Author:Ma Xiaomei1,Li Baocheng1,Dong Chengguang1,Zhou Xiaofeng1,Wang Xin1,Tian Qin1,Zhao Suqin2,Yuan Jiyong3*
Affiliations: 1. Key Laboratory of Cotton Biology and Genetic Breeding in the Northwest Inland Region of the Ministry of Agriculture and Rural Affairs/Cotton Research Institute of Xinjiang Academy of Agricultural and Reclamation Sciences; 2. Seed Industry Development Center of Xinjiang Uygur Autonomous Region; 3. Xinjiang Jinfengyuan Seed Industry Co., Ltd
Introduction:Ma Xiaomei, female, from Mianzhu, Sichuan, researcher, master, engaged in cotton genetics and breeding research. *Corresponding author, associate researcher, engaged in cotton breeding research.
Funds: National Natural Science Foundation of China "Functional and molecular mechanism of transcription factor GhZFP8 in cotton fiber development" (31960439); "Design and Cultivation of New Varieties of Stress-tolerant and High-yield Cotton" (2023ZD04040-5-2).
Source: Anhui Agricultural Sciences, Issue 8, 2024
Citation format: Ma Xiaomei, Li Baocheng, Dong Chengguang, et al. Comparative study on defoliation effect of early-maturing upland cotton Jinken 1402[J].Anhui Agricultural Sciences,2024,52(8):32-35,40.
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Leaves are the most important source organ of cotton, and more than 90% of the dry matter of cotton plants originates from leaves, and the vitality of cotton leaves is related to plant species and different leaf positions. Leaves are also the main component of the canopy of cotton populations, and optimizing the canopy structure is not only an important way to enhance the photosynthesis of crop populations, but also an important means and goal of crop variety improvement and cultivation technology. Therefore, it is of great significance to study the defoliation trajectories of different cotton varieties under the action of defoliants, and to find the relevant traits that play a significant role in the defoliation effect, which is of great significance for the targeted optimization of population canopy structure and variety advantage selection in the field. In recent years, the research on cotton defoliation has mainly focused on the exploration of defoliants, the exploration of the use of defoliants, and the screening of sensitive cotton varieties, and a lot of research has been done on the mechanism of cotton defoliation in the field of biotechnology. It was found that the effect of cotton defoliation was mainly affected by the following aspects: cotton variety sensitivity, cotton maturity, spraying method and spraying time, defoliation dose, and light, temperature and water that affected the efficacy of the drug. Jinken 1402 was selected and bred by the Cotton Research Institute of Xinjiang Academy of Agricultural and Reclamation Sciences through years of targeted selection of diseased areas, southern multiplication, resistance identification, quality testing, product ratio test, and multi-point test. In January 2019, it passed the approval and naming of varieties in Xinjiang Uygur Autonomous Region (No. 51 of 2018). This variety has strong boll formation, smooth and concentrated flocculent, moderate flocculent content, easy picking, and suitable for mechanical harvesting. In view of this, the author took the special climatic conditions of the early-maturing cotton area of Xinjiang as the background, and took the early-maturing upland cotton Jinken 1402 as the research object, and sprayed the deafoliation and ripening agent on this variety in 2020. After spitting, the indoor seed examination and quality analysis were carried out to explore the law of different types of leaves of this variety under the action of pesticides and the analysis of the ripening effect of cotton bolls, which provided an effective reference for the field planting and management of cotton planting households.
objective
In this paper, the morphological indexes of cotton leaves and the effect of defoliation and ripening of pesticides were studied for the early-maturing upland cotton variety Jinken 1402, which provided a theoretical basis for the early maturing machine-picked cotton varieties with excellent defoliation and ripening effect in production.
way
The defoliation rules and ripening effects of different types of leaves of Jinken 1402 were analyzed, and the important influencing factors affecting the leaf shedding rate of each plant under the action of defoliant were found.
outcome
◆Temperature change trend during defoliant spraying
The effect of defoliant depends on the metabolic activity of cells, which requires suitable temperature and humidity. If the temperature and humidity are too high or too low when spraying defoliant, it will affect the vitality of cotton leaves and affect the effect of defoliation. On September 5, 2020, the number of leaves before spraying defoliant was investigated, and on September 6, 2020, the minimum temperature was 13°C, the average temperature was 20.5°C, the average temperature was 23.1°C on the 1st day before spraying, the average temperature was 15.6°C on the 7th day after application, the average temperature was 15.6°C on the 14th day after application, and the average temperature was 12.2°C on the 21st day after application.
