parents. The cigar tobacco cultivar Beinhart1000-1 carries a variety of resistance traits including black shank (race 0 and race 1) and brown spot resistance, while the flue-cured tobacco K326 is a commercial cultivar with high quality. In 256 CSSLs, a total of 377 substituted segments derived from donor Beinhart1000-1 and K326 with genetic background of Y3 distributed on 24 linkage groups. Each CSSL contained only 1–5 substituted segments and the length of substituted segments ranged from 0.05 to 36.88 cM with an average of 7.75 cM. The total length of the overlapped substituted segments was 2922.57 cM, which was 2.61 times of the whole tobacco genome length. And the CSSLs covered length was 1114.32 cM, with a covered ratio of 99.45% in the recurrent tobacco genome. The CSSLs constructed in this study are excellent genetic materials for gene mapping, QTL analysis of complicated traits, and developing varieties by marker assisted selection in Nicotiana tabacum L.

Mapping QTL Protein and Oil Contents Using Population from Four-way Recombinant Inbred Lines for Soybean (Glycine max L. Merr.)

NING Hai-Long,BAI Xue-Lian,LI Wen-Bin,XUE Hong,ZHUANG Xu,LI Wen-Xia,LIU Chun-Yan

Acta Agron Sin. 2016, 42(11):  1620-1628.  doi:10.3724/SP.J.1006.2016.01620

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Increasing protein content (PC) and oil content (OC) are main goals in soybean improvement, so mapping quantitative trait locus (QTL) and mining elite alleles underlying PC and OC are of importance for molecular design breeding in soybean. In this research a four-way recombinant inbred line population derived from double cross (Kenf 14 × Kenf 15) × (Hein 48 × Kenf 19) with 204 lines was used to analyze the data of PC and OC from the field experiments in eight environments across Harbin and Keshan in 2013, 2014, and 2015 by interval map method based on a linkage map constructed in previous research. The 29 PC QTLs and 39 OC QTLs were detected from eight planting environments. Among the twenty-nine PC QTLs, five were detected across over two environments, which distributed on six linkage groups, i.e. A1, D2, J, N and O, with explained phenotypic variation (PVE) ranging from 7.65% to 20.08%. Four of them, i.e. qPC-A1-1, qPC-D2-1, qPC-J-1, and qPC-O-2, showed PVE over 10%. Of the thirty-nine OC QTLs, ten were found in more than two environments, which were located on linkage groups A1, A2, B1, D1b, G, I, J, and N with PVE ranging from 7.30% to 25.68%. Four out of the ten QTLs that included qOC-A2-1, qOC-B1-1, qOC-G-1, and qOC-J-1 had PVE above 10%.

Cloning and Functional Analysis of Peanut Δ⁹-Stearoyl-Acyl Carrier Protein Desaturase Promoter

SHI Lei, MIAO Li-Juan, QI Fei-Yan, ZHANG Zhong-Xin, GAO Wei, SUN Zi-Qi, HUANG Bing-Yan, DONG Wen-Zhao, TANG Feng-Shou, and ZHANG Xin-You*

Acta Agron Sin. 2016, 42(11):  1629-1637. 

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The Δ9-stearoyl-acyl carrier protein desaturase (SAD) plays key roles in determining the ratio of saturated to unsaturated fatty acids in higher plants. The 720 bp 5′ flanking sequence of peanut SAD (AhSAD) gene was isolated from the genomic DNA of peanut cultivar Yuhua 9326 by nested PCR using genomic walking method. The fragment of 5′ UTR was obtained using 5′ RACE (Rapid Amplification of cDNA End), confirming that the 720 bp 5′ flanking sequence is promoter fragment based on sequence alignments. Bioinformatics analysis indicated that AhSAD promoter contained several light, hormone responsive elements and enhancer-like elements as well as CAAT box and TATA box. To study the function of this promoter, we constructed a binary expression vector pBI-PAhSAD by replacing CaMV35S promoter of pBI121 with the AhSAD promoter, which was introduced into Arabidopsis and transiently expressed in peanut, respectively, by Agrobacterium-mediated transformation. Histochemical staining analysis showed that the GUS gene mainly expressed in roots, stem, leaves, cotyledon and peanut pegs. The histochemical staining was observed in peanut whole leaves, while only in Arabidopsis veins of cauline leaves.

