Table of Content

12 March 2016, Volume 42 Issue 03

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REVIEW

Dilemma and Way-out of Hybrid Rice during the Transition Period in China

PENG Shao-Bing

Acta Agron Sin. 2016, 42(03):  313-319.  doi:10.3724/SP.J.1006.2016.00313

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Hybrid rice technology is one of a few world-class technologies that were developed by Chinese scientists. Its wide adoption has made tremendous contribution to food security in China. However, the planting area to hybrid rice has started declining in recent years in China. This is because rice farmers now prefer inbred varieties with low-input requirements and cheap seed price to cut down the production cost. Hybrid rice technology is still effective in enhancing grain yield and farmers’ incoming if it is used properly. To reverse the declining trend of hybrid rice planting area in China, breeders need to adjust their breeding targets and develop new hybrid rice varieties with the following characteristics: (1) suitable for low-input and mechanized cultivation, (2) resistance to biotic and abiotic stresses, (3) high resource use efficiency, and (4) good grain quality. In addition, the cost of hybrid seed production must be reduced with low-input and mechanized cultivation technology in order to produce hybrid rice seeds which are affordable to rice farmers.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Distribution of Wheat–Rye Translocation Line T1BL•1RS in Wheat and Its Association with Fusarium Head Blight Resistance

LI Tao*,ZHENG Fei,QIN Sheng-Nan,LI Lei,GU Shi-Liang

Acta Agron Sin. 2016, 42(03):  320-329.  doi:10.3724/SP.J.1006.2016.00320

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The short arm of 1R chromosome (1RS) of rye carries resistant genes to stripe rust, leaf rust, stem rust, powdery mildew and aphids. To understand if 1RS also mediates resistance to wheat Fusarium head blight (FHB), we genotyped a panel of 192 wheat accessions from diverse geographic regions and a population of recombinant inbred lines (RIL) consisting of 184 lines developed from the cross of Ning 7840 and Chokwang by 1RS-specific molecular marker Xscm9 and evaluated FHB severities in three consecutive seasons in greenhouses using single floret inoculation method. The results demonstrated that 22 of 192 accessions carried a T1BL•1RS translocation, and the mean FHB severity (PSS) of varieties carrying T1BL•1RS translocation was significantly lower than that of lines without the translocation across the three experiments (P< 0.05), indicating 1RS may have a positive effect on reducing FHB severity. 1RS-specific marker Xscm9 and Genome in situ hybridization (GISH) showed Ning 7840 carries T1BL•1RS translocation. In the population of RILs, irrespective of Fhb1 locus, the mean PSS of lines with T1BL•1RS translocation was significantly lower than that of those lines without T1BL•1RS. The effects of Fhb1 and 1RS on FHB resistance were additive and the interactions between them were not significant (P = 0.48). The results of this study suggested that 1RS of rye most likely carries the genes resistant to FHB.

Identifying SSR Marker Locus Genotypes with Elite Combining Ability for Yield Traits in Backbone Parents of Japonica Hybrid Rice (Oryza sativa L.) in Jianghuai Area

XIE Hui,DANG Xiao-Jing,LIU Er-Bao,ZENG Si-Yuan,HONG De-Lin

Acta Agron Sin. 2016, 42(03):  330-343.  doi:10.3724/SP.J.1006.2016.00330

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Identifying marker loci related to combining ability (CA) for yield trait in parents of japonica hybrid rice facilitates improving CA of parents and enhancing standard heterosis degree of japonica rice by using molecular marker-assisted selection techniques. F₁ seeds of 90 combinations were made by hand-crossed nine CMS lines with ten restorer lines using North Carolina Design II. The F₁ populations were planted in Nanjing and Xuyi environments, and six yield traits were investigated. CA of the 19 parental lines was analyzed for six yield traits respectively using the data of 90 F₁’s. Combining the data of CA and SSR marker genotypes of the 19 parental lines, SSR marker loci related to CA for six yield traits were detected. Results showed that BT-18A and Wuqiang A were elite CMS lines, and C418 was elite restorer lines in both environments. Number of detected SSR marker loci related to CA for effective panicles per plant, spikelets per panicle, filled grains per panicle, seed setting rate, 1000-grain weight and daily yield per plant were 8, 13, 11, 6, 6, and 2, respectively in Nanjing, 12, 21, 8, 15, 10, and 7, respectively in Xuyi, and 4, 11, 5, 3, 5, and 1, respectively in both environments. Heterozygous genotype marker loci showing positive heterosis accounted for 74% (34/46) in Nanjing, and 53% (39/73) in Xuyi. Among the SSR marker loci detected in both environments, three were each co-associated with CA for three yield traits, and another three for two yield traits. The remaining 14 marker loci were each associated with CA for one yield trait. Through data-base searching, genes/QTLs for the corresponding traits were found nearly ten of the marker loci detected in both environments. Strategies of enhancing CA for yield traits of restorer lines in japonica rice using the marker loci identified in this study were discussed.

