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Table of Content

    12 May 2019, Volume 45 Issue 5
    • CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
      Genome-wide screening and evaluation of SNP core loci for fingerprinting construction of cotton accessions (G. barbadense)
      Le-Chen LI,Guo-Zhong ZHU,Xiu-Juan SU,Wang-Zhen GUO
      Acta Agronomica Sinica. 2019, 45(5):  647-655.  doi:10.3724/SP.J.1006.2019.84123
      Abstract ( 802 )   HTML ( 44 )   PDF (1603KB) ( 319 )   Save
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      Sea-island cotton (G. barbadense), characterized by its extra-long staple (ELS), strong and fine fibers, and disease resistance, provides important natural fiber for textile industry, also key donor for improving agronomic traits of upland cotton. However, compared to G. hirsutum, there are few studies on genetic diversity and genotyping in G. barbadense. To obtain the SNP core loci for fingerprinting construction of sea-island cotton accessions, we performed SNP genotyping within 282 accessions using the CottonSNP80K array. A total of 2594 high-quality SNP loci were obtained based on the selective criteria of call frequency for each locus > 0.95, loci with polymorphism, minor allele frequency (MAF) > 0.01, heterozygosity rate < 0.05, and the removal of same genotype. Further, the number of optimized core loci was screened by gradients analysis. With the number of loci increasing, the discrimination ability of the sea-island cotton accessions increased gradually. When the loci were 200, the recognition rate was 89%, and when the number of the loci increased to 1500, the recognition rate was 99%. When the loci were further increased, no significantly improved recognition rate was detected. Based on the detection using the 1500 core loci combination, the average MAF value was 0.14, the average heterozygosity rate was 0.007, and the average polymorphism information content was 0.21. The polyacrylamide gel electrophoresis for the core SNP loci verified the consistency as high as 98.3% between SNP-PCR and chip genotyping. This study provides a set of core SNP loci suitable for constructing fingerprinting of sea-island cotton accessions, which can be used for genetic diversity analysis and fingerprinting identification of sea-island cotton.

      Genetic analysis and causal gene identification of maize viviparous mutant vp-like8
      Rui WANG,Yang-Song CHEN,Ming-Hao SUN,Xiu-Yan ZHANG,Yi-Cong DU,Jun ZHENG
      Acta Agronomica Sinica. 2019, 45(5):  656-661.  doi:10.3724/SP.J.1006.2019.83058
      Abstract ( 787 )   HTML ( 36 )   PDF (1820KB) ( 260 )   Save
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      The maize mutant vp-like8 shows clear viviparous phenotype and stable inheritance, and genetic analysis showed that the mutant phenotype was controlled by a single recessive gene. Using an F2 segregation population derived from vp-like8 and inbred line Zheng 58, the causal gene was mapped to an interval from 160.4 Mb to 165.6 Mb on chromosome 3 by the BSR-Seq technology. According to the maize genomic database, a previously discovered viviparous gene Vp1 was identified to be in this mapping interval. The test crosses from vp1 and vp-like8 heterozygous plants showed a 3:1 segregation ratio between normal and viviparous kernels. The genomic sequence analysis revealed that vp-like8 mutant had a 343 bp deletion in the second intron and 222 bp insertion in the third intron of Vp1 gene, which is different from vp1 mutation of an only 343 bp deletion in the second intron of Vp1 gene. Further real time PCR analysis revealed that, compared with the normal kernels, the transcript level of Vp1 was significantly decreased both in vp-like8 and vp1 viviparous kernels. Taken together, these evidences suggest that vp-like8 is a new allele mutant of Vp1.

