Table of Content

12 June 2014, Volume 40 Issue 06

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Genetic Similarity and Specificity of Ten Important Soybean Cultivar Families Released in China

XIONG Dong-Jin,WANG Wu-Bin,ZHAO Tuan-Jie,GAI Jun-Yi

Acta Agron Sin. 2014, 40(06):  951-964.  doi:10.3724/SP.J.1006.2014.00951

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Analysis of the affinity relationship and genetic similarity among cultivars is important for crop genetic improvement. In this study, a total of 161 SSRs covering the entire soybean genome were analyzed for the genetic diversity, similarity and specificity of 10 important families composed of 179 cultivars using PowerMarker Ver. 3.25. The results showed that there were totally 1697 alleles, averaging 10.5 per locus, ranging from 5 to 24 with average polymorphism information content of 0.832, ranging from 0.545 to 0.943 in the population. According to the SSR cluster analysis, the 179 cultivars were clustered into six groups, eleven subgroups, with a tendency that the cultivars in a family tended to be grouped into a same cluster. There existed significant correlation (r = 0.67) between coefficient of parentage (CP) and genetic similarity coefficient (GSC) of the population. The CP and GSC values of A295, A133, A122, and A231 families were relatively low, which means that the genetic bases of the four families were relatively broad. In contrast, the CP and GSC values of A291, A201, A084, and A002 families were relatively high, indicating their genetic bases were relatively narrow due to more cultivars obtained from pure line selection. The CP and GSC values between the A019 family from Northeast China and other nine families were the lowest among all pairwise combinations of families. The genetic specificity analysis showed that there existed much more complementary alleles, specifically existent and specifically deficient alleles in A019 in comparison with in other families, indicating the former is distant from the latter. On the other hand, the families in Eco-region II and III, contained fewer complementary alleles, specifically existent and specifically deficient alleles, which might be due to some frequent germplasm exchange between the neighboring eco-regions. For example, there were no specifically existent alleles in A002, A231, A122 and no specifically deficient alleles in A084, A201, A034, and A231. The present results are of significance in broadening the genetic basis of soybean cultivar.

Development of Molecular Markers and Map Integration for Seed Color Traits in Dahuang Rape (Brassica rapa L.)

ZHAO Hui-Yan,XIAO Lu,ZHAO Zhi,DU De-Zhi*

Acta Agron Sin. 2014, 40(06):  965-972.  doi:10.3724/SP.J.1006.2014.00965

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 A BC₄ population and a F₂ population, derived from the cross between Dahuang and 09A-126 (brown seed, B. rapa), were constructed. AFLP (amplified fragment length polymorphism) methodology and bulked segregant analysis (BSA) were used to get five AFLP markers closely linked to yellow-seeded gene Brsc1, termed Y11–Y15 respectively. Five AFLP specific fragments were homologue with some sequences on chromosome A09 of Brassica rapa, which we converted into five SCAR markers, termed SC11–SC15. Seven SSR markers, BrID10607, KS10760, B089L03-3, A1–A4, tightly linked to Brsc1 were developed in the region of chromosome where Brsc1 was located. With five SCAR markers and seven SSR markers used for genotyping in F₂ population, SC14 and A1 were confirmed as co-dominant markers. Using BC₄ population, Brsc1 was located in the region of 1.7 Mb between Y06 and A04 on chromosome A9 with genetic distances of 0.115 cM and 0.98 cM. Y05 and Y12 co-segregated with Brsc1. The results were useful for developing yellow-seeded rapeseed lines by marker-assisted selection (MAS), and also laying the foundation for fine mapping and map-based cloning of Brsc1.

Exploring Assessment Method of Chinese Rice Backbone Parents

SUN Zong-Xiu**,*,E Zhi-Guo**,WANG Lei,ZHU De-Feng,ZHANG Yu-Ping,HU Guo-Cheng,LIU Wen-Zhen,FU Ya-Ping*

Acta Agron Sin. 2014, 40(06):  973-983.  doi:10.3724/SP.J.1006.2014.00973

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Parent is the basis of crop breeding, while backbone parent refers to the breeding material that derives many varieties (lines) and owns large planting area within the same generation of breeding parents in the same period. Determining backbone parents will not only enable us to learn breeding history and parental contribution, but also play an important role in guiding practical breeding. We try to establish an objective methodology of assessing backbone parents. This paper analyzed main problems in determining backbone parents in the past, and suggested that certain norm should be followed to assess backbone parents, that is to say, carrying out quantitative comparison of improved varieties (lines) in the same period and the same derivative generations. A total of 2398 rice varieties (lines) in Chinese rice database were classified based on subspecies and grouped according to breeding time. The quantities of varieties (lines) and planting areas for three generations continuously were used as parameters to analyze the application of improved varieties in the further breeding research. On this basis, 49 backbone parents, including 26 parents of indica rice and 23 parents of japonica rice, for rice breeding in the second half of the 20th century were selected by adopting quantitative assessment method. Taking rice as an example, the paper brought forward assessment principle and method of backbone parent, and also provided some suggestions about choosing breeding parents and improving breeding efficiency in the future.