Analysisof Blast Resistance Genesin Japonica Variety Jijing 809

ZHU Ya-Jun1,??, SUN Qiang2,??, WANG Jin-Ming2, CHEN Kai1, FENG Bo1, FANG Ya-Jie1, LIN Xiu-Yun2,*, and XU Jian-Long1,3,*

Acta Agron Sin. 2016, 42(11):  1638-1646. 

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Blast is one of the most hazardous diseases in rice production. Planting resistance variety is an effective measure to control the disease. In this study, a backcross population derived from two parents, Jijing 88 and 93072, was selected to identify blast resistance genes using bulked extremes and recessive class under artificial inoculation and further to deduce the composition of resistance genes in Jijing 809 developed from Jijing 88 and 93072. Four major resistance genes including Pi-2(t), Pi-7-1(t), Pi-7-2(t), and Pi-11(t) were responsible for segregation of resistance to the strong virulent strain GD9-1, and only one resistance gene Pi-2(t) for segregation of resistance to the weak virulent strain GD19-1. Among them, Pi-2(t) was effective to the two strains. The favorable alleles at all loci were from 93072 except for the allele at Pi-2(t) from Jijing 88. By comparative mapping, Pi-2(t) was deduced to be allelic to Pi-b, and Pi-11(t) to Pi-47(t) or Pik, whereas Pi-7-1(t) and Pi-7-2(t) were the two newly identified resistant genes, having linkages with RM21260 and RM8037 at 0.11 and 6.97 cM, respectively. SSR markers tight by linked with the four resistance genes mentioned above and a set of 55K gene chip developed from re-sequenced data of 3K rice germplasm were used to compare and identify genotypes of Jijing 809 at the above resistant loci with the two parents. It was indicated that two pairs of resistant genes, Pi-2(t) and Pi-11(t), in Jijing 809 were from the recurrent parent Jijing 88 and the donor parent 93072, respectively, which reasonably explained that Jijing 809 had much better blast resistance than Jijing 88. It was discussed how to pyramid different known major resistant genes, especially to make full use of the ‘defeated’ resistance gene in the original resistant variety to improve blast resistance of rice.

RNAi-mediated SMV-P3 Silencing Increases Soybean Resistance to Soybean Mosaic Virus

YANG Xiang-Dong,NIU Lu,ZHANG Wei,YANG Jing,DU Qian,XING Guo-Jie,GUO Dong-Quan,LI Qi-Yun,DONG Ying-Shan

Acta Agron Sin. 2016, 42(11):  1647-1655.  doi:10.3724/SP.J.1006.2016.01647

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Soybean mosaic virus (SMV) is one of the most important diseases in major soybean production areas and has severe effects on soybean production and seed quality in China. Breeding disease-resistant varieties is the most economical and effective strategy to prevent and control SMV. In this study, RNAi fragments of the gene encoding P3 protein, which is involved in SMV mobility and affecting host range, were introduced into soybean by plant-mediated RNA interference (RNAi) techniques to explore the influence of RNAi-mediated SMV-P3 silencing on soybean SMV resistance. Southern blot analysis revealed that exogenous RNAi fragments were integrated into the soybean genome at low copy numbers (1–4). T1–T3 generation transgenic soybeans were sprayed with herbicide and inserted fragments were examined using PCR. The results indicated that T-DNA insertion fragments could be stably inherited between generations of transgenic soybean. Inoculation of T2 and T3 generation transgenic soybeans with SMV suggested that transgenic soybeans exhibited significantly higher resistance to the prevailing SMV strain, SC-3, in major soybean production areas than the non-transgenic control varieties Williams 82 and SN9. The disease index was reduced by 4.37%-18.51%. Further, the resistance could be stably inherited. In conclusion, RNAi-mediated SMV-P3 silencing can significantly increase the SMV resistance of transgenic soybeans.