Fig. 1 Temperature trend in September 2020
◆Analysis of the effect of leaf shedding
Trends in leaf quantity of different types of varieties and leaves. Cotton leaves can be divided into three types: main stem and leaf, fruit branch and leaf, and leaf branch and leaf according to the different parts of the cotton leaf. It can be seen from Fig. 2, 3 and 4 that before spraying defoliant, there was little difference in the amount of main stem and leaf between the two varieties, but there was a significant difference in the amount of fruit branches and leaves, and the amount of fruit branches and leaves of Jinken 1402 was significantly higher than that of Xinluzao 61. At the same time, the defoliation trend of the main stems and leaves of the two varieties was relatively similar, and the amount of leaves of the main stems and leaves of the two varieties was similar after 21 days of application. From the perspective of the change trend of fruit branches and leaves, the amount of fruit branches and leaves per plant of Jinken 1402 was more than that of Xinlu Zao 61. The leaf shedding trend of the two types of Xinluzao 61 was relatively flat, and the change trend was similar. Under the premise that the leaf volume of the two types of leaves of Jinken 1402 was higher than that of Xinluzao 61, the leaf shedding effect of the two types of leaves was the same as that of Xinluzao 61 on the 21st day after the treatment, and the shedding characteristics of the branches and leaves of Jinken 1402 were particularly special, which was manifested as no obvious shedding before and during the application period, and a large amount of shedding began to fall off in the late stage of application, and the shedding effect was good. This indicates that the defoliation effect of varieties is not directly related to the leaf quantity of varieties. The susceptibility of fruit branches and leaves of Jinken 1402 to defoliants was that of Xinluzao 61.
Fig.2 Variation trend of main stem and leaf amount at different application days
Fig.3 Trends in the amount of fruits, branches, leaves and leaves at different application days
Fig.4 Variation trend of leaf amount in leaf branches and leaves with different application days
Variation trend of leaf defoliation rate of different varieties and types. In production, the defoliation rate of cotton machine needs to reach 90% during harvesting. In the three survey stages, the defoliation rate of main stems and leaves was 26.09%~91.30%, the defoliation rate of fruit branches and leaves was 25.0%~93.75%, and the defoliation rate of branches and leaves was 3.03%~90.91%. The defoliation rate of the main stem and leaves of Xinluzao 61 was 13.95%~81.40%, the defoliation rate of fruit branches and leaves was 6.12%~87.76%, and the defoliation rate of leaves and branches was 12.50%~87.50%. It can be seen that the defoliation rate per plant of Jinken 1402 is higher than that of Xinluzao 61, in which the fruit branch and leaf shedding rate reached 93.75%, and the main stem and leaf shedding rate and leaf branch shedding rate reached 90.00%. This indicated that Jinken 1402 was a cultivar sensitive to defoliants, and different types of leaves showed good defoliation effects, especially the leaf branches and leaves of this cultivar were higher than those of the control, but the defoliation effect was still better, indicating that the defoliation sensitivity of the cultivar was not affected by the leaf quantity per plant and canopy structure of the cultivar, but was related to the characteristics of the cultivar itself (Fig. 5).