Genome-Wide Association Analysis of Height of Podding and Thickness of Pod Canopy in Brassica napus

LU Kun,WANG Teng-Yue,XU Xin-Fu,TANG Zhang-Lin,QU Cun-Ming,HE Bin,LIANG Ying,LI Jia-Na

Acta Agron Sin. 2016, 42(03):  344-352.  doi:10.3724/SP.J.1006.2016.000344

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Layer of pod canopy is an important photosynthetic and seed storage part in rapeseed, providing important contribution to yield. In this study, 412 representative Brassica napus varieties (or lines) were genotyped using the Brassica 60 K Illumina Infinium SNP array by genome-wide association analysis of the height of podding (HP) and thickness of pod canopy (TPC). A total of 16 significant SNPs were identified, including two and four SNPs associated with HP and TPC in Chongqing, each of them explained 5.61%–5.69% and 5.94%–6.31% of phenotypic variation, respectively. Five and one significant SNPs accounting for 12.66%–13.97% and 22.43% of the phenotypic variation for HP and TPC in Yunnan, respectively, were also detected. Three and one significant SNPs associated with the difference of HP and TPC between two environments were detected, explaining 17.33%–20.32% and 29.05% of phenotypic variation, respectively. The latter SNP marker was located in the same linkage disequilibrium (LD) interval with one of significant SNPs related to TPC in Chongqing. Functional annotation of genes within the LD intervals containing significant markers showed that several genes involved in regulation of cell organization and biogenesis, floral meristem development, number of silique, and multicellular organismal development existed, such as NSN1, TPST, and SAC1, which might result in the variation of HP and TPC through affecting the growth and development of flower or silique in B. napus. These loci and genes could be regarded as important candidate regions and genes for HP and TPC of B. napus. The results lay the foundation for revealing the genetic basis and molecular mechanism for podding traits, and improving the yield per unit area of B. napus.

Analysis of QTLs for Brown Planthopper Resistance in Indica Rice WD15515

DENG Zhao**,SHI Shao-Jie**,WANG Hui-Ying,SHANG-GUAN Xin-Xin,LIU Bing-Fang,JING Sheng-Li,DU Bo,CHEN Rong-Zhi,ZHU Li-Li,HE Guang-Cun*

Acta Agron Sin. 2016, 42(03):  353-360.  doi:10.3724/SP.J.1006.2016.00353

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Brownplanthopper (BPH) is one of the most destructive insect pests of rice. WD15515 is an indica germplasm highly resistant to BPH. An F₂ population was developed from the cross between 9311 and WD15515. One hundred F₂ plants were genotyped by using SSR markers and evaluated for BPH-resistance by measuring the honeydew weightsecreted by BPH(HW), the body weight increment (WB) and the body weight increment ratio (WRB). A total of four QTLs for BPH resistance were identified. The qBph2-1, based on HW(honeydew weight), was detected between RM71 and RM6911 on chromosome2, with LOD score of 3.68 and explaining the 11.08% of phenotypic variation. The qBph2-2, based on both WB and WRB, was mapped between RM6911 and RM521 on chromosome 2, with LOD score of 3.31 and 4.05 and explaining 7.81% and 9.38% of the phenotypic variation, respectively. The qBph4, based on HW, WB and WRB, was detected between RM16996 and RM17075 on chromosome 4, with LOD score of 11.11, 13.81, and 15.41 and explaining 44.38%, 45.24%, and 52.40% of the phenotypic variation, respectively. The qBph9, based on HW, WB, and WRB, was detected onchromosome 9 between RM219 and RM6444, with LOD score of 2.59,4.04, and 3.63. This locus explained 10.91%,12.39%, and 10.01% of the phenotypic variation in this population, respectively. qBph4 is amajorgene for BPH-resistance. This result provides thenew resources for BPH-resistance breeding.