Cloning and Expression Analysis of ZmMADS-RIN Gene for Regulating the Kernel Development of Maize

XIA Xue, MA Chen-Yu, BAI Qing-He, FENG Yuan-Yuan, WANG Shun-You, WANG Xi, ZHOU Qing-Li, and XI Zhang-Ying*

Acta Agron Sin. 2016, 42(11):  1656-1665.  doi:10.3724/SP.J.1006.2016.01656

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Kernel development is the most important character of maize. In this study, a maize gene named ZmMADS-RIN encoding MADS-box protein relating to kernel development was isolated. The full length cDNA of ZmMADS-RIN is 859 bp, and it contains an open reading frame (ORF) with 768 nucleotides and encodes 255 amino acid residues. The variable analysis of ZmMADS-RIN in coding region showed that six nucleotides and three amino acid residues were different between Zheng 58 and B73. Bioinformatics analyses showed that ZmMADS-RIN was a hydrophilic protein with a molecular weight of 29.23 kD, a theoretical isoelectric point of 8.84, and five phosphorylation sites, but signal peptide sequence and transmembrane domain were not found. The secondary structure of ZmMADS-RIN protein contained 50.20% of alpha helix, 27.45% of random coil, 14.51% of extended strand and 7.84% of beta turn. ZmMADS-RIN protein was tested to be a typical MIKC-type protein localized in nucleus with highly conserved MADS domain, relatively conserved K domain, less weakly conserved I domain and most variable C domain. Phylogenetic analysis indicated that ZmMADS-RIN protein belongs to the same branch of AGL6, and shows high similarity of 89% to OsMADS6 protein from Oryza sativa. RT-PCR results showed that ZmMADS-RIN expressed in kernel specially, and not in root or leaf during different phases. In addition, qRT-PCR results indicated that the expression of ZmMADS-RIN increased continually from zero day to 20 days after pollination, and reached the highest level at the 20th day, then decreased significantly. And it could not be detected during 30th?40th days. These results demonstrated that ZmMADS-RIN might be associated with the regulation of developing kernel in maize.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effect of Nitrogen Application Regime on Yield,Nitrogen Absorptionand Utilization of Mechanical Pot-Seedling Transplanting Rice with GoodT aste Quality

HU Qun1, XIA Min1, ZHANG Hong-Cheng1,*, CAO Li-Qiang1, GUO Bao-Wei1, WEI Hai-Yan1, CHEN Hou-Cun2, DAI Qi-Gen1, HUO Zhong-Yang1, XU Ke1, LIN Chang-Ming2, and HAN Bao-Fu3

Acta Agron Sin. 2016, 42(11):  1666-1676. 

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In recent years, the planting area of good taste quality rice in the Yangtze River region is continuously expanded. With developing the new matching technology of mechanical pot-seedling transplanting rice, the yield and efficiency of good taste quality rice were increased significantly. Nitrogen fertilizer plays a major role in rice production. Two representative rice cultivars with good taste quality grown in Jiangsu, named Nanjing9108 and Nanjing5055, were adopted in this study. The total amount of nitrogen applied in each treatment was 270 kg ha-1 with different ratio of basal-tillering-fertilizer to panicle-fertilizer, including 10:0, 9:1, 8:2, 7:3, 6:4, 5:5, and 4:6. The effects of the nitrogen application strategies on yield and its components, stems and tillers dynamic, leaf area index(LAI), dry matter accumulation, and nitrogen use efficiency of rice were studied and the best method of nitrogen application was also accessed. It was found that the treatment with the ratio of basal-tillering-fertilizer to panicle-fertilizer of 6:4 had the highest yield, due to its higher spikelets per panicle based on more and stable panicle number, higher seed setting rate and 1000-gain weight than these of other treatments. The population number of stems and tillers gradually reduced with the ratio of basal-tillering fertilizer decreased and gently decreased after jointing stage in the treatments with more panicle-fertilizer. The percentage of productive tillers decreased with the ratio of panicle-fertilizer increased. During the middle and late growth stages, the treatment of 6:4 had significantly larger LAI and higher dry matter accumulation. The treatment of 6:4 had a litter nitrogen accumulation before jointing, but higher nitrogen accumulation after jointing and higher total nitrogen accumulation at mature stage than other treatments. Apparent nitrogen use efficiency, physiological nitrogen use efficiency, agronomic nitrogen use efficiency and partial factor productivity of applied nitrogen were higher in treatment of 6:4 than in other treatments too. In general, the treatment with the ratio of basal-tillering-fertilizer to panicle-fertilizer of 6:4 is conducive to get suitable panicle number, large spike, increased filled-grain percentage and 1000-grain weight, coordinative yield components and optimized population quality, which is the best nitrogen application regime for mechanical pot-seedling transplanting rice with good taste quality to achieve mutual unity of high yield and high nitrogen use efficiency.