Characterization of Tamyb10 Haplotypes and Their Association with Pre-harvest Sprouting Resistance in a Set of Chinese Red-Grained Wheats

WANG Gen-Ping,BI Hui-Hui,SUN Yong-Wei,WANG Cheng-She,XIA Lan-Qin

Acta Agron Sin. 2014, 40(06):  984-993.  doi:10.3724/SP.J.1006.2014.00984

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Pre-harvest sprouting (PHS) is one of important factors affecting yield and quality of wheat (Triticum aestivum L.). Generally, red-grained wheat has higher PHS resistance than white wheat. Transcription factor Tamyb10 is a strong candidate for R-1 gene and the expression of its homologues determines wheat seed coat color. In this study, we attempted to analyze the relationship between Tamyb10 haplotype and PHS resistance using amplification result of Tamyb10 specific markers and germination index (GI) evaluated in two locations over two years. In the 119 red-grain Chinese wheat varieties collected from different wheat growth zones in China, seven Tamyb10 haplotypes (Tamyb10-A1, Tamyb10-B1, and Tamyb10-D1 locus) were detected, namely baa, aba, bba, aab, bab, abb, and bbb. Tamyb10 haplotypes were associated with GI value. Tamyb10-D1 had the greatest effect on PHS resistance, followed by Tamyb10-B1 gene, and Tamyb10-A1 had the least effect. Tamyb10 haplotypes distribution showed no obvious regional characteristic, butTamyb10 haplotype bbb correlated with high PHS resistance in the Northeast Spring Wheat Region in China.

Expression of Ta6-SFT Gene in Tobacco Induced by Drought Stress

LI Shu-Jie,LI Jing-Wen,ZHANG Zheng-Ying

Acta Agron Sin. 2014, 40(06):  994-1001.  doi:10.3724/SP.J.1006.2014.009949

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To obtain better Ta6-SFT gene expression efficiency in transgenic plants, we constructed two Ta6-SFT gene expressionvectors driven by CaMV35S promoter and rd29Apromoter, transformed them into tobacco mediated by Agrobacterium tumefaciens, respectively. Transgenic plants were confirmed by PCR, Southern blot and Northern dot blot. The two types of transgenic line were treated with 18 day drought stress, non-transgenic tobacco as a control. Expression of Ta6-SFT was detected with semi-quantitative RT-PCR at the beginning of stress and 18 days of treatment. In addition, fructan concentration and some agronomic traits such as plant height, stem diameter at half of plant height, and leaf area were analyzed at the same time. The results showed that Ta6-SFT expression level was more active and fructan content was higher under drought stress in rd29Apromoter driven transgenic lines. Agronomic traits and physiological measurement indicated that the transgenic lines carrying Ta6-SFT driven byrd29Apromoter had stronger growth vigor under the drought stress than that by CaMV35S promoter. It follows that Ta6-SFT gene inducible expression driven byrd29Apromoter could make transgenic lines have better stress tolerance.

Cloning and Expression of Sugarcane S-Adenosylmethionine Synthetase Gene ScSAM

SONG Xiu-Peng,ZHANG Bao-Qing,HUANG Xing,YANG Li-Tao,LI Yang-Rui

Acta Agron Sin. 2014, 40(06):  1002-1010.  doi:10.3724/SP.J.1006.2014.01002

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The full-length sequencecDNA of ScSAM (GenBank accession number: KC172558) was cloned from sugarcane variety ROC 22 using RT-PCR combined with RACE techniques. This sequence consists of 1466 bp with an intact open reading frame of 1191 bp, encoding a polypeptide of 396 amino acids. Homology analysis showed that the deduced ScSAM protein was highly homologous to SAM proteins from different species. Phylogenetic analysis indicated that ScSAM was closely related to the SAM of sorghum. Real-time PCR results showed that the ScSAM gene constitutively expressed in plant, with different expression levels in root, stalk and leaf. The transcript of ScSAM in root was the highest among the three organs, which was 3.6 times higher than that in leaf. Furthermore, ScSAM transcription was induced by biotic (smut infection) and abiotic (low temperature, PEG and NaCl) stresses, but the expression patterns were different. Under oxidative stress (H₂O₂), the expression of ScSAM was inhibited. We suggested that ScSAM might participate in smut-resistant activities in sugarcane, and also play a role in sugarcane resistances to chill, drought, salt and oxidation stresses.