Transmission and Genetic Stability of No-homoeologous Small Fragment Wheat–Haynaldia villosa Translocation Chromosomes with Pm21 in Various Cultivar Backgrounds of Common Wheat

WANG Hai-Yan,XIAO Jin,YUAN Chun-Xia,XU Tao,YU Chun-Yan,SUN Hao-Jie,CHEN Pei-Du, WANG Xiu-E*

Acta Agron Sin. 2016, 42(03):  361-367.  doi:10.3724/SP.J.1006.2016.00361

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The powdery mildew resistance gene Pm21 comes from a diploid wheat related species, Haynaldia villosa. Two Pm21-carrying small fragment translocation lines, the terminal translocation line NAU418 and the small interstitial translocation line NAU419, have been developed. Both lines are highly resistant to powdery mildew and serve as new genetic resources for improvement of disease resistance. For understanding the transmission rate of the translocation chromosomes through male and female gametes and the genetic stabilities in different wheat genetic backgrounds, the two translocations were crossed to 12 common wheat varieties from different wheat growing areas of China. The F₁ hybrids were then backcrossed as reciprocally. Chromosome configurations of the obtained F₁s were analyzed by fluorescence in situ hybridization (FISH) ofthePMC at MI. It was found that the translocation chromosomes formed rod bivalents with their corresponding wheat chromosomes. Test crosses showed that the translocation chromosomes T1AS•1AL-6VS and T4BS•4BL-6VS-4BL could be transmitted to their offspring. The transmission frequency of T1AS 1AL-6VS was higher through female gametes an average of 33.20%, ranging from 0.08% to 50.98% than through male gametes an average of 23.75%, ranging from 0.14% to 45.07%. Similarly, the transmission frequency of T4BS 4BL-6VS-4BL was higher through female gametes an average of 42.90%, ranging from 29.17% to 52.38% than through male gametes an average of 21.45%, ranging from 7.69% to 47.06%. These results show that the translocated chromosomes could be transmitted through male and female gametes, while genetic background has influences on the transmission rate, especially through male gametes.

Cloning and Deletion Analysis of GhRACK1 Promoter from Gossypium hirsutum

YANG Jiang-Tao,PANG Wei-Min,WANG Xu-Jing,Lü Shao-Pu,TANG Qiao-Ling,WANG Zhi-Xing

Acta Agron Sin. 2016, 42(03):  368-375.  doi:10.3724/SP.J.1006.2016.00368

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The absence of fiber specific promoter with future prospect is one of the main factors to restrict the development of genetic engineering in cotton fiber improvement. A 1987 bp length promoter sequence of Gossypium hirsutum GhRACK1 gene, which encodes receptor for activated C kinase 1 and precedantly expresses in fiber, was cloned by combination of inverse PCR and touchdown PCR method. Sequence analysis showed there were lots of promoter regulation elements such as Cis acting factor and the tissue specific regulation elements. The full-length GhRACK1-P and truncations from –600 to –1 bp, –1036 to –1 bp, –1260 to –1 bp and –1620 to –1 bp were obtained by PCR method. Each of the truncations was fused with gus gene and inserted into plant expression vectors pCamBIA2300. All constructs were transformed into Nicotiana tabacum var. NC89 through Agrobacterium-mediated transformation method. GUS histochemical assay showed that the full-length GhRACK1-P promoter was expressed in root and exhibited a tissue-specific expression manner. All of the truncations were expressed in root, leaf and pollen and exhibited a constitutive expression manner. Because there is the similar developmental mechanism between cotton fiber and tobacco young root or trichome, the results indicate that GhRACK1- P may be a fiber specific expression promoter.

