15 May 2020, Volume 32 Issue 3
    

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    RESEARCH REPORTS
  • Lei Jiejie, Shao Panxia, Guo Chunping, Zhang Dawei, Tang Binghui, Nurimanguli Aini, Peng Yajuan, Cui Tianyu, Zhang Aoshen, Lin Hairong, Lin Zhongxu, You Chunyuan, Nie Xinhui
    Cotton Science. 2020, 32(3): 185-198. https://doi.org/10.11963/1002-7807.ljjnxh.20200509
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    [Objective] We completed anassociation analysis of economic traits for upland cotton using simple sequence repeat (SSR) markers. We then explored the allelic variation sites to analyze the genetic basis of economically important traits, studied the genetic mechanism of Xinjiang upland cotton, and aimed to accelerate efficient breeding of upland cotton. [Method] We carried out polymorphic scanning on 156 upland cotton varieties in Xinjiang by screening 73 pairs of SSR markers encompassing the whole cotton genome. We constructed boxplot maps using R statistical computing software and graphics language and used TASSEL software to correlate yield or fiber quality traits with significant allelic variation loci. [Results] We obtained 10 allelic variation loci related to yield traits using the correlation analysis of Xinjiang upland cotton varieties from six different environments. The interpretation rate of phenotypic variation ranged from 6.69% to 9.88% with an average of 8.43%. Twenty-three allelic variation loci associated with fiber quality traits and phenotypic variation interpretation rates ranged from 3.73% to 13.22% with an average of 7.52%. The 22 detected quantitative trait loci were reported in previous studies and 10 showed the same associated traits as previously reported. [Conclusion] The population genetic structure of Xinjiang upland cotton varieties is simple, the linkage disequilibrium level is low, and the phenotypic traits show a stable trend under six environments. Using association analysis, we discovered unique allelic variation genes related to yield and fiber quality and diverse allele loci.

  • Yang Yang,Xie Xiuqing,Su Honghua,Yang Yizhong
    Cotton Science. 2020, 32(3): 199-207. https://doi.org/10.11963/1002-7807.yyyyz.20200512
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    [Objective] Cotton has recently become one of the main hosts of Spodoptera exigua (Hübner), a moth species that damages the leaves of plants. With the widespread application and popularization of transgenic insect-resistant cotton, it is essential to understand the significance of leaf position on the population growth of S. exigua to effectively manage this pest. Leaf position was determined by the preference of this pest for the upper and middle leaves of cotton. [Method] To study the effects of different leaf positions on S. exigua population growth, we used three different kinds of transgenic cotton (transgenic cry1A cotton GK12, transgenic cry1Ac cotton Nu COTN 33B, and transgenic cry1A+CpTI cotton SGK321). We tested these three transgenic cotton varieties alongside their corresponding parental non-Bt transgenic cotton varieties (Simian 3, DP5415, and Shiyuan 321) as controls, respectively. We describe our results in the form of a population life table. [Result] (1) GK12 and SGK321 had an inhibitory effect on S. exigua, which exhibited some differences with the change of feeding position. The population trend index was substantially larger than 1. (2) Although there was an influence on the growth and reproduction of S. exigua after feeding on different leaf positions of the same transgenic cotton, the results show no apparent trend of change among leaf positions. (3) The population index of S. exigua that fed on Nu COTN 33B and SGK321 showed a lower tendency than that on conventional cotton varieties, but there was no significant difference between the population index for the S. exigua that fed on GK12 and Simian 3. [Conclusion] The population growth of the S. exigua that fed at different leaf positions on the three varieties of transgenic cotton increased throughout the experiment. This continuous population growth indicates that the transgenic cotton crops require additional management actions to control of the pest species, S. exigua.