Cloning and Interaction between Transcription Factors SPT and HEC1 of Pistil of Brassica oleracea L.var. capitata L.

XU Jun-Qiang,SUN Zi-Jian,LIU Zhi-Yu,YANG Pu-Li,TANG Qing-Lin,WANG Zhi-Min,SONG Ming*,WANG Xiao-Jia*

Acta Agron Sin. 2014, 40(06):  1011-1019.  doi:10.3724/SP.J.1006.2014.01011

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To explore interaction of SPT and HECs in cabbage pistil development, we took stigma of self-incompatibility line E1 to obtain total RNA for first-strain cDNA synthesis, and cloned SPT gene fragment with the ORF of 1062 bp and HEC1 gene with 696bp by using primers according to SPT and HEC1 genes in Arabidopsis. Amino acid sequence analysis showed that SPT and HEC1we cloned encoded 353 and 231 amino acid residues, respectively; the predicted molecular weight of SPT protein was 37.67 kD, with pI of 6.83; the predicted molecular weight of HEC1 protein was 25.26 kD, with pI of 10.23. Relative expression of SPT was the highest in the fruit and pistil, that of HEC1 was the highest in the root and bud. Prokaryotic expression plasmids pCold I-SPT and pGEX-HEC1 were constructed and then transformed into E. coli Rosetta (DE3). The Pull-down assay showed that the two tagged expression products could interact with each other. To verify the interactions furtherly, we constructed yeast expression vectors pGBKT7-SPT, pGADT7-HEC1, and pGADT7-SPT, pGBKT7-HEC1 to transform into yeast Y2HGold and Y187 strains, respectively. Finally, diploid yeast showed positive results in SD/–Ade–Trp–Leu–His/X-α-gal/AbA synthetic dropout. It demonstrated that interaction between SPT and HEC1 can activate HIS3, AUR1-C,and ADE2 reporter genes downstream. Yeast two-hybrid experimental results as well as the pull-down assay showed that SPT and HEC1 can form heterodimer to regulate the development of pistil.

Physiological Characteristics and Genetic Analysis on a Spotted-Leaf Wheat Derived from Chemical Mutation

DU Li-Fen,LI Ming-Fei,LIU Lu-Xiang,WANG Chao-Jie,LIU Yang,XU Xi-Tang,ZOU Shu-Fang,XIE Yan-Zhou,WANG Cheng-She

Acta Agron Sin. 2014, 40(06):  1020-1026.  doi:10.3724/SP.J.1006.2014.01020

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A light and temperature affected spotted-leaf mutant LF2010 (Triticum aestivum L.) was obtained from a mutagenic treatment with EMS on a wheat line H261. The bright yellow spot became evident once the third leaf will expanded, then covered later leaves and leaf sheaths of the whole plant including tissues of spike. The mutant plants differed from normal plants in terms of total chlorophyll content and net photosynthetic rate once symptom appeared on the leaves. The plant height, spike length, spike number per plant, grain weight per plant, grain number per spike, seed setting rate, and flag leaf length were lower in the mutant than in the wild type. However, the 1000-grain weight and flag leaf width of the mutant had no significant difference with those of the wild type. Genetic analysis based on F₁, F₂, and BC₁ populations revealed that the yellow spot trait was controlled by a single recessive gene.

Cloning and Expression Analysis of an F-box Gene (SiFBX) Rapidly Responsive to Drought Stress

IN Heng,YU Qin-Yang,AN Li-Jia,LI Wen-Li

Acta Agron Sin. 2014, 40(06):  1027-1034.  doi:10.3724/SP.J.1006.2014.01027

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F-box proteins, components of the Skp1-Cullin1-F-box (SCF) protein E3 ubiquitin ligase complex, serve as the variable component responsible for substrate recognition and recruitment in SCF-mediated proteolysis. The anti-drought relative gene of SiFBX (GenBank accession number KC252635.1) which belongs to the F-box super family was cloned from foxtail millet (Setaria italic). The full-length cDNA of SiFBX was 510 bp, which encoded 170 amino acid residues. Protein analysis and structure predication showed that it had a higher proportion of arginine (R), leucine (L), and serine (S) and a lack of trans-membrane domains and signal peptide. Phylogenetic analysis demonstrated that SiFBX had similarity with EID1 and FBW4. Many abiotic stress-related cis-acting elements and transcription factors were discovered in the 1.9 kb upstream region of SiFBX. The results of real-time PCR showed that there were remarkable changes in the expectation level of SiFBX for the treatments with PEG, water-withholding and ABA.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Potassium Accumulation, Distribution, and Utilization in Wheat with Yield Potential of 9000 kg ha−1 in Rice-Wheat Rotation System