Fig.5 Variation curves of defoliation rate of different types of leaves
Variation trend of leaf defoliation rate of different varieties and types. It can be seen from Fig. 6 that the defoliation rate of the main stems and leaves of the two varieties in the three time periods of the survey was 1.993%/d~3.726%/d (0~7d), 4.983%/d~6.832%/d (8~14d) and 2.484%/d~4.651%/d (15~21d), respectively. The defoliation velocity ranges of 0.875%/d~3.571%/d (0~7d), 5.248%/d~5.804%/d (8~14d) and 4.0185%/d~6.414%/d (15~21d), respectively. The range values of leaf shedding speed were 0.433%/d~1.786%/d (0~7d), 0.866%/d~5.357%/d (8~14d) and 5.357%/d~11.688%/d (15~21d), respectively. From the overall data range, it can be seen that the defoliation rate of the main stems and leaves of the two varieties was slightly faster than that of fruit branches and leaves at 0~7 days after treatment. On the 8~14th day after the treatment, the main stem and leaves of Jinken 1402 had the fastest defoliation rate, followed by fruit branches and leaves, and leaves and branches were the slowest. There was little difference in the defoliation rate of different types of leaves in Xinluzao 61, but the leaf detachment rate was the fastest, followed by fruit branches and leaves, and the main stem and leaf were the slowest. At 15~21 days after the treatment, the defoliation rate of the main stem and leaves of Jinken 1402 was the slowest, the fruit branches and leaves were slightly faster, and the leaves and branches were the fastest, reaching the peak. The fruit branches and leaves of Xinluzao 61 had the fastest defoliation rate, followed by the leaf branches and leaves, and the main stem and leaves had the slowest defoliation rate. It can be seen that in the early stage of drug treatment, the main stem and leaf of the two varieties shed the fastest, the fruit branch leaf defoliation was slightly slower, and the leaf branch leaf defoliation was the slowest. In the middle stage of treatment, the response of Jinken 1402 was more obvious, and the shedding rate of various types of leaves was more rapid than that at the initial stage, especially the shedding rate of main stem leaves and fruit branches was significantly higher than that of leaves, branches and leaves, and higher than that of Xinluzao 61 in the same period. In the late stage of treatment, the defoliation rate of the main stem and fruit branches of Jinken 1402 decreased, and the defoliation rate of leaves and branches reached the peak, and the defoliation rate of Xinluzao 61 was not significantly different, and the defoliation rate of Xinluzao 61 was not much different from that in the middle stage. It can be seen that the defoliation pattern of Jinken 1402 is based on the shedding law of "first removing the main stem and leaves, fruit branches and leaves, and then shedding the branches and leaves", while Xinluzao 61 is based on the whole application period, different types of leaves are shed, and the difference is not large.
Fig.6. Variation curves of defoliation speed of different types of leaves
◆ The change trend of the flocculation rate of each variety
Previous studies have shown that the correlation coefficient between the flocculation rate and defoliation rate of machine-harvested cotton gradually increases with the extension of defoliant spraying time, and reaches the maximum on the 15th day, indicating that the effect of machine-harvested cotton on plant defoliation and cotton boll flocculation reaches the maximum level on the 15th day after spraying defoliant.
It can be seen from Figure 7 that the number of flocculation boll per plant of Jinken 1402 was higher than that of Xinluzao 61 on the 21st day after the treatment, and the number of flocculent bells per plant of Jinken 1402 was also higher than that of Xinluzao 61. On the 14th day after treatment, the flocculation rate of Jinken 1402 reached 65.49%, which was also higher than that of Xinluzao 61, indicating that the defoliation sensitivity and post-drug flocculation rate of Jinken 1402 were better than those of Xinluzao 61.
Fig.7 Variation curves of leaf flocculation rate of two varieties
◆ Fiber quality before and after application
The defoliant application period of machine-picked cotton in the cotton area of northern Xinjiang is generally at the end of August and early September, and the time of spraying and the climatic conditions in the later stage of application will lead to changes in fiber quality. The results show that the specific strength of fiber is an important index to measure the quality of cotton fiber, and its formation process is closely related to the accumulation characteristics of cellulose.
From Table 1, it can be seen that the average length and length uniformity index of the upper half of Jinken 1402 fiber were significantly higher than those of Xinluzao 61, and the micronaire value index of Jinken 1402 was also better than that of Xinluzao 61, indicating that the fiber quality index of Jinken 1402 was better than that of Xinluzao 61 after spraying defoliant, and the index reached more than double three zeros, and the micronaire value index was excellent. At the same time, the changes in fiber quality of the same variety under pesticide application and non-application were observed, and it was found that the average length, breakage specific strength, length uniformity index, micronaire value and elongation at break of the upper half of the fiber of Jinken 1402 before pesticide application were better than those of cotton fiber harvested after application, indicating that the spraying of defoliant had a great effect on the fiber quality of Jinken 1402 in the year of the experiment. The quality indicators of Xinluzao 61 pesticide application and non-pesticide application also changed; This result is consistent with previous studies.
conclusion
According to the analysis of the defoliation effect of different types of leaves, it was concluded that the main stem leaves, fruit branches and leaves, and leaf branches and leaf contents of Jinken 1402 were higher than those of Xinluzao 61, but the defoliation speed and defoliation rate were higher than those of Xinluzao 61, and the defoliation effect was better than that of Xinluzao 61 at 21 days after treatment.
The analysis of flocculation and fiber quality of the two varieties showed that the number of flocculation bolls per plant of Jinken 1402 was higher than that of Xinluzao 61 on the 21st day after the treatment, and the flocculation rate per plant was higher, which was better than that of Xinluzao 61. The fiber quality index showed that the average length and specific strength of the upper half reached more than "double 31", which was better than that of Xinluzao 61.
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