Table of Content

12 June 2016, Volume 42 Issue 06

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Identification and Mapping of a Hybrid Sterility Gene between 9311 and Nipponbare

ZHANG Hong-Gen**,ZHANG Li-Jia**,SUN Yi-Biao,SI Hua,LIU Qiao-Quan,TANG Shu-Zhu*,GU Ming-Hong

Acta Agron Sin. 2016, 42(06):  787-794.  doi:10.3724/SP.J.1006.2016.00787

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Exploitation of subspecific heterosis is an effective method to improve rice yield by overcoming hybrid sterility between subspecies. In this study, F₁ plants of the cross between Nipponbare and T9424, a line from a set of chromosome segment substitution lines with Nipponbare background as recipient and 9311 as donor, showed the decreasing spikelet and pollen fertility compared with the two parents, indicating that there was the incompatibility between the parents. Three substituted chromosome segments on chromosome 1, 4, and 5, respectively, were identified by whole genome re-sequencing of T9424. Analysis of the genotypes and spikelet fertility of plants in Nipponbare/T9424 F₂ population indicated that hybrid sterility gene between T9424 and Nipponbare was located on chromosome 5. A total of 790 plants were then used for mapping the hybrid sterility gene, and the target gene was mapped to a candidate region with the physical distance of 110 kb between PSM8 and A14 on chromosome 5. The hybrid sterility gene, named S39(t) temporarily, controlled partial abortion of both pollen grains and embryo-sac of Nipponbare/T9424 F₁ plants. These results are useful for deepening understanding of the phenomenon of hybrid sterility, and lay the groundwork for the gene cloning and its use in breeding.

Genome-Wide Analysis of TaNBS Resistance Genes and Development of Chromosome 2AL-specific NBS-SSR Markers in Wheat

QIAO Lin-Yi,CHANG Jian-Zhong,GUO Hui-Juan,GAO Jian-Gang,ZHENG Jun,CHANG Zhi-Jian

Acta Agron Sin. 2016, 42(06):  795-802.  doi:10.3724/SP.J.1006.2016.00795

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Nucleotide binding site (NBS)-encoding genes are the most important resistance genes (R genes) in plant kingdom. In this study, 2406 full-length NBS protein sequences, of which single protein varies from 48 aa to 2272 aa, were identified from wheat (Triticum aestivum L.) genome using bioinformatic method. These TaNBSs were divided into four categories, including N, CN, NL and CNL, according to whether the NBS domains connect CC or LRR domains at both ends. Diagnosis results showed that 1203 of all the scaffolds with TaNBS contained 2177 simple sequence repeats (SSR) loci, 73.5% of which were dinucleotide repeat sites. Based on the NBS-SSR loci on chromosome 2AL in wheat, we developed 51 molecular markers , and 39 of them (76.5%) were confirmed as chromosome specific markers using Chinese Spring nulli-tetrasomic and ditelosomic lines. Furthermore, 24 2AL-specific NBS-SSR markers showed polymorphism between resistant material Khapli carried Pm4a on chromosome 2AL and susceptible material Chancellor. Finally, three 2AL-specific NBS-SSR markers, Sxaas_2AL22, Sxaas_2AL39, and Sxaas_2AL46, were probably linked to Pm4a gene based on genetic linkage test using Pm4a-NILs (Khapli/8*Cc). These chromosome specific 2AL-NBS-SSR markers can be used to locate novel R genes or screen the candidate sequences for known R genes on chromosome 2AL.

Quality of Major WheatCultivars Grown in Sichuan Province in Recent Decade

LI Chao-Su,WU Xiao-Li,TANG Yong-Lu,YANG Wu-Yun,WU Yuan-Qi,WU Chun,MA Xiao-Ling,LI Shizhao