      Phenotypic identification and gene mapping of temperature-sensitive green- revertible albino mutant tsa2 in rice (Oryza sativa L.)
      Li-Na SHANG,Xin-Long CHEN,Sheng-Nan MI,Gang WEI,Ling WANG,Ya-Yi ZHANG,Ting LEI,Yong-Xin LIN,Lan-Jie HUANG,Mei-Dan ZHU,Nan WANG
      Acta Agronomica Sinica. 2019, 45(5):  662-675.  doi:10.3724/SP.J.1006.2019.82049
      Abstract ( 686 )   HTML ( 19 )   PDF (5099KB) ( 338 )   Save
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      Temperature-sensitive leaf color mutants of rice are ideal materials in studies on photosynthesis, chloroplast structure and function, and chloroplast development. A temperature-sensitive green-revertible albino mutant (tsa2) with genetically stable mutational traits was screened out from the progeny of ethyl methane sulfonate (EMS) treated indica three-line maintainer line Xinong 1B. The wild type seedlings had normal phenotype at 22°C, while the mutant tsa2 had completely albino leaves and about 40% of albino seedlings died at the seedling stage; the photosynthetic pigment contents and photosynthetic rate of surviving albino seedlings decreased significantly, and the main agronomic traits were significantly lower than those of the wild type at maturity stage. When germinated at 28°C, tsa2 showed light-green leaves with white streaks and significantly lower photosynthetic pigment contents than the wild type, while a small difference of photosynthetic rate and main agronomic traits between the tsa2 and the wild type. No significant difference in leaves was observed between tsa2 and the wild type when seedlings germinated at 32°C. Transmission electron microscope observation revealed that the albino leaves of tsa2 demonstrated abnormal chloroplast development (without differentiated grana and granum lamella) or without chloroplast at 22°C and completely developed chloroplasts in partial mesophyll cells at 28°C, and normal number and morphology of mesophyll cells compared with wild type at 32°C. The analysis of qRT-PCR indicated that genes related to partial photosynthetic pigment metabolism pathways, chloroplast development and photosynthesis expressed in tsa2 to a varying degrees compared with these of the wild type. Genetic analysis suggested that mutational phenotype of tsa2 was controlled by a single recessive nuclear gene, TSA2, which was finally mapped between SSR markers S5-57 and S5-119 on chromosome 5, with a physical distance of 718 kb. These results lay a foundation for the research on genetic improvement and the mechanism explanation of chloroplast development affected by temperature in rice (Oryza sativa L.).

      Stability of major fatty acids contents of peanut varieties grown in different ecological regions
      Jian-Bin GUO,Bei WU,Wei-Gang CHEN,Li HUANG,Yu-Ning CHEN,Xiao-Jing ZHOU,Huai-Yong LUO,Nian LIU,Xiao-Ping REN,Hui-Fang JIANG
      Acta Agronomica Sinica. 2019, 45(5):  676-682.  doi:10.3724/SP.J.1006.2019.84132
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      Peanut is an important oil crop, and its fatty acids contents were not stable due to different environments grown. In this study, 60 peanut varieties including six accessions with high oleic acid and 54 accessions with normal oleic acid widely grown in Huanghuai and Yangtze river areas were planted in four ecological regions of Wuhan, Shijiazhuang, Puyang, and Zhoukou in 2016-2017. After harvesting, the dried mature seeds were tested for fatty acid content according to the method in GB/T 5510-2011. The content of oleic acid in peanut varieties with high oleic was more stable than that with normal oleic acid. However, the contents of palmitic and linoleic acids were more stable in normal oleic acid varieties than in high oleic acid cultivars. Regarding the effect of environment grown on the fatty acids, the content of oleic acid of cultivars grown in Wuhan was higher than that grown in other regions in the present study, with the average of 52.93% and 52.64% in the two years. Comparing the fatty acid composition between high oleic varieties and normal oleic varieties, the arachidonic acid content was significantly increased by 54.10%, besides the significant increase of oleic acid content in high oleic varieties. However, the palmitic and linoleic acids were much less in high oleic varieties than in normal oleic varieties, reduced by 45.20% and 90.44% respectively. Combined with the diversity of the 60 varieties by SSR technique previously, the six high oleic acid varieties should be in different groups (G1, G2c, and G2e), showing considerable large genetic variations. These results from the present study provide a basis for the reasonable planting layout and further genetic improvement of peanut varieties.