Nitrogen-Reducingand Suitable SoilMoisture Enhance Photosyn thetic Potential of FlagLeaf and Grain Yieldin Winter Wheat

ZHOU Su-Mei, ZHANG Ke-Ke, ZHANG Man, LI Lei, ZHANG Chun-Li, YIN Jun*, and HE De-Xian

Acta Agron Sin. 2016, 42(11):  1677-1688.  doi:10.3724/SP.J.1006.2016.01677

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This study aimed at seeking a possibility of reducing nitrogen (N) fertilizer input on getting high yield in wheat (Triticum aestivum L.) production in Huang-Huai Valley region. A field experiment was carried out with treatments of three soil moistures and three N application levels, to measure light-response curve parameters of flag leaf, water use efficiency and yield-component traits in the 2013–2014 and 2014–2015 growing seasons. The soil moisture treatments included no irrigation (W1), medium irrigation to 70?5% of soil relative moisture after jointing stage (W2), and well-irrigation to 80±5% of soil relative moisture after jointing stage (W3). The N application rates were 0 (N1), 195 (N2), and 270 kg ha?1 (N3). Under W1 and W2 conditions, N2 treatment showed greater increases in net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) of flag leaf and greater reduction rate of intercellular CO2 concentration (Ci) than N1 and N3 treatments. Under W3 treatments, N2 and N3 treatments had similar changing trend of light response curves. N2W2 was the most superior treatment in photosynthesis at anthesis stage, with the maximum Pn of 33.20 μmol CO2 m?2 s?1 and the light saturation point (LSP) of 1507.4 μmol m?2 s?1, which were 21.4% and 9.5% higher than these averages of other treatments, respectively. In addition, N2W2 showed the lowest light compensation point, indicating its high photosynthetic potential. As a result, N2W2 had the largest kernal number and the highest thousand-grain weight across two years, with significant difference than other treatments (P < 0.01). The grain yield of N2W2 was more than 9500 kg ha?1, and the water use efficiency was 18.8% higher than that of other treatments under W2 and W3 conditions. These results suggest that reducing N application from 270 to 195 kg ha?1 under suitable soil moisture (medium irrigation) may increase wheat yield by enhancing the photosynthetic potential of flag leaf, which is a good management of irrigation and fertilizer for high yield and high N use efficiency in Huang-Huai Valley wheat region.

Effect of Returning Methods of Maize Straw and Nitrogen Treatments on Soil Physicochemical Property and Yield of Winter Wheat

PANG Dang-Wei, CHEN Jin, TANG Yu-Hai, YIN Yan-Ping, YANG Dong-Qing, CUI Zheng-Yong, ZHENG Meng-Jing, LI Yong, and WANG Zhen-Lin*

Acta Agron Sin. 2016, 42(11):  1689-1699. 

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The objective of this study was to understand the effect of continuous rotary tillage on soil tilth and wheat yield under straw-return and non-straw return conditions. A three -year field experiment from October 2012 to June 2015 was conducted with three tillage patterns (three-year rotary tillage without maize straw return, RT; three-year rotary tillage with maize straw return, RTS; and two-year rotary tillage plus one-year deep tillage with maize straw returning, RTS-DTS.) and four nitrogen application levels (165 kg ha-1, N165; 225 kg ha-1, N225; 300 kg ha-1, N300; 360 kg ha-1, N360). Compared with rotary tillage, deep tillage facilitated decomposition of the maize straw and high N level accelerated the decomposition speed. Under non-straw-return condition, continuous rotary tillage reduced the organic matter content in 0–30 cm soil layer, leading to increased bulk density and decreased soil porosity. Under straw-return condition, continuous rotary tillage increased the organic matter content in 0–10 cm soil layer and soil porosity and decreased bulk density. Moreover, RTS-DTS showed positive effects on tilth soil structure. For example, compared with RTS, RTS-DTS had the effect on increasing organic matter content in 10–30 cm soil layer, decreasing bulk density in 0–20 cm soil layer, and increasing the total porosity in 0–20 cm soil layer and capillary porosity in 10–30 cm soil layer. Three-year rotary tillage resulted in yield decline of wheat, particularly under non-straw return condition. Grain yield of RT in the third year was 5.0%–8.7% more than that in the first year. Although the yield of RTS was 7.3%–8.9% higher than that of RT, it also showed obvious decline in the third year. Compared with RTS, RTS-DTS showed great improvement in yield and yield components, with the increase of 14.5% in spike number, 5.7% in grain number per spike, and 7.6% in final yield. Under maize straw return condition, soil physical property was improved with the increase of N level. However, the final yield in treatments of N225, N300, and N360 was not significantly different. Our results suggest that RTS-DTS plus maize straw return with N application rate of 225 kg ha?1 is a high-yield and high-efficient cultivation pattern in Shandong province.