DING Jin-Feng,ZI Yan,YANG Jia-Feng,PAN Ting,FENG Chao-Nian,ZHU Xin-Kai,LI Chun-Yan,PENG Yong-Xin,GUO Wen-Shan*

Acta Agron Sin. 2014, 40(06):  1035-1043.  doi:10.3724/SP.J.1006.2014.01035

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Different wheat populations of Yangmai 20 were established in the rice-wheat rotation system by managing plant density and nitrogen application amount, timing and splitting ratio in 2010–2011 and 2011–2012 growing seasons. These populations were divided into high yield (HY, <9000 kg ha^-1) and super high yield (SHY, ≥9000 kg ha^-1) groups. Characteristics of potassium (K) uptake and utilization in both population groups were compared to guide high-yield wheat production in the rice-wheat rotation system. In SHY population, K absorption from elongation to anthesis was greater than that of other growing periods, which accounted for 52–68% of the total K uptake. The K accumulation amounts at anthesis and maturity were significantly higher in SHY population than in HY population. At maturity, K accumulation amount in leaf, stem, rachis + hull, and grain was positively correlated with grain yield. After anthesis, K translocation amount from stem to grain was positively correlated with grain yield, whereas K translocation amount from rachis + hull to grain was negatively correlated with grain yield. In SHY population, K accumulation amount was 430–450 kg ha^-1 at anthesis and 366–408 kg ha^-1 at maturity; K accumulation amounts at maturity were 46–49 kg ha^-1 in leaf, 244–269 kg ha^-1 in stem, 40–46 kg ha^-1 in rachis + hull, and 35–46 kg ha^-1 in grain; K translocation amount at anthesis from stem to grain was 46–52 kg ha^-1; and K accumulation amount in rachis + hull from anthesis to maturity was 9–17 kg ha^-1. For yielding grain higher than 9000 kg ha^-1, winter wheat in the rice-wheat rotation system required 4.57–4.87 kg K nutrient to produce 100 kg grain. Meanwhile, the K use efficiency and K harvest index were 20.56–22.02 kg kg^-1 and 0.095–0.112, respectively.

Tillering Characteristics of Indica Hybrid Rice under Mechanized Planting

LEI Xiao-Long,LIU Li,LIU Bo,HUANG Guang-Zhong,MA Rong-Chao,REN Wan-Jun

Acta Agron Sin. 2014, 40(06):  1044-1055.  doi:10.3724/SP.J.1006.2014.01044

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In order to explore tillering characteristics and its relationships with yield of indica hybrid rice with mechanized planting and different sowing dates, a split plot field experiment was conducted using F you 498 with mechanized direct-seeding, mechanized transplanting and artificial transplanting and two sowing date treatments. The main results are as follows: (1) The major and stable contribution to yield was from primary tillers group, ranging from 58.67% to 63.82% among different planting methods. The contribution to yield from main stem was significantly different, with the highest in mechanized direct-seeding and the lowest in artificial transplanting. Yield of secondary tillers group was much lower in mechanized direct-seeding than in mechanized and artificial transplanting. (2) The tillering and panicle formation pattern was different for different planting methods which had a changing trend with a single peak for mechanized direct-seeding and transplanting and with two peaks for artificial transplanting. Tillers of mechanized direct-seeding had early and fast emergence and its primary tillers group emerged from leaf 1 to leaf 8, among which tillers from leaf 1 to leaf 4 had higher percentage of emerging and earbearing, and secondary tillers group earbeared mainly in leaf 1 and leaf 2. Tillers of mechanized transplanting had relatively late, low and concentrated emergence, the primary tillers group mainly emerged from 3/0 to 8/0, among which leaf position of 3/0 to 6/0 had higher rate of panicle formation, and secondary tillers group emerged and earbeared mainly in leaf 3, leaf 4, and leaf 5. The number of tillering leaf positions of artificial transplanting was more and tillering time was longer in seeding bed and field. The primary tillers group mainly emerged from leaf 1 to leaf 8 besides leaf 3, among which the tillers of leaf 1, leaf 2, leaf 4, leaf 5, and leaf 6 had higher earbearing percentage, secondary tillers group emerged and earbeared mainly in leaf 1 and leaf 2. The number of tillering and earbearing leaf positions and yield decreased with delaying sowing date. (3) The main stem and primary tillers in low and middle earbearing leaf positions had larger number of earbearing tiller branches, spikelets per panicle, grain weight and grain weight per panicle among three planting methods. The number of earbearing tiller branches and spikelets per panicle of secondary tillers and primary tillers in high earbearing leaf positions were fewer, so their panicles were small. Leaf 1 to leaf 4 in mechanized direct-seeding, leaf 3 to leaf 6 in mechanized transplanting and leaf positions of 1, 2, 4, 5 and 6 in artificial transplanting were the superior leaf positions. Their contributions to yield were 70.51%, 73.83% and 76.81%, respectively. The tillers group of superior leaf positions in each planting method had higher rates of tiller emerging and panicle formation, larger panicles and higher contribution to yield. Thus, we should optimize agronomic measures for tillers of superior leaf positions to increase yield potential.

