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Cotton Science ›› 2020, Vol. 32 ›› Issue (5): 425-437.doi: 10.11963/1002-7807.qhklzh.20200729

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Cotton Chemical Topping by Applying DPC in Different Cotton-Growing Regions 

Qi Haikun1, Wang Sai1, Xu Dongyong2, Lu Zhengying3, Zhao Wenchao4, Hao Yanjie5, Zhang Xiang6, Li Wei7, Han Huanyong8, Wang Jiangtao9, Wang Hongzhe2, Chen Hongzhang10, Wang Lin11, Du Mingwei1, Tian Xiaoli1, Li Zhaohu1   

  1. 1. Crop Chemical Control Research Center, College of Agricultural , China University/ Engineering Research Center of Plant Growth Regulator, Ministry of Education, Beijing 100193, China; 2. Research Center for Cotton Seed Engineering Technology, Hejian, Hebei 062450, China; 3. Handan Academy of Agricultural SciencesHandan, Hebei 056001,China; 4. Dezhou Academy of Agricultural Sciences, Dezhou, Shandong 253000, China; 5. Binzhou Agricultural Machinery Research InstituteBinzhou, Shandong 256600, China; 6. Agricultural College of Yangzhou University, Yangzhou, Jiangsu 225001, China; 7. Huanggang Academy of Agricultural Sciences, Huanggang, Hubei 438000, China; 8. Cotton Institute Ground, Xinjiang Academy Agricultural and Reclamation Science, Shihezi, Xinjiang 832000, China; 9. College of Agronomy, Shihezi University, Shihezi, Xinjiang 832003, China; 10. Xinjiang Trustworthy Seed Industry Science and Technology Company of Limited Liability, Shaya, Xinjiang 842200, China; 11. Agricultural Technology Extension Station, Xinjiang Production and Construction Crops, Urumchi, Urumqi, Xinjiang 830001, China
  • Received:2019-08-14 Online:2020-09-15 Published:2020-10-09

Abstract: [Objective] The objective of this study was to investigate the stability and universality of cotton chemical topping by applying mepiquat chloride (1,1-dimethyl-piperidinium chloride, DPC) in different cotton-growing regions. [Method] Field experiments were conducted in 2018 at 10 locations in the Yellow River basin (Hejian and Handan, Hebei province; Dezhou and Wudi, Shandong province), the Yangtze River basin (Dafeng, Jiangsu province; Huanggang, Hubei province), and Xinjiang area (Shihezi location I and loacation II, northern Xinjiang and Luntai and Shaya, southern Xinjiang). Local cultivars/lines were used, and the experiments were performed using a randomized complete block design with three or four replicates. Accompanied with typical DPC multi-application in each location, chemical topping was conducted at 10 days before manual topping (T1) or at the same time with manual topping (T2) by applying four dosages of DPC (0, 90, 180, 270 g·hm-2), manual topping was used as the first control and non-topping as the second control. [Result] The time of chemical topping significantly affected cotton plant height (except for the results in Handan, Dezhou and Wudi) and the number of fruit branches (except for the results in Dafeng and Huanggang). It was observed that earlier chemical topping would result in lower cotton plant height and a fewer fruit branches. In Hejian and Shihezi location I, the average plant height across DPC chemical topping at T1 stage was not only lower than that of T2 stage but also 3.3 cm and 4.6 cm lower than that of manual topping, respectively. In most locations, chemical topping at T1 stage increased around two fruit branches per plant compared with manual topping, while in T2 stage the increased fruit branches per plant ranged from 2.3 to 7.7. Also, we found that a higher dosage of DPC resulted in shorter plant height (except for that in Huanggang). In some locations, plant heights of chemical topping with 180 g·hm-2 or 270 g·hm-2 DPC were even shorter than that of manual topping. The number of fruit branches per plant of 0 g·hm-2 DPC increased by 2.4-8.3 compared with manual topping. However, chemical topping with 90-270 g·hm-2 DPC significantly reduced the number of fruit branches compared with 0 g·hm-2 DPC. There were no significant differences in the number of fruit branches among three DPC dosages (90, 180, and 270 g·hm-2). In Handan, seed cotton yield of chemical topping at T2 stage was significantly lower than that of manual topping due to the decreased boll number, which is possibly associated with the high temperature and drought weather after chemical topping. While at other locations, most treatments of chemical topping by using DPC did not produce significant effects on yield. In addition, chemical topping by using DPC did not delay cotton maturity, characterized by their similar boll-opening rate and the first harvest rate to those of manual topping before spraying harvest aids. [Conclusion] Cotton chemical topping with DPC is more stable and universal across different cotton-growing regions. We suggest that 90-180 g·hm-2 DPC could be used at the same time with manual topping for cotton chemical topping.

Key words: cotton, DPC, chemical topping, plant height, number of fruiting branches, yield, maturity