  • Liu Guangya,Zhang Yanjun,Sun Xuezhen,Dong Hezhong
    Cotton Science. 2020, 32(3): 208-218. https://doi.org/10.11963/1002-7807.lgydhz.20200426
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    [Objective] Waterlogging adversely affects cotton growth and development, and continuous waterlogging may further result in considerable yield loss or crop failure. Enhancing the ability of cotton to adapt to waterlogging stress to preserve yield and quality is therefore critical. Ethylene is an important signal molecule, which plays a vital role in the process of plant stress resistance. However, the mechanism of ethylene in mitigating cotton waterlogging damage is still unclear. [Method] In this study, we setup an experiment with a cotton (Gossypium hirsutum L.) variety K638 in an electric rain shelter at the experimental station of the Shandong Cotton Research Center at Linqing, Shandong. We treated the cotton plants by waterlogging for 10 d during the flowering stage and used a non-waterlogged treatment as the control. During the waterlogging stress treatment, cotton plants were treated with an ethylene signal transduction inhibitor (1-MCP) or ethylene synthesis precursor (ACC) to detect the effects of ethylene content on cotton waterlogging injury and its physiological mechanism. [Result] The results revealed that a foliar spray of 1-MCP significantly inhibited ethylene synthesis in the stressed cotton plants, the content of ethylene and malondialdehyde (MDA) decreased by 5.3% and 39.2%, and the activities of alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC), and lactate dehydrogenase (LDH) decreased by 37.8%, 20.5%, and 8.2%, respectively. The photosynthetic rate, dry weight of the whole plant, and seed cotton yield increased by 13.5%, 3.3%, and 4.6%, respectively. The effect of ACC on the plants was the opposite because spraying ACC promoted ethylene accumulation in the waterlogged cotton. The ethylene and MDA content increased by 8.0% and 19.5%, respectively. The activities of ADH, PDC, and LDH increased by 17.5%, 11.2%, and 8.0%, respectively, while the photosynthetic rate, dry weight of the whole plant, and seed cotton yield decreased by 6.0%, 7.7%, and 8.0%, respectively. [Conclusion] In summary, reducing ethylene content in waterlogged cotton plants can significantly alleviate hypoxia damage caused by waterlogging stress and subsequently promote cotton growth and development by restoring physiological metabolism.

  • Xing Fangfang,Han Yingchun,Lei Yaping,Feng Lu,Wang Guoping,Yang Beifang,Wang Zhanbiao,Li Xiaofei,Xiong Shiwu,Fan Zhengyi,Du Wenli,Xin Minghua,Li Yabing
    Cotton Science. 2020, 32(3): 219-232. https://doi.org/10.11963/1002-7807.xfflyb.20200429
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    [Objective] Soil temperature affects the biochemical processes of crops; therefore, elucidating its spatial and temporal distribution characteristics in different cropping systems is an essential part of understanding how to boost cotton yield potential. [Method] In 2016 and 2017, continuous, real-time soil temperature monitoring was conducted at a depth of 10-110 cm in three cropping systems, including monoculture cotton (MC), wheat/intercropped cotton (WIC), and wheat/direct-seeded cotton (WDC). We investigated the growth process and various agronomic traits. [Result] Different cotton soil temperatures were found between MC and doubled in late May, indicating about 1-3 ℃ higher in the former during the symbiotic period. In early July, the cotton soil temperature of the double-cropping systems at 10-40 cm was higher than that of the MC, but showed the opposite at 40-110 cm. In early August, the differences in soil temperature reduced among the three cropping systems, while the soil temperature of the MC was still slightly lower than that of the double-cropping systems. After mid-September, the soil temperature of the double-cropping systems was lower than that of the MC. The soil temperature mainly influenced the duration of cotton seedling to squaring, and flowering to the boll-opening period. At the same time, there was a subtle effect on the squaring to flowering and boll period. In general, higher average soil temperatures were associated with shorter growth period durations. During the same period, the lowest daily soil temperature of the double-cropping systems occurred about one hour earlier than in the MC; however, the highest daily temperature appeared at the same time. There was a linear relationship between accumulated soil temperature and biomass at different layers across cropping systems. [Conclusion] Controlling the timing and quantity of irrigation water can assist agronomic practices by alleviating the effect of soil temperature on cotton growth. Increased accumulative soil temperature is beneficial to cotton emergence and boll opening in double-cropping systems. This study provides a theoretical basis for rational allocation and management of different cropping systems.