Effects of Alternate Wetting and Drying Irrigation during Grain Filling on the Seed-Setting Rate and Grain Weight of Two Super Rice Cultivars

FU Jing,LIU Jie,CAO Zhuan-Qin,WANG Zhi-Qin,ZHANG Hao,YANG Jian-Chang

Acta Agron Sin. 2014, 40(06):  1056-1065.  doi:10.3724/SP.J.1006.2014.01056

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Two super rice cultivars, Liangyoupeijiu and Huaidao 9, were used in the study. Three irrigation regimes, including alternate wetting and moderate soil drying (WMD), alternate wetting and severe soil drying (WSD), and conventional irrigation (CI, continuous flooding), were imposed from heading to maturity. Compared with CI, WMD significantly increased, whereas WSD decreased, seed setting rate and grain weight of super rice. The photosynthetic rate, activities of membrane lipid peroxidation enzymes in the flag leaf, root oxidation activity, root absorption surface area, root active absorption area, root specific surface area, contents of zeatin + zeatin riboside (Z+ZR) and indole-3-acetic acid (IAA) in roots and the ratio of root to shoot were increased under the WMD regime, but decreased under the WSD regime. The results suggest that the WMD irrigation during grain filling could improve root and shoot physiological functions, and consequently increase the seed-setting rate and grain weight of super rice.

Difference of Root Morphological and Several Physiological Characteristics between Indica and Japonica Super Rice Varieties

GONG Jin-Long,XING Zhi-Peng,HU Ya-Jie,ZHANG Hong-Cheng*,DAI Qi-Gen,HUO Zhong-Yang,XU Ke,WEI Hai-Yan,GAO Hui,GUO Bao-Wei

Acta Agron Sin. 2014, 40(06):  1066-1080.  doi:10.3724/SP.J.1006.2014.01066

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The objective of this study was to reveal the difference of dry matter accumulation and its distribution, and the main morphological and physiological characteristics in roots between indica and japonica super rice, and their relationship with yield formation. A field experiment was conducted using two main representative super hybrid indica combinations and two conventional japonica super rice varieties in wheat-rice double cropping regions. Dry weight of root, total root length, root number, root volume, root absorbing area, root germination ability and root bleeding intensity after heading for both single stem and population, root-shoot ratio, single root length, root diameter, root density, root bleeding per spikelet, root distribution in the soil at heading and yield components were analyzed systematically. Results showed as follows: (1) For the whole growth duration, root-shoot ratio, single root length, root germinating number, root germinating volume, root germinating dry weight, root bleeding per spikelet, number of panicles, total spikelets, seed-setting rate and grain yield of japonica rice were higher thanthose of indica rice, while root diameter, spikelets per panicle and 1000-grain weight followed an opposite tendency, with root-shoot ratio, single root length, root bleeding per spikelet, number of panicles, spikelets per panicle, seed-setting rate and grain yield being a significantly different. (2) Before heading, dry weight of root, total root length, root number, root volume and total absorbing surface area of root per stem and root density of japonica rice were lower than those of indica rice, though not significantly, and higher than those of indica rice significantly at maturity. (3) Before jointing, active absorbing surface area per stem and ratio of active absorbing surface area to total absorbing surface area in japonica rice were less than those in indica rice significantly, which showed an opposite trend after jointing. (4) Population indicators of morphological and physiological characteristics of japonica rice except for population root dry weight at jointing and root number of population at jointing and heading were higher than those of indica rice significantly. (5) Root bleeding intensity during 0–35 d after heading was higher in japonica rice than in indica rice significantly whether it was based on a single stem or population. (6) Ratio of root dry weight in the 0–10 cm layer to total root dry weight was lower in japonica rice than in indica rice significantly, with an opposite trend for the >10 cm layer, which indicated the deep-rooted characteristic of japonica rice can strengthen its resistance to lodging and premature senescence. Compared with super hybrid indica rice, root growth advantages of conventional japonica super rice after heading were increased, especially for population growth advantages, and all the root morphological and physiological characteristics indicators of japonica rice at maturity were better than those of indica rice, which is the important cause and assurance for high-yielding formation of japonica rice.