Drought Resistance of Wheat NILs with Different Cuticular Wax Contents in Flag Leaf

XU Wen,SHEN Hao,GUO Jun,YU Xiao-Cong,LI Xiang,YANG Yan-Hui,MA Xiao,ZHAO Shi-Jie,SONG Jian-Min

Acta Agron Sin. 2016, 42(11):  1700-1707.  doi:10.3724/SP.J.1006.2016.01700

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The relationship of flag leaf cuticular wax content with leaf water potential, excised-leaf water loss, leaf photosynthesis characteristics and wheat yield under drought stress were analyzed in 2013–2014 and 2014–2015 wheat seasons using four wheat nearly isogenetic lines (NILs) differing in cuticular wax content in flag leaf. Under drought stress condition, the average flag leaf cuticular wax content of the high-wax NILs (15.15 mg g?1) was 79.8% higher than that of the low-wax NILs (8.43 mg g?1). Compared with the low-wax NILs, the high-wax NILs showed significantly higher water potential in flag leaf and lower water loss rate (P< 0.05). In response to drought stress, photosynthetic rate (Pn) and Fv/Fm of flag leaf declined in both types of NILs, however, the decrease percentages were lower in the high-wax NILs (7.5% and 3.4%, respectively) than in the low-wax NILs (9.8% and 5.8%, respectively). As a result, the average yield of the high-wax NILs was 3.7% higher than that of the low-wax NILs, and the drought tolerance (TOL) and stress susceptible index (SSI) of the high-wax NILs were significantly less than those of the low-wax NILs (P< 0.05). These results indicate that cuticular wax content in flag leaf is closely related to drought tolerance and can be used as a physiological indicator of drought resistance in wheat selection.

Effect of Different Seeding and Transplanting Dates on Tillering Characteristics of Super Indica Hybrid Rice with Mechanized Seeding and Planting and Its Relationships with Meteorological Factors

ZHONG Xiao-Yuan,ZHAO Min,LI Jun-Jie,CHEN Duo,TIAN Qing-Lan,Wang Li,HUANG Guang-Zhong,REN Wan-Jun

Acta Agron Sin. 2016, 42(11):  1708-1720. 