Acta Agron Sin. 2016, 42(06):  803-812.  doi:10.3724/SP.J.1006.2016.00803

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Quality improvement is one of the major targets in winter wheat breedingin Southwest China in the past two decades.This study aimed at understanding the quality of the main varietiesreleased in Sichuan province, especially evaluatingthe quality and the breeding value ofsynthetic hexaploid wheat (SHW).In multi-environment trial from 2011 to 2013 (location × year), we evaluated the grain protein content (GPC), grain germination index (GI), falling number (FN), wet gluten content (WGC), sedimentation value (SDS), flour yield (FY), farinograph parameters, and Rapid Visco Analyzer (RVA) parameters of 10wheatcommercial cultivars. Theresults showed thatgenotype, environment, and genotype × environment interaction had significant effect on all quality parameters tested. The effect of environment was greater than that of genotype in most traits related to protein quantity and quality; whereas, the genotypic effect was greater than environmental effect in starch quality traits including FN and RVA parameters.In the 10 cultivars tested, the ranges of quality parameters were GPC 11.7–14.0%, WGC 22.0–29.3%, SDS 21.4–35.1 mL, FN 147–363 s, dough stability time1.7–12.1 min,andpeak viscosity1056–2670 cP. Chuanmai 104, a SHW cultivar with yield level of 9000 kg ha^-1,showed the best quality with SDS of 30.3mL, FN of 325s, dough stability time of 9.8min, and final viscosity of 2796cP. In contrast, Mianmai 367 showed the worst quality with SDSof 24.6 mL, FN of 147 s, dough stability time of 2.2 min, and final viscosity of 827 cP.Besides, germination index (GI) also varied significantly among cultivars. The mean GI of cultivars at physiological maturity stage was 0.31, ranging from 0.06 to 0.76. Chuanmai 104 had the lowest GI value. Our results suggest great potential for quality improvement of Southwest winter wheat, and Chuanmai 104 can be used as a promising parent in breeding programs.

Phenotypic Analysis and Gene Mapping of degenerated hull 3 (dh3) Mutant in Rice (Oryza sativa L.)

LONG Jue-Chen,ZHUANG Hui,CHEN Huan,WANG Ling,SHEN Ya-Lin,ZENG Xiao-Qin,CUI Xin-Yun,SANG Xian-Chun,HE Guang-Hua,LI Yun-Feng*

Acta Agron Sin. 2016, 42(06):  813-819.  doi:10.3724/SP.J.1006.2016.00813

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The floral organ development directly influences the yield and quality of rice. In this study, we reported a mutant degenerated hull 3 (dh3), derived from ethylmethane sulfonate (EMS)-treated Jinhui10 (Oryza sativa L. ssp. indica). The manifestation of dh3 mutant was degradation and narrowing in lemma and palea, losting the ability of close-up. In some seriously mutated florets, the lemma even degenerated in an awn-like shape, the margin region of palea and lodicules became narrow, even fused. Genetic analysis indicated that the dh3 character is controlled by a recessive gene. By using 356 F₂ mutants derived from a cross between sterile line Xinong 1A and dh3, DH3 was mapped between SSR markers RM27706 and RM27709 on chromosome 12 in rice, with a physical distance of 44.72 kb. There is no report of known functional gene in this zone. The results will shed light on the future clone and function analysis of DH3 gene.

Mapping QTLs For Wheat Panicle Traits with High Density SNP Genetic Map

LIU Kai,DENG Zhi-Ying,LI Qing-Fang,ZHANG Ying,SUN Cai-Ling,TIAN Ji-Chun*,CHEN Jian-Sheng*

Acta Agron Sin. 2016, 42(06):  820-831.  doi:10.3724/SP.J.1006.2016.00820

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Panicle traits of wheat are closely correlated between each other,of them grain number per spike and 1000-grain weight are important components of grain yield. In this study,we mapped quantitative trait loci (QTLs) associated with wheatspike traits using a recombinant inbred line (RIL) population (173 lines of F_8:9) derived from a cross of Shannong 01-35×Gaocheng 9411.The phenotypic data were collected in five environments and the high density genetic map was constructedusing90k SNP array,DArT technology and traditional molecular markers. In a combination analysis of five environments, many additive QTLs were detected includingseven for 1000-grain weight,eight for spike length,threefor grain number per spike, five for fertile spikelet number per spike, three for sterile spikelet number per spike,four for spikelet number per spike, and six for spike density.Some QTLs showed high rates of phenotypic variation explained (PVE). For example, the PVE of QTLs for 1000-grain weight on 1B, 4B, 5B and 6A ranged from 6.00% to 36.30%,with the favorable alleles from the large-grain parent Shannong 01-35; the PVE of QTLs for spike length ranged from 14.34% to 25.44%, and thatfor sterile spikelet number per spike from 8.70% to 37.70%. In addition to additive loci,32 pairs of epistatic QTLs were detected, which explained 0.05–1.05% of the phenotypic variations. The marker interval between EX_C101685 and RAC875_C27536 on chromosome 4B showed pleiotropic effectsin 1000-grain weight, spike length, grain number per spike, fertile spike number, sterile spikelet number, and spikelet number per spike, with the PVE ranging from 5.40% to 37.70%. There stable main QTLs were detected in multiple environments. Besides, markerinterval between wPt-0959 and TaGw2-CAPS on 6Ahad a locus controllingboth 1000-grain weight and spikelet number per spike. These results are valuable in developing molecular markers, fine mapping and cloning genes for spike traits in wheat.