      Creation and analysis of marker free transgenic soybean germplasm with low phosphate tolerance transcription factor GmPTF1 based on Cre/loxP system
      Xiao-Fang ZHANG,Qiu-Ping DONG,Xiao QIAO,Ya-Ke QIAO,Bing-Bing WANG,Kai ZHANG,Gui-Lan LI
      Acta Agronomica Sinica. 2019, 45(5):  683-692.  doi:10.3724/SP.J.1006.2019.84118
      Abstract ( 522 )   HTML ( 10 )   PDF (770KB) ( 158 )   Save
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      The screening marker genes in transgenic crops have potential safety risks, which are necessarily eliminated in the improvement of transgenic plants. The transcription factor PTF1 has the effect improving phosphorus uptake by plants under low phosphorus stress. So Cre/loxP-GmPTF1 was transferred into soybean cultivar Yudou 22 [Glycine max (L.) Merr.] via Agrobacterium-mediated cotyledonary node transformation method. And then, the marker-free transgenic soybean with GmPTF1 was obtained by means of induced Cre/loxP site specific recombination with β-estradiol. After the marker gene was deleted, the recombinant sequences were amplified by PCR and then sequenced. The sequencing results indicate that the marker genes were completely deleted out of the transgenic soybean genome. The recombinant maintained with correct ORF correct target gene sequence, and a new splicing type appeared in loxP recombination. Two loxP sequences were missing in the recombination. The length of the new recombinant in splicing site was 38 bp which was no homology with other sequences in NCBI database. And the recombination was involved in the flank sequence outside the two loxP sites, which lead partially deleted in the outer flank sequences of Cre/loxP cassette. The results of RT-PCR and Western blot showed that GmPTF1 could be transcribed and translated normally in marker-free transgenic soybean plants. The expression level of GmPTF1 in roots, stem and leaves was higher than that in wild type, which was not significantly different in seeds. in the sand culture experiment under low phosphorus condition, the root indexes, dry biomass, chlorophyll content and phosphorus content in marker-free transgenic soybean were significantly higher than there in the wild type, while the MDA content was lower than that in the control. We conclude that screening marker genes in transgenic soybean could be effectively deleted by Cre/loxP recombinant system.

      Analysis of drought resistance and DNA methylation level of resynthesized Brassica napus
      Yi YUAN,Shuang ZHU,Ting-Ting FANG,Jin-Jin JIANG,You-Ping WANG
      Acta Agronomica Sinica. 2019, 45(5):  693-704.  doi:10.3724/SP.J.1006.2019.84120
      Abstract ( 438 )   HTML ( 16 )   PDF (1343KB) ( 172 )   Save
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      Brassica napus, as one of the important resources of edible plant oil and forage protein, is a polyploid species with great economic value. However, it is sensitive to drought stress throughout whole lifecycle due to short domestication history and narrow genetic background. Thus, it is a main purpose to breed B. napus cultivar with high yield and drought resistance. In the present study, we compared the drought resistance among S1-S4 generations of resynthesized B. napus and diploid parents under different time periods of 15% PEG-6000 treatment. The different drought tolerance levels were assessed based on phenotype observation, leaf physiological indexes (MDA, soluble protein, SOD and POD). Accompanying with water content analysis, we found the drought tolerance showed a trend of B. oleracea > Bn-S3 > Bn-S4 > Bn-S1 > Bn-S2 > B. rapa. Under drought stress, POD and SOD activities in Bn-S3 and Bn-S4 were higher than these in other plants tested, and MDA content was decreased, indicating that Bn-S3 and Bn-S4 have better ability in clearing ROS, and defending from peroxidation damage. On the basis of HPLC analysis, the methylation level in all materials was the highest under drought stress of 12 h. And the methylation level in B. rapa was higher than that in others, that in Bn-S1 and Bn-S4 was between that in parents, while that in Bn-S2 and Bn-S3 was lower than that in parents. Methylation sensitive amplification polymorphism analysis also revealed multiple changes in methylation and demethylation level of resynthesized B. napus under drought stress, indicating methylation changes might be involved in plant drought tolerance.