Cloning and Expression Analysis of a Neutral/alkaline Invertase Gene (CsINV10) in Tea Plant (Camellia sinensis L. O. Kuntze)

QIAN Wen-Jun,YUE Chuan,CAO Hong-Li,HAO Xin-Yuan,WANG Lu,WANG Yu-Chun,HUANG Yu-Ting,WANG Bo,WANG Xin-Chao,XIAO Bin,YANG Ya-Jun

Acta Agron Sin. 2016, 42(03):  376-388.  doi:10.3724/SP.J.1006.2016.00376

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Based on the comprehensive RNA-Seq analysis of tea plant during cold acclimation stage, we picked out six ESTs sequences with a high similarity to neutral/alkaline invertase gene to get a splicing. As a result, a full-length of 2101 bp nucleotide sequence was obtained from tea plant after validated by using RT-PCR technique. Bioinformatics analysis showed that the sequence containing 1923 bp ORF (Open Reading Fram) and encoding 640 amino acid residues with a putative molecular mass of 71.8 kD and theoretical isoelectric point of 5.69, was named as CsINV10 (GenBank accession number: KT359348). BlastX and phylogenetic analysis indicated that the protein encoded by CsINV10 shared the highest identity (80%) with LcNI in Litchi,and had a closest genetic relationship with MeNINV8 in Manihot esculenta Crantz. Also, CsINV10 as a neutral/alkaline invertase gene could be classified into G100 family. The protein had no N-terminal signal peptide and transmembrane domain, and was predicated to be a hydrophilic protein localized in chloroplast. The expression analysis of CsINV10 under different abiotic stress conditions showed that cold, PEG and salt stresses could gradually promote the expression of CsINV10 when treated for one day, however, it had a transient increase when treated by ABA after three hours. Consequently, we speculated that CsINV10 might be involved in the tea plant response to abiotic stresses. Moreover, we found that CsINV10 had a tissue-specific expression patterns in leaf and flower. This study will provide a theoretical basis for the functional analysis of invertase genes of tea plant in response to various stresses.

Cloning of 6-SFT Gene from Leymus racemosus and Analysis of Tolerance to Drought and Cold Stresses in Transgenic Tobacco

HE Xiao-Lan,WANG Jian-Wei,LI Wen-Xu,CHEN Zhen-Zhen,ZHAO Ji-Xin,WU Jun,WANG Zhong-Hua,CHEN Xin-Hong

Acta Agron Sin. 2016, 42(03):  389-398.  doi:10.3724/SP.J.1006.2016.00389

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The fructan biosynthesis enzyme (6-SFT) plays an important role in plant responses to abiotic stresses. In this study, a full-length cDNA encoding sucrose:fructan-6-fructosyltransferase, designated as Lr-6-SFT (GenBank accession No. KT387273), was cloned from Leymus racemosus (2n = 4x = 28, NsNsXmXm) using reverse transcriptase PCR (RT-PCR) and rapid-amplification of cDNA ends (RACE) techniques. The full-length open reading frame comprises 1863 bp and encodes 620 amino acids. The predicted protein structure of the gene containes a conserved fructosyltransferase domain. Multiple sequence alignment and phylogenetic analysis showed that the Lr-6-SFT protein shared high similarity with 6-SFT proteins from Psathyrostachys huashanica, Triticum aestivum, Aegilops searsii, and Hordeum vulgare subsp. vulgare. The Lr-6-SFT gene was transferred into tobacco (Nicotiana tabacum L. cv. W38) via Agrobacterium-mediated transformation. The screened plants were tested by PCR and RT-PCR, and the transgenic tobacco plants exhibited much higher tolerance to drought and cold compared with the non-transgenic plants. Under drought and cold stresses, the Lr-6-SFT expressions were associated with the increased accumulation of stored carbohydrate and proline and the decreased malondialdehyde storage. These results suggest that Lr-6-SFT is a typical member of the glycoside hydrolase 32 (GH32) family and may be linked to enhanced tolerance to drought and cold stresses.