Identification of bZIP Protein Family in Gossypium arboreum and Tissue Expression Analysis of GaFDs Genes

ZHANG Yan-Nan,CAI Da-Run,HUANG Xian-Zhong*

Acta Agron Sin. 2016, 42(06):  832-843.  doi:10.3724/SP.J.1006.2016.00832

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The basic leucine zipper (bZIP) is one of the largest and most diverse transcription factors in eukaryotes, and is involved in various processes of plant growth and development and in response to biotic and abiotic stresses. In this study, 159 bZIP family genes were identified and their complete gene sequences were obtained by using bioinformatics analysis method, based on Gossypium arboreumwhole genome database, and 159 bZIP genes were loaded on 13 chromosomes. The 159 bZIP genes were categorized into 13 groups based on their phylogenetic relationships, gene structures and conserved motifs. In addition, three GaFD homologous genes GaFD1, GaFD2 and GaFD3 were identified, which belongs to A subfamily in G. arboretum. The expression patterns of GaFD genes in different tissues were determined by using quantitative Real-time reverse transcription PCR (qRT-PCR) method. The results showed that GaFD1 and GhFD2 were preferentially expressed in the shoot apical meristem (SAM), whereas GaFD3 was preferentially expressed in stem. The results revealed that a number of bZIP family members exist in cotton genome, and FD genes with different structures and expression patterns play different roles in the development of cotton, which provides valuable information for dissecting the function and mechanism of bZIPs in cotton.

Establishment and Optimisation of Virus-Induced Gene Silencing in System Hydroponic Cotton

MU Chun,ZHOU Lin,LI Mao-Ying,DU Ming-Wei,ZHANG Ming-Cai,TIAN Xiao-Li,LI Zhao-Hu*

Acta Agron Sin. 2016, 42(06):  844-849.  doi:10.3724/SP.J.1006.2016.00844

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This experiment using GhCLA1 as a marker gene and cotton variety Guoxinmian 3 plants as material was conducted to explore effects of temperature, syringe-infiltrated concentrations and time, cultivation patterns, and cotton varieties on efficiency of tobacco rattle virus (TRV)-induced gene silencing (VIGS) under hydroponic condition. The results showed that higher silencing efficiency was induced by syringe-infiltrated time at 3 to 5 days after emergence and optimum growth temperature at 24 ºC under hydroponic condition, but syringe-infiltrated concentrations could not affect VIGS silence efficiency. Moreover, pTRV-GFP as null fragment could alleviate the adverse effect of inserted fragment for plant growth. Silencing phenotype could be visible earlier in hydroponics culture than in soil culture, and the experimental period was significantly shortened under hydroponic condition. In addition, GhCLA1 could be silenced in all tested varieties (lines) under hydroponic condition. Cotton plants with silenced GhCTR1 were severely dwarfed, which indicated TRV-VIGS system can be applied widely in hydroponic cotton.

Cloning and Expression Analysis of Anthocyanidin Synthase Gene BrcANS from Purple Non-heading Chinese Cabbage

XU Yu-Chao,HOU Xi-Lin,XU Wei-Wei,SHEN Lu-Lu,ZHANG Shi-Lin,LIU Shi-Tuo,HU Chun-Mei