      Comparative analysis on flower bud differentiation of multilocular and bilocular traits in Brassica juncea
      Xin LI,Lu XIAO,Lin-Fang LI,De-Zhi DU
      Acta Agronomica Sinica. 2019, 45(5):  705-713.  doi:10.3724/SP.J.1006.2019.84121
      Abstract ( 446 )   HTML ( 5 )   PDF (9036KB) ( 144 )   Save
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      Brassica juncea, possessing natural multilocular traits compared with bilocular rapeseed (two-chambered), has high yielding potential due to multiple locules (3-5 locules) and multi-grains. To disclose the formation process of multilocular traits, we constructed a BC3F5 population from a cross between Qinghai multilocular rapeseed and Tayou 2 (two locules) to analyse the whole process of flower bud differentiation of homozygous bilocular plants and multilocular plants through paraffin section along with scanning electron-microscopy observation. The flower bud differentiation in multilocular rapeseed took place at about 22 days after seedling emergence, with an average leaf number of 5, and whole differentiation was divided into five stages. The diameters of shoot apical meristem (SAM) and floral meristem (FM) in multilocular plants were significantly larger than these in bilocular plants. The center of growing cone of the multilocular was deeply recessed into an “X” shaped region with four carpels, while that of the bilocular into an “I” shape, forming half and half regions with two carpels, such differentiation could affect the number of carpels and seeds rows. The tip of the stigma also formed “I” and “X” shapes, which could be used as an indicator, to distinguish between multilocular plants and bilocular plants in the early stage.

      TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY
      Effects of straw strip mulching on furrows and planting in ridges on water use efficiency and tuber yield in dryland potato
      Yu-Zhang CHEN,Hui-Hui TIAN,Ya-Wei LI,Yu-Wei CHAI,Rui LI,Hong-Bo CHENG,Lei CHANG,Shou-Xi CHAI
      Acta Agronomica Sinica. 2019, 45(5):  714-727.  doi:10.3724/SP.J.1006.2019.84097
      Abstract ( 532 )   HTML ( 16 )   PDF (1390KB) ( 259 )   Save
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      Field experiments were conducted to study the effects of different mulching materials and ridge-furrow widths on potato (Solanum tuberosum L.) growth, tuber yield, soil moisture and water use efficiency in a semiarid rain-fed ecosystem in northwest China in 2016 and 2017. Four treatments were performed: (1) alternating narrow furrows and wide ridges with corn straw strip mulching only on narrow furrows and planting in the wide ridges (RFWN); (2) alternating micro-ridge-furrows with corn straw strip mulching only on furrows and planting in the ridges (RFN); (3) alternating small and large ridges full mulching with black plastic film and planting in the large ridges (RFB), and (4) traditional-flat planting without mulching (CK). Compared with CK, mulching treatments significantly decreased total evapotranspiration by 6.1%-13.2%, increased average soil water content (1.2-1.8 m depth) by 7.6% at tuber initiation stage, and RFB treatment significantly increased soil water content (0-0.2 m) by 30.3% at starch accumulation stage in the dry year of 2016. In the normal precipitation year of 2017, the total evapotranspiration in RFB was 22.2% lower than that in CK, and there was no significant difference in total evapotranspiration observed among the RFWN, RFN and CK treatments. The average soil water content (0-2 m depth) in mulching treatments was 8.7%, 13.0%, and 13.1% higher than that in CK, respectively, at tuber initiation, tuber bulking and starch accumulation stage in 2017. Compared with CK, mulching treatments significantly increased soil water storage (0-2 m), weight of dry matter per plant and final plant height by 5.4%-15.5%, 12.8%-147.4%, and 21.1-39.7 cm, respectively, and thus enhanced tuber yield and water use efficiency by 51.6%-88.2% and 68.2%-111.7% in both years, respectively. The tuber yield, water use efficiency and net income for RFN treatment was the highest increasing on average by 87.8%, 97.5%, and 254.2%, respectively, in both years. In addition, RFN had the advantages of simple operation, the environmentally friendly and the highest input/output ratio compared with the treatment of plastic film mulching. Hence, RFN is the best cultivation model for dryland potato.