Effects of Nitrogen Application and Film Mulching on Yield Performance Parameters and Nitrogen Use Efficiency of Spring Maize in the Middle Reaches of Yangtze River

GE Jun-Zhu,LI Shu-Ya,ZHONG Xin-Yue,YUAN Guo-Yin,XU Ying,TIAN Shao-Yang,CAO Cou-Gui,ZHAI Zhong-Bing,LIU Shi-Qing,ZHAN Ming,ZHAO Ming

Acta Agron Sin. 2014, 40(06):  1081-1092.  doi:10.3724/SP.J.1006.2014.01081

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A two-year field experiment using maize hybrid Yidan 629 with nitrogen(N) application and film mulching was conducted in Wuxue, Hubei Province, during 2012–2013 growing season to study the characteristics of yield performance parameters and N use efficiency of spring maize in the middle reaches of Yangtze River. The results showed that film mulching could make an earlier seed germination times of 7–8 d, N application and film mulching could promote the vegetative growth of spring maize, the tasseling stage and silking stage were advanced 8–12 d and 6–11 d, respectively, the maturity stage advanced 2–7 d and the physilogical maturity stage advanced 3–6 d. Compared with the control, the yield performance parameters of spring maize such as mean leaf area index (MLAI), mean net assimilation rate (MNAR), harvest index (HI), grain number per ear (GN) and 1000-kernels weight (GW) increased by 81.18%–112.38%, 19.20%–25.82%, 72.61%–95.30%, and 13.09%–21.26% in N application treatment, and increase 11.12%–17.12%, 0.80%–10.66%, 0.44%–6.50%, 7.02%–16.07%, and 5.64%–7.93% in film mulching treatment. With the super compensative effect of yield performance parameters, the grain yield of spring maize increased by 6.80%–24.66% and 7.16%–22.19%, respectively, resulting from N application and film mulching. The N use efficiency was significantly reduced with increasing N application, the partial factor productivity (PFPN) and nitrogen agronomic efficiency (ANUE) were decreased 31.34%–51.20% and 30.39%–42.12%. Film mulching enhanced N absorbing ability of spring maize, and increased PFPN and ANUE 18.30%–31.67% and 25.83%–56.80%, respectively. Comprehensive considering the super compensative effect of yield performance parameters and the characteristics of N use efficiency, achieving high yield of 8995–9220 kg ha^-1 in spring maizeneeds the N application of 202.5–270 kg ha^-1 with film mulching in the middle reaches of Yangtze River.

Yield and Lodging Resistance of Summer Maize under Different Winter Wheat-Summer Maize Tillage Systems

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

Acta Agron Sin. 2014, 40(06):  1093-1101.  doi:10.3724/SP.J.1006.2014.01093

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The objective of his study was to explore the effects of different tillage systems in winter wheat-summer maize cropping on yield and lodging resistance of summer maize. Maize hybrid Zhengdan958 was used as experimental material. Three tillage treatments were designed, including rotary tillage before winter wheat seeding and no-tillage before maize seeding (RN), moldboard tillage before winter wheat seeding and no-tillage before maize seeding (MN), and moldboard tillage before winter wheat seeding and rotary tillage before maize seeding (MR). The results showed that plant height and ear height were higher in MR than in RN, the third internode diameter of MN and MR was greater than that of RN, and the ratio of length to diameter in MN was the lowest and the stem diameter coefficients of MN was the highest. Rind penetrometer resistance of summer maize enhanced at the tasselling stage (VT) and reduced at the milk stage (R3) in the treatment of moldboard tillage before winter wheat seeding, density of the vascular and area of the vascular bundle were increased, and bleeding sap in stalk increased under MR and MN. Bleeding sap of stalks under MR and MN was 60.62% and 46.70% greater than under RN respectively. Root and shoot dry matter, the ratio of root and shoot dry matter, and brace root numbers of summer maize in MN and MR were higher than these in RN. Grain yield of MR and MN was 26.33% and 39.21% greater than that of RN, respectively. In conclusion, moldboard tillage before winter wheat seeding has good effects on yield and lodging-resistant capability in summer maize.

