| Cotton is one of the most economically important crops in the world and is also the main raw material for the textile industry.Mechanized breeding has become an important direction for the development of cotton production in recent years.By combining mechanized picking with breeding technology,the production efficiency of cotton can be improved,and the labor cost of manual picking can be reduced.The selection and breeding of mechanized cotton varieties has been one of the most important links in cotton production in recent years.By choosing mechanized cotton varieties that are high-yielding,high-quality,and adaptable,the cotton production process can be made more efficient,resulting in reduced production costs and supporting the sustainable development of the cotton industry.To screen suitable germplasm resources for mechanized cotton and provide new materials for mechanized cotton breeding,this study conducted two years of field planting and management of 438 Gossypium hirsutum materials in Kuche City,Xinjiang.By measuring 27 traits related to agronomic,yield,quality,defoliant spraying,growth period,plant type,and mechanized harvesting through correlation analysis,differential analysis and cluster analysis,we have identified G.hirsutum materials that are well-suited for mechanized harvesting,and which possess desirable yield and quality traits.The main results are as follows:1.The descriptive statistical analysis of 27 traits of 438 G.hirsutum germplasm resources revealed that the materials in this study were mainly cylindrical and tower-shaped with a medium to open boll and a medium to long fiber length.The coefficient of variation for agronomic traits varied widely,ranging from5.92% to 31.04%.Among these,the initial fruit branch number,initial fruit branch height,plant height,fruit branch number,effective fruit branch number,and boll number per plant all exhibited coefficients of variation exceeding 10.00%.Meanwhile,the coefficient of variation for yield traits ranged from 10.72% to16.18%,the coefficient of variation of lint quality is 16.2%.These results suggest that breeders have prioritized the improvement of yield traits in the breeding process.With different days of defoliant treatment,the coefficient of variation of fruit branch leaf number increased gradually from 55.62% to87.20%,while that of lint boll number decreased gradually from 100.43% to 62.36%,and those of lint percentage and defoliation rate decreased gradually from 85.00% to 35.38% and from 52.50% to 17.33%,respectively.The coefficient of variation of total leaf number increased gradually from 57.48% to 89.18%,that of leaf branch leaf number increased gradually from 93.45% to 106.55%,and that of main stem leaf number increased gradually from 32.10% to 103.90%.These results suggest that different G.hirsutum materials have different sensitivities to defoliant,resulting in significant changes in the variation of defoliation-related trait indicators before and after spraying,as well as at different days after spraying,which provides reliable evidence for selecting materials that have fast defoliation rates and are sensitive to defoliant.2.According to the relevance analysis,increasing the number of effective branches on a cotton plant can lead to an increase in the number of bolls produced,resulting in a higher cotton yield and a shorter growth period for the cotton.An increase in boll weight can increase lint yield but decrease the seed cotton ratio.The number of bolls and lint yield are positively correlated with the total number of leaves,branches and leaves and negatively correlated with defoliation rate,hanging branch leaves,hanging branch rate and growth period.Lint yield is negatively correlated with leaf traits,hanging branch rate,and growth period.The defoliation rate is negatively correlated with leaf traits and positively correlated with the hanging branch rate.The total number of leaves is positively correlated with the number of main stem leaves,branch leaves,branch and hanging branch leaves and negatively correlated with the hanging branch rate.There is a positive correlation between the number of main stem leaves and the number of branches,as well as branch leaves,and the growth period.Similarly,the number of branch leaves is positively correlated with the number of branch and hanging branch leaves,but negatively correlated with the hanging branch rate.The numbers of branch and hanging branch leaves are positively correlated and negatively correlated with the hanging branch rate,respectively.The number of hanging branch leaves is positively correlated with the hanging branch rate and growth period.The hanging branch rate and growth period are positively correlated.After conducting a differential analysis,it was found that defoliant treatment resulted in a significant decrease in the total number of leaves,branch leaves,branch and hanging branch leaves,as well as main stem leaves.The minimum value for all of these factors was observed 20 days after treatment.The number of bolls,lint yield,and defoliation rate significantly increased,reaching a maximum value 20 days after treatment.3.This passage discusses a comprehensive clustering analysis of 438 G.hirsutum resources based on traits related to machine picking.The materials were divided into five clusters,with 84 materials in Cluster1,105 in Cluster 2,46 in Cluster 3,185 in Cluster 4,and 48 in Cluster 5.Upon analysis,it was found that there were notable differences in agronomic traits between the various clusters,while differences in yield traits were relatively minor,and there were no significant variations observed in quality traits.The average values of lint yield,lint percentage,and leaf number in Cluster 1 were significantly lower than those in the other clusters,while the average values of defoliation rate and growth period were significantly higher.Cluster 3 had the highest average values for lint yield and leaf number and the lowest average value for defoliation rate.Cluster 5 had the highest average value for lint percentage,and the average values of the growth period in the other four clusters were relatively close,except for Cluster 1.4.This paragraph talks about the selection of G.hirsutum resources with high yield and excellent quality based on machine-harvesting related traits.14 suitable cotton varieties were ultimately selected,including Ganmian 207,Gangzaomian 0379,Hangmian 12,Longzongmian 3,Quanmian 2005,Soviet Union 8909,Soviet research 608,Xinluzao 46,Xinluzao 48,Xinluzao 50,Xinluzhong 82-TH08-118,Xinluzhong 88-AW1041,Xinminmian 1,and Zhong JL16. |
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