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In order to explore tillering characteristics and its relationships with meteorological factors in super indica hybrid rice with mechanized seeding and planting with different seeding and transplanting dates, a split plot field experiment was conducted using super indica hybrid rice F you 498 and Yixiangyou 2115 with seedling age of 30 d and treatments of five seeding dates including March 21 (S1), March 31 (S2), April 10 (S3), April 20 (S4), April 30 (S5), and five transplanting dates including April 21, May 1, May 11, May 21, and May 31. Rice yield was significantly different under different seeding and transplanting dates, and decreased with delaying sowing dates. Yield of rice seeded on March 21 was the highest ,while that on April 30 was the lowest. The main stem contribution to yield was (S1–S4) < S5. The total contribution of primary tillers and secondary tillers group to yield was (S1–S4) > S5. Leaf 3 to leaf 6 with seeding date on S1, and leaves 3 to 5 from S2 to S5 were the superior leaf positions. Leaf positions of tiller emerging and earbearing tended to centralize with delaying sowing and transplanting dates. Primary tillers of F you 498 emerged mainly from 3/0 to 7/0 when seeding from S1 to S4, while emerged mainly from 3/0 to 6/0 when seeding on S5. Primary tillers of Yixiangyou 2115 emerged mainly from 3/0 to 7/0 when seeding on S1, while emerged mainly from 3/0 to 6/0 when seeding from S2 to S5. Primary tillers earbeared mainly from 3/0 to 6/0 when seeding on S1, while that was mainly from 3/0 to 5/0 when seeding from S2 to S5. Secondary tillers emerged and earbeared mainly from leaf 3 to leaf 4 on main stem. Primary and secondary tillers emerging rate was significantly negatively correlated with average relative humidity, while significantly positively correlated with average diurnal temperature range, accumulated temperature and average sunshine hours at tillering stage. The primary tiller earbearing rate was significantly negatively correlated with average relative humidity and average temperature at tillering stage, while significantly positively correlated with average diurnal temperature range at tillering stage, while significantly negatively correlated with average relative humidity at inflorescence differentiation stage, while significantly positively correlated with average sunshine hours. In comprehensive view, planting before May 11 will be more beneficial to higher yield, planting before May 21 will be in favour of stable yield, while planting after May 21 will decrease yield of rice in Chengdu plain.

RESEARCH NOTES

AWheat DELLA Gain-of-Function Mutant Aibian 1 Promotes Seedling Salt Tolerance

WANG Run-Qing1,2,**, FAN Xiao-Cong2,3**, SONG Mei-Fang2,4, XIAO Yang5, GUO Lin2, MENG Fan-Hua2,

Acta Agron Sin. 2016, 42(11):  1721-1726.  doi:10.3724/SP.J.1006.2016.01700

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DELLA proteins are negative regulators in GA signal pathway. DELLA protein is able to response to various environmental signals and plays an important role in plant resistance to biotic and abiotic stresses. The DELLA gain-of-function mutant Aibian 1 has been widely applied in wheat breeding for dwarfness, but its tolerance to salt is unclear. In this study, Aibian 1 was compared with Chinese Spring, Jing 411, and Aiganzao in salt tolerance using Hoagland’s hydroponic culture with 200 mmol L?1 NaCl. Total chlorophyll content, relative water content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were measured to evaluate the ability of salt tolerance. Immunoblot assay was employed to assess the DELLA protein abundance in wheat seedlings. After seven-day NaCl treatment, Aibian 1 showed no clear withering leaves, whereas the other three cultivars displayed obviously wilting and yellowing leaves. Among the four cultivars, Aibian 1 had the least loss on chlorophyll content and relative water content, the highest SOD activity, and the lowest levels of MDA content after salt treatment. Immunoblot assay indicated the highest accumulation of DELLA protein in Aibian 1 among the four cultivars. Thus, we consider the high level of DELLA protein is closely related to salt tolerance in Aibian 1.

Compensation Response of Drip-Irrigated Sugar Beets (Beta vulgaris L.) to Different Water Deficits during Storage Root Development

LI Yang-Yang,FEI Cong,CUI Jing,WANG Kai-Yong,MA Fu-Yu,FAN Hua

Acta Agron Sin. 2016, 42(11):  1727-1732.  doi: 10.3724/SP.J.1006.2016.01727

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The objective of this experiment was to investigate the compensation response of drip-irrigated sugar beets under drought stress and rewatering during storage root development. The experiment at treatments were field capacity of 70% (T1), 50% (T2), and 30% (T3). The yield, agronomic characteristics, and physical and chemical properties of the beet roots were measured. The sugar yield and technological sugar yield in T3 treatment were 51.7, 17.6% and 48.7%, 7.7% more than these in T1 and T2 treatments, respectively. At one day after rewatering, electrical conductivity, proline content, POD activity were significantly greater in T2 and T3 treatments than in T3 treatment during storage root development. Principal component analysis showed that a regulation system consisted of membrance permeability, antioxidant enzyme activity, osmotic adjustment and agronomic characteristics resisting drought stress, among which soluble sugar content can not be used as an indicator of drought resistance indentification of sugar beet during the devevelopment of sugar beet storage roots. Therefore, supplemental irrigation should be carried out promptly when the soil water content drops to 30% of field capacity during storage root development, which is beneficial to increase the sugar content and do not affect the growth of sugar beet.