      Responses of photosynthetic characteristics to low light stress in ear leaves of high photosynthetic efficiency maize at narrow row of maize-soybean strip intercropping system
      Yong-Fu REN,Guo-Peng CHEN,Tian PU,Cheng CHEN,Jin-Xi ZENG,Xiao PENG,Yan-Wei MA,Wen-Yu YANG,Xiao-Chun WANG
      Acta Agronomica Sinica. 2019, 45(5):  728-739.  doi:10.3724/SP.J.1006.2019.83040
      Abstract ( 746 )   HTML ( 11 )   PDF (2650KB) ( 288 )   Save
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      The photosynthesis of maize is inhibited in narrow row under maize-soybean relay strip intercropping system. In order to explore the internal mechanisms of photosynthesis characteristics responding to low light stress in ear leaf of intercropped maize cultivars with high photosynthetic efficiency, the low (A1: Zhongwangyu 18), middle (A2: Chuandan 418), and high (A3: Rongyu 1210) photosynthetic efficiency maize varieties were grown in maize-soybean strip intercropping system (two rows of maize intercropped with two rows of soybean) with different narrow spaces (B1: 20 cm; B2: 40 cm; B3: monoculture). The photosynthetic rate and PEPCase activity of “Rongyu 1210” were significantly higher than those of “Zhongwangyu 18” and “Chuandan 418”, respectively under the conventional row spacing (40 cm) and low light intensity conditions (before 10 a.m., after 4 p.m.). Additionally, “Rongyu 1210” had more complete chloroplast structure, which might result in lower initial fluorescence (Fo) and maximum fluorescence (Fm) of chlorophyll compared with “Zhongwangyu 18” and “Chuandan 418”. The Pn and activities of key enzymes decreased, but the initial fluorescence (Fo), maximum fluorescence (Fm) and effective photochemical quantum yield (Fv'/Fm') of chlorophyll increased with the decreasing narrow row spacing, Interestingly, the above indexes of “Rongyu 1210” were stable under the variable light environment. The photosynthetic rate, photosynthetic key enzyme activities, and yield of “Rongyu 1210” between monoculture and intercropping were not significantly different. However, the photosynthetic rate and PEPCase activity of “Zhongwangyu 18” and “Chuandan 418” in intercropping decreased by 28.9%, 24.2% and 7.4%, 5.5% compared with that in monoculture, respectively. In conclusion, the response of maize varieties to shade conditions in narrow row under intercropping system is different. Rongyu 1210, with a positive responding, that has better physiological indexes in photosynthesis than the other two maize varieties in the intercropping system. These results provide a theoretical explanation for excellent adaptability to the lower light environment and high yield in Rongyu 1210 under maize-soybean intercropping strip system.

      Effects of different soil tillage systems on physiological characteristics and yield of double-cropping rice
      Hai-Ming TANG,Xiao-Ping XIAO,Chao LI,Wen-Guang TANG,Li-Jun GUO,Ke WANG,Kai-Kai CHENG,Xiao-Chen PAN,Gen SUN
      Acta Agronomica Sinica. 2019, 45(5):  740-754.  doi:10.3724/SP.J.1006.2019.82030
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      In order to explore the effects of different soil tillage systems on physiological characteristics, dry matter accumulation and grain yield, a fixed location field experiment was conducted using early and late double-cropping rice and Chinese milk vetch (Astragalus sinicus L.) system with four soil tillage treatments including conventional tillage with residue incorporation (CT), rotary tillage with residue incorporation (RT), no-tillage with residue retention (NT), and rotary tillage with residue removed as control (RTO) from 2016 to 2017. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in leaves of CT, RT treatments were increased as compared with those of RTO treatment at different main growth stages of early and late rice. Meanwhile, malondialdehyde (MDA) contents in leaves of CT and RT treatments were decreased. At different main growth stages of early and late rice, the activities of SOD, POD, and CAT in leaves of CT and RT treatments were significantly higher than those of RTO treatment (P<0.05), while MDA contents of CT and RT treatments were significantly lower than those of RTO treatment (P<0.05). Meanwhile, the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) in leaves of CT treatment were significantly higher than those of RTO treatment (P < 0.05), showing an order of CT > RT > NT > RTO. The results also indicated that the total dry matter accumulation of early and late rice were increased, and its reasonable distribution of rice plant in CT and RT treatments. In 2016 and 2017, the grain yield of early and late rice in CT treatment was significantly higher than that in RTO treatment (P<0.05), with an increase of 731.1-733.3 kg ha -1 and 582.5-717.6 kg ha -1, respectively. As a result, it is an effective way for improving protective enzyme activities and photosynthetic characteristics in leaves, dry matter accumulation of rice by conventional tillage and rotational tillage combined with residue incorporation practices, which results in higher grain yield of rice.