  • Xu Suixi,Wang Xuwen,Tian Qin,Kong Xianhui,Liu Li,Si Aijun,Wang Juan,Yu Yu
    Cotton Science. 2020, 32(3): 233-246. https://doi.org/10.11963/1002-7807.xsxyy.20200507
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    [Objective] We explored the genetic diversity of early maturity upland cotton germplasm resources in Xinjiang, China. We discovered specific germplasm resources and elite allelic variation related to fiber quality. [Method] We used 219 early maturity upland cotton accessions in our experiments and investigated 15 agronomic traits in three environments. We used a total of 128 pairs of simple sequence repeat (SSR) primers to scan for polymorphism. We then used NTsys-pc2.1 software to analyze genetic diversity, and Structure2.3.1 and Tassle5.0 software to perform association analysis of fiber quality traits based on phenotypic effect values to identify elite allele variation and conventional materials. [Result] A total of 244 loci were amplified by 128 marker pairs in 219 samples with an average of 1.91 loci per marker. The polymorphic information content ranged from 0.13 to 0.86 with an average of 0.63. The distribution range of the genetic similarity coefficient between materials in this population was 0.42-0.99 with an average of 0.61. The genetic similarity coefficient was between 0.5 and 0.7 and accounted for 90.19%. Through association analysis, we detected 11 markers that were significantly (P<0.01) associated with fiber quality traits, and discovered seven typical materials with specific allele. [Conclusion] In total, 219 Xinjiang early-maturing upland cotton germplasm resources have low genetic diversity. Based on SSR association analysis, we discovered some specific allele variations and conventional materials related to fiber quality traits.

  • CHEMCAL CONTROL
  • Song Xinghu,Xu Dongyong,Sun Lu,Zhao Wenchao,Cao Longlong,Zhang Xiang,Tang Jiyuan,Han Huanyong,Wang Hongzhe,Chen Hongzhang,Wang Lin,Zhao Bingmei,Du Mingwei,Tian Xiaoli,Li Zhaohu
    Cotton Science. 2020, 32(3): 247-257. https://doi.org/10.11963/1002-7807.sxhlzh.20200512
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    [Objective] Defoliation and ripening (D&R) is a prerequisite for the mechanical harvesting of cotton. The combination of applying thidiazuron (TDZ) and ethylene (ETH) to plants is the primary method for cotton D&R in China. The ecological conditions and planting patterns for cotton are quite variable across planting zones, so it is necessary to study the appropriate doses and ratio of TDZ and ETH for specific cotton planting areas. [Method] We conducted field experiments in 2018 at nine sites in Hejian and Handan, Hebei Province; Dezhou and Wudi in the Yellow River Valley, Shandong Province; Dafeng in the Yangtze River Valley, Jiangsu Province; and Shihezi Ⅰ, Shihezi Ⅱ, Luntai, and Shaya, Xinjiang. We used a TDZ (50% wettable powder) and ETH (40% aqueous solution) mixture at three concentrations, 450 g + 1 725 mL (T1), 600 g + 3 000 mL (T2), and 600 g + 4 500 mL (T3) per hectare, respectively, and the active ingredient ratios of TDZ and ETH were 1:3, 1:4, and 1:6, using water as the control. [Result] In Dafeng, the defoliation rate of the control was more than 80% at 16 days after spraying (DAS) and there was no significance observed in any of the treatments. The defoliation rate was significantly higher than the control at the rest of the sites at 14 DAS, and lower natural defoliation rates were associated with higher scopes. The defoliation rates were not consistent across the treatments, and in most cases, they were not significant. Some treatments reached 90% defoliation at 14-16 DAS. The boll opening rate (BOR) before spraying did not produce a significant increase compared with the control at 14-16 DAS. Lower BOR before spraying (such as at Shihezi I) was associated with a more substantial increase. Without spraying, a smaller increase was observed. There was no significant difference between the treatments and control after spraying at most of the experiment sites. Using the TDZ and ETH mixture did not have a significant effect on yield and yield quality in most experiment sites. [Conclusion] The defoliation rate increased significantly after 14 DAS, but there was little effect on the BOR, cotton yield, and fiber quality. Because of the stability of the D&R impact and cost, we recommend T2 for cotton D&R in each area of China.