Effects of Waterlogging, High Temperature and Their Interaction after Anthesis on Grain Protein Components and Flour Color in Wheat

ZHANG Yan-Fei,WANG Chen-Yang,MA Dong-Yun,LU Hong-Fang,ZHU Yun-Ji,XIE Ying-Xin,GUO Tian-Cai

Acta Agron Sin. 2014, 40(06):  1102-1108.  doi:10.3724/SP.J.1006.2014.01102

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Waterlogging and high temperature after anthesis are main meteorological disasters to winter wheat growing in the middle and lower Yangtze Valley. The objective of this study was to evaluate the effects of waterlogging, high temperature, and their interaction on grain yield, protein component content, and flour color of wheat. In a two-year pot experiment from October 2011 to October 2013, wheat cultivars Zhengmai 366 and Zhengmai 004 differing in gluten strength were treated with waterlogging (WL) and/or high temperature (HT) stress from the 5th to 14th day after anthesis. In the 2011–2012 growing season, 1000-grain weights of both cultivars were reduced significantly under WL, HT, and WL+HT stresses, and the reduction percentages were 10%, 23%, and 16% in Zhengmai 366 and 7%, 27%, and 32% in Zhengmai 004, respectively. Similar influence was repeated in the 2012–2013 growing season, but the reduction percentages were smaller. In both cultivars, the contents of grain protein and protein components were decreased under WL stress and increased under HT stress. However, the effect of WL+HT on grain protein varied with cultivars. The contents of protein and its components in Zhengmai 004 significantly increased under WL+HT in both years, whereas, those in Zhengmai 366 had no significant changes in 2011–2012 growing season and had significant reductions in 2012?2013 growing season. The flour color was obviously affected by stresses in both cultivars. Under WL, HT, and WL+HT, the flour L-value decreased by 0.9%, 1.2%, and 1.9% in Zhengmai 366 and by 0.2%, 2.1%, and 1.7% in Zhengmai 004; the a-values increased by 14%, 33%, and 43% in Zhengmai 366 and by 0.3%, 76%, and 42% in Zhengmai 004; the b-values increased by 4%, 2%, and 11% in Zhengmai 366 and by 4%, 7%, and 8% in Zhengmai 004, respectively. Protein and glutenin contents had a close relationship with the flour whiteness, having the negative effect on flour L-value significantly, and the positive effect on flour a-value and b-value significantly.

Effects of Nitrogen Fertilizer and Planting Density on Yield Loss Percentage of Mechanical Harvesting in Rapeseed

ZUO Qing-Song,CAO Shi,YANG Shi-Fen,HUANG Hai-Dong,LIAO Qing-Xi,LENG Suo-Hu,WU Jiang-Sheng,ZHOU Guang-Sheng

Acta Agron Sin. 2014, 40(06):  1109-1116.  doi:10.3724/SP.J.1006.2014.01109

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In this study, Huayouza 62 was planted by direct-seeding with three nitrogen (N) fertilizer levels (120 kg N ha^–1, 180 kg N ha^–1, and 240 kg N ha^–1) and three planting densities (15´10⁴ plant ha^–1, 30´10⁴ plant ha^–1 and 45´10⁴ plant ha^–1). The yield loss percentages of mechanical harvesting were investigated when the moisture contents in seeds ranged from 10.86% to13.17%. The results showed the total yield loss percentage was from 6.13% to 7.82% in different treatments. There existed differences in the ratio of the yield loss in different parts to the total yield loss. The ratio of the yield loss caused by shattering (SL) to the total yield loss was the least in different treatments, ranging from 2.41% to 3.90%. The ratio of the yield loss caused by combine header (CHL) to the total yield loss ranged from 17.99% to 21.99%. The ratio of the yield loss caused by cleaning and threshing (CTL) to the total yield loss ranged from 74.15% to 79.52%, among which the yield loss caused by mixed straw and shell (ML) was the main part (from 65.51% to 69.05%), and the yield loss caused by non-threshing pod (NTPL) was low with the range from 8.64% to 10.47%. The plot yield increased with increasing N application rates and planting densities. The total yield loss percentage had extremely significant positive correlation with plot yield (r = 0.970^**) and N fertilizer (r = 0.918^**), and no significant correction with planting density (r = 0.358). The results of this study indicated that in the rapeseed mechanical production, appropriate N fertilizer and planting density should be applied for high yield, and then the yield loss percentage should be reduced on the basis of high yield.