      Response mechanism of sweet potato storage root formation and bulking to soil compaction and its relationship with yield
      Wen-Qing SHI,Bin-Bin ZHANG,Hong-Juan LIU,Qing-Xin ZHAO,Chun-Yu SHI,Xin-Jian WANG,Cheng-Cheng SI
      Acta Agronomica Sinica. 2019, 45(5):  755-763.  doi:10.3724/SP.J.1006.2019.84084
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      Field experiments were performed using two sweet potato [Ipomoea batatas L. (Lam.)].cultivars (‘Beijing 553’ and ‘Longshu 9’) with significant differences in source sink characteristics. The physiological and ecological mechanisms of regulation of soil compaction on storage root yield were studied under different soil compaction treatments. The non-capillary porosity of plough horizon increased significantly during the whole growth period with the decrease of soil compactness. During storage root formation (20-40 d), the minimum temperature was significantly decreased, the maximum temperature and diurnal temperature range of plough layer were significantly increased with the decrease of soil compactness. Compared with the control, the loose treatment could increase the activities of sucrose synthase (SS) and adenosine diphosphate glucose pyrophosphorylase (ADPGPPase) in storage roots, also the starch content, the initial dry matter accumulation potential, dry matter accumulation rate and the distribution ratio of 13C assimilates from functional leaf to storage root. At harvest period the average weight per storage root and harvest index were significantly increased in the loose treatment, Beijing 553 and Longshu 9 increased production by 20.01% to 24.25% and 21.64% to 27.78%, respectively.

      Effects of top dressing with reduced nitrogen fertilizer and density enhancement on water use efficiency and growth of potatoes planted in mini-ditch on ridges with plastic mulching
      Xian-Feng YU,Xu-Cheng ZHANG,Yan-Jie FANG,Guang-Rong CHEN,Hong-Li WANG,Hui-Zhi HOU,Yi-Fan MA,Ji-Jun ZHAO
      Acta Agronomica Sinica. 2019, 45(5):  764-776.  doi:10.3724/SP.J.1006.2019.84014
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      The optimization of ridge-furrow construction, plant density and fertilizer application are three promising ways to increase rainwater use efficiency, crop yield and water use efficiency. A long-term field experiment was carried out in semi-arid area of northwestern China from 2015 to 2017, using potatoes planted in mini-ditch on ridges with plastic mulching, to explore the effects of fertilizer application and plant density on soil temperature, water consumption at different growth stages, yield and water use efficiency. Two plant densities (low density of 49,500 plants ha -1, and high density of 64,500 plants ha -1) and three fertilization methods (traditional fertilizer application, PM; reduced chemical fertilizer dressing, PMN; and organic fertilizer substitution, PMO) were set up as treatments, using randomized block design with three replications. The high density did not affect soil temperature, SPAD values and yield significantly, but lowered water consumption in pre-flowering stage, above-ground biomass per plant, and water use efficiency. However, LAI and water consumption were improved in post-flowering stage. Compared with low density treatments, LAI in high density increased by 3.64%-15.01%, and water consumption in tuber bulking period increased by 6.50%-48.52%. Both PMN and PMO increased soil temperature in pre-flowering stage, potato foliar SPAD and LAI from squaring to tuber bulking stage, compared with PM. For example, LAI increased by 10.42%-44.26% at flowering stage. PMN and PMO decreased water consumption during pre-flowering period, but increased it during post-flowering period, resulting in a 6.95%-49.85% increment in aboveground biomass at bulking stage. On average, PMN increased potato tuber yield and WUE under low density by 9.96%-20.87% and 13.64%-17.61%, 5.46%-20.81% and 13.25%-45.24%, respectively, compared with PM and PMO. Consequently, the increment of plant density did not affect potato tuber yield and WUE. However, PMN and PMO promoted potato water utilization in post-flowering period and increased LAI, resulting in significant increment of potato tuber yield and WUE, showing an efficient way for fertilization management of potato in semiarid loess plateau of northwestern China.