Isolation of blt4.9 Gene Encoding LTP Protein in Hulless Barley and Its Re-sponse to Abiotic Stresses

YAO Xiao-Hua,WU Kun-Lun*

Acta Agron Sin. 2016, 42(03):  399-406.  doi:10.3724/SP.J.1006.2016.00399

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Higher plant lipid transfer protein (LTP) is a class of small molecular weight alkaline single protein that can transfer phospholipids between biomembrane and form the biomembrane in cells. The objective of this study was to understand the function of LTP gene in hulless barley (Hordeum vulgare L. var. nudum Hook. f.). The cDNA sequence of the LTP gene, blt4.9 (GenBank accession number KU170187), was cloned from hulless barley variety Kunlun 12. The full length of blt4.9 cDNA is 720 bp including 348 bp of open reading frame and encodes 115 amino acids. The encoding product is a stable protein with a molecular weight of 11.2 kD, theoretical pI of 9.04, and instability coefficient of 28.41. This protein is rich in Gly, Ala, Leu, and Val amino acids excluding Trp, Glu, and Phe and similar to proteins encoded by other LTP genes. Sequence alignment indicated high simila­rity (98.3%) of protein encoded by blt4.9 from hulless barley and barley (Hordeum vulgare L.). The Real-time PCR assay showed that blt4.9 was up-regulated by 20–30% PEG-6000, 4ºC and 50 mmol L^-1 ABA and the expression level was higher in the most tolerant variety Handizi than in the most susceptible variety Dama, indicating a possible relationship between stress tolerance and blt4.9 in hulless barley. These results provide basic information in the utilization of LTP genes to improve hulless barley tolerance to abiotic stresses.

Ontology Construction of Crop Germplasm Resources

CHEN Li-Na,FANG Wei,SI Hai-Ping,CAO Yong-Sheng

Acta Agron Sin. 2016, 42(03):  407-414.  doi:10.3724/SP.J.1006.2016.00407

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Ontology is an efficient organization for improving integration, sharing and use efficiency of crop germplasm resources.On the basis of analyzing traditional ontology construction methods and characteristics of national crop germplasm resources, a semi-automated ontology construction method combining structured data and unstructured data was proposed. The method established initial ontology by extracting concepts and their relationship from relational database based on object-oriented approach, then,extracted concepts from unstructured web data, and enriched the semantic of these concepts using online dictionaries such as WordNet and online encyclopedia Wikipedia, so as to improve the initial ontology. Crop germplasm resources ontology modelwas constructed using Protégé, an ontology construction tool. The experimental results showed that the method made the database resources fully utilized, the complementary role of unstructured data considered, the cost of ontology construction reduced, and the ontology more perfected. The paper discussed ontology evolutionway, and pointed out the advantages and disadvantages of the study.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Leaf Photosynthetic Characteristics of Mid-season Indica Rice Varieties Applied at Different Decades

JU Cheng-Xin,TAO Jin,QIAN Xi-Yang,GU Jun-Fei,ZHANG Hao,ZHAO Bu-Hong,LIU Li-Jun,WANG Zhi-Qin,YANG Jian-Chang

Acta Agron Sin. 2016, 42(03):  415-426.  doi:10.3724/SP.J.1006.2016.00415

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The objective of this study was toinvestigate the changes in grain yield and leaf photosynthetic characteristics of mid-season indica rice varieties during their improvement. Twelve typical indica varieties (including hybrid combinations) applied in the production in Jiangsu Province during the last 70 years were used, and classified into four types of 1950–1960s, 1960–1970s, 1980–1990s and 2000–2010s (super rice) according to their application decades. The grain yield, canopy structure and leaf photosynthetic characteristics were determined. The results showed that the grain yield was progressively increased with the improvement of varieties. With the process of improvement of varieties, the total number of spikelets, leaf area index and grain-leaf ratio were markedly increased, while the leaf base angel was decreased. The improvement of varieties increased the light transmittance ratio, photosynthetic potential (green leaf area duration), net photosynthetic rate, stomatal conductance, transpiration rate, the maximum and the actual photochemical efficiency of PSII, photochemical quenching coefficient and the non-photochemical quenching coefficient of leaves from heading to maturity. The maximum leaf area index and the total photosynthetic potential during the whole growing season were very significantly correlated with grain yield. The photosynthetic rate, stomatal conductance, the maximum and the actual photochemical efficiency of PSII, photochemical quenching coefficient and the non-photochemical quenching coefficient of leaves during grain filling were significantly correlated with filled grain percentage and grain weight. The results indicate that the increase in grain yield in the processof varietal improvement is mainly attributed to the improvement in plant types and leaf photosynthetic characteristics in mid-season indica rice.

