Fiber Development Characteristics And Temperature Response Of Upland Cotton Varieties With Different Maturity

【Objective】Xinjiang is the largest production base of high-quality commodity cotton in China,but with the widespread use of leaf-removing and ripening agents in large areas of machine-harvested cotton in recent years,the quality of cotton fiber in the cotton area has been seriously reduced,which directly affects the quality control of cotton fiber processing in xinjiang.As an important external environmental factor,temperature,together with genetic factors,is considered to be the main influencing factor for fiber growth and quality formation.In this paper,early-maturing upland cotton varieties were used as test materials,and medium-early-maturing varieties were selected as control,the method of sowing by stages was adopted to make boll development in different boll stage temperatures,to research the influence of temperature change on fiber accumulation and quality formation,to discuss the temperature index of effective flowering and bolling,to provide theoretical basis for improving the quality of machine-picked cotton fiber and promoting the production of high-quality cotton.【Methods】In this paper,four planting dates were set with the field planting date as the control.Mark different branches on the day of flowering,the material accumulation characteristics of fiber and cottonseed at different temperatures and the important enzyme activity indexes that affect the formation of fiber quality were measured by sampling in boll stage,the formation of main fiber quality,boll weight and final quality were investigated by sampling in boll development.The changes of dry matter accumulation,important enzyme activity and quality of cotton fiber of different types were analyzed based on the changes of temperature factor in boll stage,to clarify the relationship between temperature factor and fiber material accumulation,change of main enzyme activity and quality formation,summarize the influence of temperature on fiber development and the adaptability of varieties to temperature.【Results】The results of this experiment show that:(1)the rapid accumulation period of fiber dry matter in the upper branch of early maturing cultivars was from 18 d to 40 d at boll age under the temperature conditions of 23.8℃ average daily temperature(MDT)and 456.8℃ effective accumulated temperature ≥15℃ within 50 d after anthesis,the peak value of cottonseed weight/fiber weight appeared between 15-22 days of boll age,and the decrease of average daily temperature aggravated the allpacity of cottonseed and fiber.(2)The boll temperature drop formed in late sowing had a great influence on the formation of cotton fiber length in the middle fruit branch,and on the fiber strength and maturity of the upper fruit branch.Flower within 50 d MDT reduced to 20.8 ℃,the effective accumulated temperature of 15 ℃ to 305.1 ℃ or higher will seriously affect the fibre maturity,extend early maturity varieties of cotton fiber elongation stage,the impact is not big but in the end of fiber length,the sensitivity of fiber quality formation among varieties to boll temperature was shown as follows: xinluzao 59 > xinluzao 64 > xinluzhong 82.Xinluzhong 82 fiber growth and development and quality formation in low temperature during the blooming period(MDT 23.0 ℃ or less)are better,under the condition of good precocity.There were significant interaction effects between sowing date and variety on fiber specific strength.(3)The upper branch of xinluzhong no.82 showed a strong response to low temperature stress and strong cold resistance when MDT decreased to 20.8℃ within 50 days after flowering;at the fiber development stage,the average daily temperature ≤20.35℃ will lead to the toxic effect of reactive oxygen species on cotton fiber,resulting in decreased physiological activity;the peak activity of POD and SS in fiber was delayed and decreased with the decrease of MDT in boll stage.【Conclusion】In boll stage,MDT decreased the allometric growth degree between cottonseed and fiber,and the average daily temperature difference,to some extent,determined the length of rapid accumulation period of single fiber substance in the process of fiber substance accumulation.Sowing date and variety of the fibers form a significant interaction effect than strength,when the flowers within 50 d MDT reduced to 20.8 ℃,the effective accumulated temperature of 15 ℃ to 305.1 ℃ or higher will seriously affect the fibre maturity,at the same time,early maturing cotton fiber lengthened for a long time,but had little effect on the final fiber length.The average daily temperature ≤20.35℃ in the fiber development stage would lead to toxic effects of reactive oxygen species in cotton fiber,and the peak activity of POD and SS in fiber showed an obvious trend of delaying and decreasing with the decline of MDT in boll stage.Research found that xinluzhong 82 have good precocity sex and cold resistance at low temperature(MDT 23.0 ℃ or less)during the boll period,suitable for early cotton planting in northern xinjiang.