  • RESEARCH NOTES
  • Zeng Yu,Yan Lei,Liu Yalin,Zeng Zijun,Jiang Cuncang
    Cotton Science. 2020, 32(3): 258-268. https://doi.org/10.11963/1002-7807.zyjcc.20200509
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    [Objective] This study investigates the effects of exogenous proline on the growth, physiological responses, and proline metabolism of cotton (Ekang No.8) seedlings treated with varying boron (B) concentrations. [Method] We conducted a randomized experiment with six treatments using the hydroponic method in a greenhouse at Huazhong Agricultural University. We applied three different concentrations of boron, including 0.02 μmol·L-1 (low-concentration B), 2.5 μmol·L -1 (medium-concentration B), and 100 μmol·L -1 (sufficient-concentration B). The first two are boron-deficient treatments. We also applied an exogenous proline treatment at 20 μmol·L -1(0 μmol·L -1 as control). When any significant difference among the treatments were observed, the related indicator was measured. [Result] The results showed that exogenous proline inhibited the growth of cotton seedlings under sufficient-concentration B treatment while promoting the absorption of B by roots under low-concentration B treatment. The application of exogenous proline to the seedlings under low-concentration B treatment reduced the contents of proline and H2O2 in leaves but increased the accumulation of MDA and H2O2 in roots. The activities of SOD and antioxidant enzymes (APX) in the roots and leaves were dramatically enhanced. Conversely, POD activity reduced significantly and there was no significant change in CAT activity relative to low-concentration B treatment. More importantly, we found that the application of exogenous proline under B deficiency increased the activities of P5CS, P5CR, OAT (synthetase), and PRODH (degrading enzyme) in proline metabolic pathways. [Conclusion] Applying exogenous proline under sufficient-B concentration inhibits growth. The application of proline to seedlings under low-B concentration promotes the absorption of B by roots, increases the activity of APX, and decreases the membrane lipid peroxidation in leaves. A B deficiency leads to proline accumulation in plants. The addition of proline under low-B concentration can reduce the proline content in leaves, which is caused by affecting the critical synthetase and catabolic enzyme activities in the proline metabolism pathway (Glu and Orn pathway). The main reason for this occurrence is the significant increase of proline dehydrogenase (PRODH) activity.

  • REVIEW & INTERPRETATION
  • Chen Huanxuan,Han Yingchun,Feng Lu,Yang Beifang,Lei Yaping,Wang Zhanbiao,Li Yabing
    Cotton Science. 2020, 32(3): 269-278. https://doi.org/10.11963/1002-7807.chxlyb.20200504
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    [Objective]Many facets of society continuously advance at a rapid pace, and agriculture plays a vital role as a pillar industry of the national economy. Cotton is an essential economic crop that is primarily cultivated in a traditional way. As the demands of society change, this conventional farming practice is no longer the most practical. In the future, smart agriculture will guide farming methods for cotton. In this paper, we provide a brief introduction to smart agriculture and summarize its various applications in cotton production and management. We listed and analyzed the practical use of smart agriculture in all aspects of cotton production and management. We further analyzed the advantages and disadvantages and provided the summary and prospect of smart agriculture as applied to cotton production management.