      Responses of maize growth and yield to nitrogen application in dryland under different precipitation conditions
      Fang NING,Yuan-Hong ZHANG,Peng-Fei WEN,Rui WANG,Qian WANG,Zhao-Yang DONG,Guang-Can JIA,Jun LI
      Acta Agronomica Sinica. 2019, 45(5):  777-791.  doi:10.3724/SP.J.1006.2019.83055
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      Water deficiency is a main limiting factor for maize growth in dryland. The seasonal fluctuation of precipitation and the frequent occurrence of drought have severely affected the normal growth and stable production of spring maize in Weibei dryland. An in-situ experiment was conducted in Heyang county located in Weibei dryland from 2016 to 2018, with five treatments of nitrogen rates, including 0 kg ha -1 (N0), 75 kg ha -1 (N75), 150 kg ha -1 (N150), 270 kg ha -1 (N270), and 360 kg ha -1 (N360) from 2016 to 2017 and 0 kg ha -1 (N0), 90 kg ha -1 (N90), 180 kg ha -1 (N180), 270 kg ha -1 (N270), and 360 kg ha -1 (N360) in 2018, using two spring maize varieties Zhengdan 958 (ZD958) and Shaandan 8806 (SD8806). The effects of nitrogen application rates on dynamic changes of soil moisture, dry matter accumulation, yield composition, economic returns and water use efficiency (WUE) of spring maize during growth period were analyzed in different test years. There were two distribution types of precipitation in the test years, one was rainy at the ear stage and droughty at the grain stage (2016, 2018), while the other was droughty at the ear stage and rainy at the grain stage (2017). Precipitation amount and its distribution in the growing season significantly affected soil water storage and aboveground dry matter accumulation of maize, thus affecting grain yield and its components. Drought at the ear stage significantly reduced aboveground dry matter accumulation and kernel number per ear, while drought in the grain stage decreased kernel weight. The yield of applying nitrogen fertilizer treatment was 6.72%-91.23% higher than that of N0 across three years. The effects of nitrogen rates on grain yield and WUE followed a quadratic curve relationship. In the case of being rainy at the ear stage and droughty at the grain stage there occurred the highest grain yield and WUE in N270, in contrast when it was droughty at the ear stage and rainy at the grain stage, spring maize performed better in N150 treatment. The Grain yield was positively correlated with “precipitation from fallow to tasseling” (FP2) and “the sum of soil water storage before sowing and precipitation from sowing to tasseling” (SP2) (FP2: R 2=0.839 **; SP2: R 2=0.837 **). Based on a comprehensive assessment for grain yield, WUE and net economic returns, the optimum nitrogen application rate in this study is basic fertilizer of 150 kg ha -1 plus top dressing of nitrogen fertilizer in time according to the predicted yield, which is estimated by FP2 or SP2, so as to get the optimized N fertilizer amount and maximized yield, WUE and economic returns in Weibei dryland.

      RESEARCH NOTES
      Repetitive intense flashes inhibit photosystem II activity and thermal dissipation in cotton leaves
      Han-Yu WU,Fei XIAO,Ya-Li ZHANG,Chuang-Dao JIANG,Wang-Feng ZHANG
      Acta Agronomica Sinica. 2019, 45(5):  792-797.  doi:10.3724/SP.J.1006.2019.84104
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      Not only continuous high light results in the decrease of photosynthetic efficiency, but also intense flashes may affect the photosynthetic function. In this study, cotton (Gossypium hirsutum L.) cultivar Xinluzao 45 was used to investigate the effects of repetitive intense flash treatment (leaves exposed to 20,000 μmol m -2 s -1 for 300 ms, with interval time of 10 s, and the whole treatment duration was 30 min) on two photosystems and photosynthetic function of cotton leaves. Chlorophyll fluorescence, P700 and gas exchange were measured before and after repetitive intense flash treatment, respectively. The content of active PSI (photosystem I) reaction center and the electron transfer activity of PSII (photosystem II) all decreased after repetitive intense flash treatment which reflected by the significant increase in J and K phases of the fluorescence induction kinetics curves after repetitive intense flash treatment. ΦND (the quantum yield of non-photochemical energy dissipation due to donor side limitation) of PSI decreased while ΦNA (the quantum yield of non-photochemical energy dissipation due to acceptor side limitation) increased, indicating that acceptor side of PSI was primarily inhibited by repetitive intense flashes. Repetitive intense flash treatment induced a distinct decrease in the quantum yield of PSII in cotton leaves under actinic light. Moreover, ΦNPQ (the quantum yield of regulated energy dissipation) of PSII decreased significantly after repetitive intense flash treatment. However, ΦNO (the quantum yield of non-regulated energy dissipation) increased considerably, demonstrating that the repetitive intense flashes caused PSII photoinhibition. The photosynthetic rate and the stomatal conductance decreased while the intercellular CO2 concentration increased after repetitive intense flash treatment, indicating that the reduction of carbon assimilation induced by repetitive intense flash treatment is not limited by stomata. Therefore, we believe that the repetitive intense flash treatment not only induces inactivation of PSI, but also leads to PSII photoinhibition and the decrease of thermal dissipation. The suppression of photosynthetic electron transport activity may play important role in the decrease of photosynthetic rate after repetitive intense flash treatment.