Acta Agron Sin. 2016, 42(06):  850-859.  doi:10.3724/SP.J.1006.2016.00850

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Purple non-heading Chinese cabbage cultivar NJZX1-3, its green leaf mutant line NJZX1-0, and their progeny F₂: NJZX2-1 and NJZX2-2 were used to study the function of anthocyanidin synthase gene in the anthocyanin biosynthesis of non-heading Chinese cabbage leaf. Homology-based cloning was used and anthocyanidin synthase gene was respectively cloned from two cultivars (NJZX1-3 and NJZX1-0). The gene nucleotides and amino acids sequences found in the two materials and Chinese cabbage were exactly the same, with a length of 1077 bp and encoding a peptide with 358 residues. Furthermore, a 2OG-Fe (II) dioxygenase super family domain was found in the amino acid sequence from the 211th to the 307th amino acids and the gene was named as BrcANS. The homology between BrcANS protein and BjANS protein was up to 99%, in accordance with the close relationship between them. Their total anthocyanin content (TAC) was consistent with the degree of purple in fresh leaves of the four materials, of which total anthocyanin content in cultivar NJZX1-3 leaves was the highest, up to 80.15±5.74 mg 100 g^–1 FW. Simultaneously, the expression level of BrcANS (NJZX1-0 < NJZX2-1 < NJZX2-2< NJZX1-3) was positively correlated with the increasing trend of TAC. The mRNA of BrcANS exhibited tissue-specific expression in both materials, showing high level in leaves and lower level in other organs. In addition, the expression of two materials was significantly different, indicating that the expression of BrcANS in cultivar NJZX1-3 leaves was obviously higher than that in mutant line NJZX1-0. With the increasing of leaf age, the leaf color became shallow and the expression of BrcANS reduced. Meanwhile, the difference of expression between NJZX1-3 and NJZX1-0 decreased significantly. These results indicated that BrcANS gene is one of the key genes in the anthocyanin biosynthesis of non-heading Chinese cabbage leaf, and its expression level is directly related to the purple color of leaves, so the gene might regulate the formation of the purple color in leaves at transcriptional level.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Free Polyamines in Grains in Response to Soil Drought and Their Relationship with Grain Filling of Wheat

ZHANG Wei-Yang,XU Yun-Ji,QIAN Xi-Yang,LI Yin-Yin,WANG Zhi-Qin,YANG Jian-Chang*

Acta Agron Sin. 2016, 42(06):  860-872.  doi:10.3724/SP.J.1006.2016.00860

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For understanding the role of endogenous free polyamines on grain filling of wheat under drought stress, we conducted a two-year pot experiment from September 2013 to June 2015 using high-yield wheat cultivars Yangmai 16 and Ningmai 13 grown in different soil moisture conditions. Three treatments, namely well-watered (WW), moderate soil-drought (MD), and severe soil-drought (SD), were imposed from late-tillering to maturity stage. Grain filling rate and free polyamines levels in both superior and inferior grains were determined. The results showed the consistency between the two cultivars. Compared with WW, MD treatment had significantly increased grain-filling rate and grain weight in inferior grains by 12.5% and 11.8%, respectively; whereas no effect on grain filling in superior grains. In contrast, SD treatment showed negative influences on leaf water potential, photosynthetic rate, and grain filling. Under SD treatment, grain-filling rate and grain weight of superior grains reduced by 10.1% and 9.5% and those of inferior grains reduced by 14.5% and 11.7%, respectively. During grain filling, concentrations of free spermidine (Spd) and spermine (Spm) as well as their ratios to putrescine (Put) in inferior grains increased significantly under MD treatment and decreased significantly under SD treatment. Grain-filling rate and grain weight were positively correlated with concentrations of Spd and Spm, and the ratios of Spd/Put and Spm/Put (P < 0.01), whereas negatively correlated with Put concentration (P < 0.01). Exogenous Spd or Spm resulted in significant increases of grain-filling rate (11.2–25.9%) and grain weight (9.9–17.7%) in inferior grains under the three soil moistures and in superior grains under SD treatment, and had no significant difference in superior grains between WW and MD treatments. The positive effects of exogenous Spd and Spm were eliminated when their synthesis inhibitor, methylglyoxal-bis guanylhydrazone (MGBG), was applied together with Spd and Spm. Both superior and inferior grains showed great decreases of grain-filling rate (20.5–28.8%) and grain weight (16.9–28.5%) after spraying MGBG under the three soil moistures. These results indicate that the responses of polyamines in grain to soil moisture vary with drought strength, and moderate drought stress has a positive effect on grain filling through increasing concentrations of Spd and Spm and the ratios of Spd/Put and Spm/Put in grains.