RESEARCH NOTES

Morphological and Anatomic Characteristics on Terminal Raceme Development of Soybean Varieties with Different Stem Termination Types

JIANG Yan,WU Cun-Xiang,HU Po,HOU Wen-Sheng,ZU Wei,HAN Tian-Fu

Acta Agron Sin. 2014, 40(06):  1117-1124.  doi:10.3724/SP.J.1006.2014.01117

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Stem termination is one of the most important plant type-related traits in soybean (Glycine max [L.] Merr.). In this study, two determinate soybean varieties, Zhonghuang 13 (short terminal raceme) and Fengjiao 66-12(long terminal raceme), and an indeterminate variety Zhonghuang 24 were used to investigate the terminal raceme development processes through morphological and anatomic observations. Three soybean varieties were subjected to Beijing natural day (ND), 12 hours short day (SD) and 16 hours long day (LD) treatments, respectively. The results showed that the determinate varieties initiated the terminal racemes at 20–24 days after emergence, and the durations of the terminal raceme development were 12–16 days, which were earlier and longer than those of the indeterminate ones, respectively. Among the determinate varieties, Fengjiao 66-12 with longer terminal raceme initiated apical raceme earlier, and the differentiation was faster compared with Zhonghuang 13 with shorter terminal raceme. Beginning stage of the terminal raceme development in indeterminate variety Zhonghuang 24 was later, and the differentiation duration was shorter compared with determinate varieties. The beginning stage of the terminal raceme development was earlier, and the terminal raceme differentiation was accelerated under SD condition. Taken together, it indicated that photoperiod could affect the terminal raceme development of soybean.

Screening of a New Chemical Hybridizing Agent in Wheat

SONG Yu-Long,ZHANG Peng-Fei,ZHANG Gai-Sheng*,ZHAO Zhuo-Jun,NIU Na,ZHAO Xin-Liang,WANG Jun-Wei

Acta Agron Sin. 2014, 40(06):  1125-1131.  doi:10.3724/SP.J.1006.2014.01125

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To expand varieties of chemical hybridization agent and reduce their cost, We selected 15 varieties of chemical hybridization agent for treating wheat cultivar Xi’nong 1376 at three growth stages with four concentrations to survey the infertile effect, phytotoxicity and pollen abortion mechanism. The results showed that there were significant differences among the chemical hybridization agent treatments. At stages Feek’s 7.5 and Feek’s 9.5, abnormal vegetative growth or pollens abortion were not obvious. While at the stage of Feek’s 8.5, the rate of male sterility of Xinong 1376 was 93.33% in 0.24 kg ha^-1 T6 treatment, and the pistil and the plant showed normal development, we also achieved a high seed setting rate via crossing the male sterile plants with normal fertile lines by saturate pollination. Paraffin sections indicated that the degradable process of tapetum cells in the male sterile anther treated by T6-C was abnormal. The nucleus of tapetum cells degraded at uninucleate early stage, and then pollen nucleus degraded at uninucleate late stage. Tapetum cells, nucleus of pollen and nutrients were almost disappeared till trinucleate stage. Finally, a little residue of pollen wall left and pollen aborted. Therefore, we hypothesize that the male sterility induced by T6 could be related to the degradation of tapetum cells in anther.

Colonization of Nitrogen Fixing Bacterial Strain Klebsiella sp. DX120E Labeled with Green Fluorescent Protein (GFP) Gene within Sugarcane Plants

WEI Chun-Yan,XING Yong-Xiu,MO Yao,LIN Li,YANG Li-Tao,HU Chun-Jin，LI Yang-Rui

Acta Agron Sin. 2014, 40(06):  1132-1139.  doi:10.3724/SP.J.1006.2014.01132

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To explore the invasion patterns of N₂-fixing bacteria strain Klebsiella sp. DX120E and its colonization in sugarcane, and to determine the optimum concentrations of inoculum, we inoculated tissue culture seedlings of two sugarcane varieties (GT21 and B8) with different concentrations of Klebsiella sp. bacteria strain DX120E labeled by green fluorescent protein (GFP) gene, and with ddH₂O as CK. The results showed that the strain DX120E propagated in root, leaf sheath and leaf of sugarcane seedlings, and bacteria quantities in different parts were root > leaf sheath > leaf. There were no differences in the maximum propagation quantity under various inoculating concentrations, with the optimum concentration of 10² CFU mL^–1.Fluorescence microscope observation indicated that the bacteria could invade root through the surface cracks, generating sites of main root and lateral root, and root fracture, and intensively propagate in intercellular spaces and cells of the root, also transfer to mesophyll cells and vascular bundle sheath cells in leaf.