Tillering and Panicle Formation Characteristics of Machine-transplanted Early Rice and Its Parameters of Basic Population Formulae

Lü Wei-Sheng,ZENG Yong-Jun*,SHI Qing-Hua,PAN Xiao-Hua,HUANG Shan,SHANG Qing-Yin,TAN Xue-Ming,LI Mu-Ying,HU Shui-Xiu

Acta Agron Sin. 2016, 42(03):  427-436.  doi:10.3724/SP.J.1006.2016.00427

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To accurately determine planting density and make reasonably use of tillers for machine-transplanted early rice, we examined the tillering and panicle formation characteristics and the parameters related to basic population formulae with four early rice combinations (Zhuliangyou 30, Zhuliangyou 189, Zhongjiazao 17, and Jiazao 311). Results showed that the primary tillers of the machine-transplanted early rice initiated mainly from leaf 3 to leaf 6 on main stems with leaves 4 and 5 being the superior positions for tiller initiation and panicle formation. Secondary tillers initiated mainly in 1/3, 2/3, 1/4, but could not form panicles. The panicle number per seedling was 3.1 and 2.2 for hybrid rice and inbred rice, respectively. Panicles at superior leaf positions on both main stems and tillers showed better properties and higher productivity, thus making greater contributions to the yield. For hybrid rice mechanically transplanted at the stage with 3 to 4 leaves, the leaf age without tillering (bn) was 1.7 to 1.8, with the correction factor (a) of −1.2 to −1.1 and the percentage of productive tillers (r) of 0.75. For inbred rice, the bn, a, and r were 2.5 to 2.7, −1.3 to −1.1, and 0.7, respectively. In conclusion, in order to obtain a high yield of machine-transplanted early rice, the key strategy is to ensure a sufficient number of basic seedlings, and promote tillering as early and many as possible, whereby increasing the percentage of productive tillers.

Effects of Silicon Fertilizer Rate on Grain Yield and Related morphological and Physiological Characteristics in Super Rice of Yongyou Japonica/indica Hybrids Series

WEI Huan-He,MENG Tian-Yao,LI Chao,ZHANG Hong-Cheng,SHI Tian-Yu,MA Rong-Rong,WANG Xiao-Yan,YANG Jun-Wen,DAI Qi-Gen,HUO Zhong-Yang,XU Ke,WEI Hai-Yan,GUO Bao-Wei

Acta Agron Sin. 2016, 42(03):  437-445.  doi:10.3724/SP.J.1006.2016.00437

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A field experiment was conducted using Yongyou 12 and Yongyou 15 with five treatments of 0, 75, 150, 225, and 300 kg ha^-1 silicon application. Results indicated that grain yield of Yongyou 12 and Yongyou 15 increased firstly and then decreased with increase of the silicon application rate. The highest grain yield of both Yongyou 12 and Yongyou 15 achieved at the silicon rate of 225 kg ha^-1. Analysis on yield components showed that number of panicles of Yongyou 12 and Yongyou 15 increased with the increase of silicon application rate, while 1000-grain weight and seed-setting rate were both decreased with the increased silicon application rate. With the increase of silicon application rate, number of tillers and stems of Yongyou 12 and Yongyou 15 at jointing, heading, and maturity stages increased synchronously. Panicle rate of Yongyou 12 and Yongyou 15 increased firstly and then decreased with the increase of silicon application rate, and the peak value was at the silicon rate of 225 kg ha^-1. With the increase of silicon application rate, dry matter weight and leaf area index at jointing, heading, and maturity stages as well as dry matter accumulation and leaf area duration from jointing to heading and from heading to maturity increased. With the increase of silicon application rate, leaf length and leaf width of the 1st leaf, 2nd leaf, and 3rd leaf of Yongyou 12 and Yongyou 15 increased synchronously, while leaf basal angle and dropping angle of the 1st leaf, 2nd leaf, and 3rd leaf of Yongyou 12 and Yongyou 15 decreased synchronously. Moreover, compared with check (0 kg ha^-1), silicon application significantly increased dry matter per stem, per sheath, and per length of stem. At last, the technology on the effective application of silicon was discussed.