Effects of Mulching and Nitrogen Application on Photosynthetic Characteristicsand Yield Traits in Broomcorn Millet

ZHOU Yu,SU Wang,WANG Jian, QU Yang,GAO Xiao-Li,YANG Pu,FENG Bai-Li

Acta Agron Sin. 2016, 42(06):  873-885.  doi:10.3724/SP.J.1006.2016.00873

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To reveal the mechanism of effects of mulching and nitrogen fertilizer on yield of broomcorn millet, we employed a split-plot design in variety Yumi 2 with mulching as main plot and nitrogen rates as subplot. In a three-year field experiment from 2011 to 2013, we investigated and related the variation of photosynthetic characteristics and yield traits indices under different mulching patterns and nitrogen rates. The results showed that compared with traditional planting (no mulching and no nitrogen), all mulching patterns and nitrogen fertilizer treatments could significantly increase chlorophyll content, net photosynthetic rate P_n, stomatal conductance G_sand transpiration rate T_r, and decrease intercellular CO₂ concentration C_i of flag leaves from flowering to maturity in broomcorn millet, among which “W” ridge covered with common plastic film + intredune covered with straw (M4) and 180 kg ha^–1 of nitrogen rate (N4) caused the most significant improvement on photosynthesis. All mulching patterns and nitrogen fertilizer treatments could significantly improve dry matter accumulation and allocation amount at flowering and maturity stages. In addition, the mulching and nitrogen fertilizer treatments significantly reduced pre-flowering reserves translocation and contribution to grain, but increased post-flowering assimilates allocation and contribution to grain. Mulching could significantly improve the grain yield, thousand grain weight, panicle grain number and panicle length of broomcorn millet, and M4 treatment showed the greatest improvement. With the increasing of nitrogen fertilizer rates, broomcorn millet grain yield and thousand grain weight increased at first and declined then, but panicle grain number and panicle length constantly increased. The best rate of nitrogen fertilizer applied in Loess Plateau was between 135 and 145 kg·ha^–1. Therefore, the combination of “W” ridge covered with common plastic film + intredune covered with straw and nitrogen rate from 135 to 145 kg·ha^–1 could be considered as the most efficient cultivation measure to broomcorn millet in Loess Plateau.

Accumulation, Distribution, and Utilization Characteristics of Phosphorus in Yongyou 12 Yielding over 13.5 t ha^-1#br#

WEI Huan-He,MENG Tian-Yao,LI Chao,ZHANG Hong-Cheng,DAI Qi-Gen,MA Rong-Rong,WANG Xiao-Yan,YANG Jun-Wen

Acta Agron Sin. 2016, 42(06):  886-897.  doi:10.3724/SP.J.1006.2016.00886

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In order to determine the absorption and accumulation of phosphorus (P) in super high yielding rice population of Yongyou 12, the field experiments were conducted with these populations of high yield (HY, 10.5–12.0 t ha^-1), higher yield (HRY, 12.0–13.5 t ha^-1), and super high yield (SHY, >13.5 t ha^-1) in 2013 and 2014. Results indicated that there was no significant difference in P content of plant at each growth stage among three yield groups. HY showed the highest P plant uptake while SHY the lowest at jointing among three yield groups. Opposite trends were observed at heading and maturity stages. There existed a significant (P<0.01) and negative correlation of the grain yield with P accumulation from sowing to jointing, while significant (P<0.01) and positive correlations of grain yield with P accumulation from jointing to heading, and from heading to maturity. P accumulation in the stem and sheath, leaf, and panicle at heading was 41.4, 8.5, and 8.9 kg ha^-1, respectively for SHY, higher than thosefor HRY (37.9, 7.6, 8.1 kg ha^-1) and HY (32.3, 6.8, 7.0 kg ha^-1). There existed significant (P<0.01) and positive correlations of grain yield with P accumulation in stem and sheath, leaf, and panicle at heading. P accumulation of SHY in stem and sheath, leaf, and panicle at maturity was 14.5, 4.4, 62.3 kg ha^-1, respectively, higher than those of HRY (13.6, 3.3, 55.9 kg ha^-1) and HY (11.2, 2.7, 48.7 kg ha^-1). There existed significant and positive linear correlation of grain yield with P accumulation in the stem and sheath, leaf, and panicle at maturity and with P translocation from stem and sheath to grain after heading. When values were averaged across two years,internal nutrient efficiency (kg grain kg^-1) and partial factor productivity (kg kg^-1) of SHY were 171.5 and 92.7, respectively, less than those of HRY (173.2, 99.6) and HY (173.5, 100.4). Harvest index of P of SHY was 0.768, significantly higher than that of HRY (0.761) and HY (0.758). SHY showed lower P accumulation before jointing, while higher P accumulation from jointing to heading, and from heading to maturity, when compared with check. There existed significant (P<0.01) and negative correlation of grain yield with P accumulation from sowing to jointing, while significant (P<0.01) and positive correlations of grain yield with P accumulation from jointing to heading, and heading to maturity. Relatively low P use efficiency was observed in SHY, a great attention should be paid to improving P use efficiency. Finally, methods to improve P use efficiency of SHY forYongyou 12 were discussed.