      Screening and comprehensive evaluation of aluminum-toxicity tolerance during germination stage in 52 varieties (lines) of pea germplasm
      Cui CUI,Chuang CHENG,Yu-Feng ZHAO,Huan-Huan GAO,Rui-Li WANG,Liu-Yan WANG,Qing-Yuan ZHOU
      Acta Agronomica Sinica. 2019, 45(5):  798-805.  doi:10.3724/SP.J.1006.2019.84110
      Abstract ( 395 )   HTML ( 19 )   PDF (421KB) ( 151 )   Save
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      With increasing acidification of soil, aluminum toxicity has become one of the important stress factors affecting seed germination quality and crop yield. The purpose of this study is to explore the characteristics of aluminum toxicity tolerance in different genotypes of Pisum sativum, and establish the comprehensive evaluation system for screening and breeding new varieties with aluminum toxicity tolerance. The identification of tolerance at germination stage was performed according to the comprehensive tolerance coefficient of aluminum toxicity (CAC) value, the average subordinate function value (ASF value), the comprehensive evaluation value of aluminum toxicity tolerance (A-value) in correlation analysis, frequency analysis, principal component analysis, cluster analysis and stepwise regression analysis. Fifty-two pea varieties collected from different places were treated with 40 mg L -1 Al 3+ screened in the pretest. There were significant differences between treatment and control groups in germination rate, germination energy, germination index, root length, bud length, root dry weight, bud dry weight, root-shoot ratio, and the genetic diversity index ranging from 1.43-2.03 and 1.51-2.06, respectively, showing extensive genetic variation. Cluster analysis was carried out based on A value, exhibiting that the tested cultivars were roughly divided into groups with three aluminum toxicity tolerance grades. The first group including two varieties is tolerant to aluminum toxicity, the second group including 19 varieties is sensitive to aluminum toxicity, and the last group containing 31 other varieties is very sensitive to aluminum toxicity. Combined with the optimal regression equation, seven indexes of pea seed germination rate, germination potential, germination index, bud length, root length, bud dry weight and root dry weight were used to comprehensively evaluate and identify the aluminum toxicity tolerance of pea during germination period. Through comprehensive evaluation and cluster analysis, germplasm C175 and C145 were screened out with strong tolerance to aluminum toxicity in germinating stage, which can be used as important resources for breeding near varieties and studying the mechanism of tolerance to aluminum toxicity in pea.

Co-sponsored:
the Crop Science Society of China
the Institute of Crop Science, CAAS
China Science Publishing & Media Ltd.
Published: Science Press
Editor-in-chief: Wan Jian-min
Associate Editors-in-Chief:
Chen Xiao-ya Yang Jian-chang Zhang Xian-long Wang Jian-kang Xu Ming-liang Liu Chun-ming Wang Dao-wen Sun Chuan-qing Ding Yan-feng Jin Wei-wei Chu Cheng-cai Cheng Wei-hong
Director of the editorial department:
Cheng Wei-hong
CN 11-1809/S
ISSN 0496-3490
Post subscription code: 82-336

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  • Started in 2013
  • Covered by SCIE
  • Open access in ScienceDirect

Editor in chief: Wan Jian-min
CN 10-1112/S
ISSN 2095-5421, 2214-5141(online)
Online published:
https://www.sciencedirect.com/journal/the-crop-journal
Submission: https://www.editorialmanager.com/cj/
E-mail: cropjournal@caas.cn
Tel: 8610-82108548

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