Effects of Postponing Nitrogen Topdressing on Water Use Characteristics of Maize-Pea Intercropping System

TENG Yuan-Yuan**,ZHAO Cai**,CHAI Qiang*,HU Fa-Long,FENG Fu-Xue

Acta Agron Sin. 2016, 42(03):  446-455.  doi:10.3724/SP.J.1006.2016.00446

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In oasis irrigation agricultural region, water resources deficit is one of the most penetrating constraints for developing intercropping. However, these was neither sufficient academic basis for enhancing water utilization rate through optimizing chemical nitrogen application, nor available practices for increasing yield and water use efficiency (WUE) of crops in developing cereal/legume intercropping. Here, we carried out a field experiment in Hexi Corridor, a typical arid oasis irrigation area in 2012-2013, and the effect of postponing nitrogen topdressing on yield and water use characteristics of sole- and intercropping maize, pea systems was investigated. The total nitrogen application level for the same cropping system was equal. On the basis of 10% basal N fertilizer plus 50% pre-tasseling N fertilizer, three N treatment were managed with different topdressing amounts postponed: N₁, N postponing application with 30%; N₂, N postponing application with 15%; and N₃, traditional nitrogen application. The purpose of the study focused on providing academic and practical evidence for increasing yield and WUE through optimizing nitrogen fertilizer management. The results showed that, N postponing application had no significant influence on total water consumption (ET) of maize-pea intercropping in the whole growing stage, but the soil evaporation (E) and E/ET were significantly decreased. As compared with traditional nitrogen application treatment, evaporation and E/ET in 15% N postponing application maize-pea intercropping were reduced by 6% and 4%, respectively, while those in maize-pea intercropping with 30% N postponing application both by 2%. In maize-pea intercropping systems, average soil evaporation in pea strips was 329 mm, but that in maize strips was 232 mm, showing that invalid water consumption in pea strip is significantly higher than that in maize strips. 15% N postponing application (topdressing fertilizer with 67.5 kg N ha^-1 at pea flower pod period/maize jointing period, topdressing fertilizer with 225 kg N ha^-1 at maize pre-tasseling period and topdressing fertilizer with 112.5 kg N ha^-1 at maize 15 d after flowering period) combined with maize-pea intercropping could be one of the effective strategies to promote grain yield and WUE of cereal-legume intercropping in Oasis irrigation region. Mixed grain yield of maize-pea intercropping under N postponing application with 15% was 6% higher than that of the traditional nitrogen application treatment. And WUE of pea-maize intercropping systems was also significantly higher than that of the traditional nitrogen by 5%. As well as mixed grain yield and WUE of pea-maize intercropping under N postponing application with 30% was 3% and 2% higher than that of the traditional nitrogen application treatment respectively. Consequently, the

SCIENTIFIC WRITING

How to Prepare Figures in Articles of Molecular Biology?

XIAO Yang,ZHANG Hong,YU Xiang-Hong,LI Hong-Dan,YUAN Huan-Huan,SU Liang,SUN Lei,YANG Zong-Ju,YANG Jian-Ping

Acta Agron Sin. 2016, 42(03):  456-465.  doi:10.3724/SP.J.1006.2016.00456

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Proper figures are beneficial to our article presentation. In this article, we introduced some essential skills of figure preparation in articles of molecular biology using Excel and Photoshop softwares. Excel is an effective software not only for presentation of our experiment data, but also help us to make the finishing point when using different infilling colors and textures to aggrandize visual effects in Excel histogram. When processing figures of structure and immunoblot result, it can give prominence to subject through excision, enlargement, and adjustment of contrast and brightness using Photoshop software. When the strength of GFP fluorescence and GUS staining needs to be compared in different backgrounds, it is necessary to piece and adjust figures together as a whole one.