Optimization of Plant Density and Row Spacing for Mechanical Harvest in Winter Rapeseed (Brassica napus L.)

KUAI Jie,SUN Ying-Ying,ZUO Qing-So,LIAO Qing-Xi,LENG Suo-Hu,CHENG Yu-Gui,CAO Shi,WU Jiang-Sheng,ZHOU Guang-Sheng

Acta Agron Sin. 2016, 42(06):  898-908.  doi:10.3724/SP.J.1006.2016.00924

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The field experiment was conducted with the cultivar Huayouza 62, which was seeded at 15 (R15), 25 (R15), and 30 (R15) cm in row spacing and 15 (D1), 30 (D2), and 45 (D3) ×10⁴ plants hm^–2 indensity. The theoretical yield, leaf area index (LAI), pod area index (PAI), mechanical-harvested yield and yield loss were measured and calculated. Results showed that plant density and row spacing signi?cantly a?ected the seed yield of rapeseed. The yield was increased as the plant density increased or row spacing reduced. Compared with the planting patterns used by farmers (D2R25), D3R15 could achieve 14.1% increase in yield, which was the highest yield among all the treatments because of appropriate mortality, the highest LAI, PAI and the light interception (LI). Population biomass had the similar trend with yield while harvest index (HI) significantly increased with increasing plant density and row spacing. HI was significantly and negatively correlated with LI/ LAI (PAI), indicating that lower LI/ LAI (PAI) was favorable for increasing HI. Plant height and aboveground biomass reduced and root/shoot ratio increased with increasing plant density and row spacing, which led to decrease root and stem lodging. Improvement in resistance to pod shattering was also observed as plant density and row spacing increased. These changes all contributed to mechanical harvesting operations, resulting in reducing yield loss. As the regression equations showed, compared with D2R25, 43.8×10⁴ plants ha^–1 in combination with 21 cm row spacing was optimum for rapeseed to maximize seed yield and minimize lodging and pod shattering so as to facilitate mechanical harvest. The combination could make the LAI increase by 21.02%, light transmittance (LT) and LI/LAI decreased by 32.47% and 17.36%; PAI increased by 15.08%, LT and LI/PAI decreased by 32.04% and 3.30%.

Simulating Critical Nitrogen Dilution Curve and ModelingNitrogen Nutrition Index in Winter Wheat in Central Henan Area

YUE Song-Hua,LIU Chun-Yu,HUANG Yu-Fang,YE You-Liang*

Acta Agron Sin. 2016, 42(06):  909-916.  doi:10.3724/SP.J.1006.2016.00909

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To test the applicability of critical nitrogen dilution curve for estimating nitrogen (N) nutrient status of winter wheat in central Henan area, we carried out a site-fixed experiment from October 2011 to June 2014 using the large-spike variety Zhoumai 16 and the multi-spike varietyYumai 49-198. Five Napplication levels, namely pure N 0, 120, 180, 240, and 360kg ha-¹, were designed to build the critical N concentration dilution curveof shoot biomass and N nutrition index model. The aboveground biomass increased obviously with rising N level and then tended to a mild level. The relationship between critical N concentration and shoot biomass of wheat fit the power function with R²of 0.8203 for Yumai 49-198 and 0.7981 for Zhoumai 16 (P< 0.01).These models showed good stability across years. The N nutrition index estimated by the model could be used for evaluating the N nutrition situation of wheat plants, and a significant linear correlation was observed between the N nutrition index and the nitrate concentration in wheat stem base. These results indicate that the critical N concentration dilution model is applicable in diagnosing N nutrient status of wheat plants in central Henan area.

Relationship of Inferior Kernel Setting with Sink Strength under Controlling Pollination

LIANG Hong-Wei,GAO Ju-Lin,WANG Zhi-Gang*,YU Xiao-Fang,SUN Ji-Ying,HU Shu-Ping,WANG Zhen,YU Shao-Bo,LI Ya-Jian

Acta Agron Sin. 2016, 42(06):  917-923.  doi:10.3724/SP.J.1006.2016.00917

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Clarifying the relationship of sink capacity and/or sink activity with kernel abortion and/or filling stagnation of inferior kernels, is of great importance for closing the yield gap by improving the grain filling of inferior kernels of maize. In this present study, two typical commercial maize hybrids Zhengdan 958 and Pioneer 335 were planted at two locations. At silking stage, two pollination treatments, incomplete pollination (IcP) and complete pollination (CP), were imposed to each cultivar at each location. The objective of incomplete pollination, in which the pollinated filaments within the basal region of the ear was decreased by handing-pollinating, was to stimulate the inferior kernel set in the apical region of the ear, where the inferior kernels should be aborted or filling-stagnated in complete pollination. The sink capacity, sink activity and grain filling parameters were compared within IcP and CP treatments. The endosperm cell division process and the maximum endosperm cell number of inferior kernels showed no difference between IcP and CP treatments, while the soluble acid invertase activity of IcP was significantly higher than that of CP, by 12.6% on an average and 21.8% at the maximum. Furthermore, the actual 100-kernel weight, the stimulated final kernel weight, the maximum kernel-filling rate and the mean kernel-filling rate of IcP treatment were also higher than those of CP. The results suggested that the abortion and/or filling stagnation of inferior kernels of maize is not limited by its sink capacity; sink activity during blister stage is the primary limited factor of the abortion and/or filling stagnation of inferior kernels.

RESEARCH NOTES

Effect of Mechanized Transplanting with High Hill Density and Single Seedling per Hill on Growth and Grain Yield in Super Rice

XIE Xiao-Bing,WANG Yu-Mei,HUANG Min,ZHAO Chun-Rong,CHEN Ja-Na,CAO Fang-Bo,SHAN Shuang-Lü,ZHOU Xu-Feng,LI Zhi-Bin,FAN Long,GAO Wei,ZOU Ying-Bin*

Acta Agron Sin. 2016, 42(06):  924-931.  doi:10.3724/SP.J.1006.2016.00924

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The high sowing rate and poor transplanting performance hinder a large-scale mechanized transplanting of hybrid rice in China. In order to study the effects of mechanized transplanting with high hill density and single seedling per hill (MTHS) and conventional mechanized transplanting (CMT) on tillering, dry matter accumulation, radiation use efficiency, grain yield and its components, comparisons of seedling quality between printing sowing and conventional sowing, and field experiments between MTHS and CMT were conducted using hybrid rice cultivar Taiyou 390 and Wuyou 308 at Liuyang, Hunan Province and using Wuyou308 at Zhaoqing, Guangdong province. The results showed that leaf age, white root number, total root number, basal width of shoot, dry weight of shoot and dry weight of root of the printing sowing were more than those of the conventional sowing at two locations. The MTHS had significantly less maximum tiller number and effective tiller number than CMT, but had more spikelets per panicle and spikelets per m², higher grain setting rate and 1000-grain weight, as well as significantly increased grain yield by 10.28−13.96%. On the other hand, The MTHS had more primary branch number and secondary branch number, longer panicle length, higher grain density and panicle weight than CMT, with significant differences. Although the MTHS had less dry matter accumulation and lower LAI than CMT before the heading stage , produced more dry matter at physiology maturity and had significantly higher harvest index and radiation use efficiency. Therefore, the MTHS could produce high grain yield for hybrid rice due to not only reducing sowing rate and improving seedling quality, but also increasing spikelets per panicle, spikelets per m² and 1000-grain weight and improving grain setting rate, harvest index and radiation use efficiency.

Development of 295 InDel Markers for Indica andJapanicaRice

CHU Zhi-Zhan,GUO Hai-Bin,ZENG Dong-Chang,LIU Yao-Guang

Acta Agron Sin. 2016, 42(06):  932-941.  doi:10.3724/SP.J.1006.2016.00932

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Insertion/Deletion (InDel) markers have advantages of simplicity and reliability for genotyping.We selected 634 candidate InDelmarkers distributing throughout the 12 chromosomes of riceby comparing genome sequences between the japonica cultivarNipponbare and the indica cultivar 93-11. PCR results of these candidate markers betweentwojaponica(Nipponbare and Taizhong 65) and twoindica（9311 and Huanghuazhan）cultivars revealed that295 InDelmarkersdisplayed common polymorphisms between the japonica and indicacultivars which is useful for gene mapping and molecular breeding involving inindica andjaponicasubspecies.