Effects Of Pruning Methods And Canopy Pattern On Temporal And Spatial Distribution Of Bolls And Ecophysiological Characteristics In Cotton

Pruning methods and canopy heights have been widely reported as a cultivation technology measure for unilateral application to cotton.However,there are few reports on comprehensive utilization of both.This study aims to integrate the pruning method and canopy height.Measures to create a good group canopy structure to achieve cotton production and efficiency.In the period of 2016-2017,Ganmian 958 was used as the test material,and split-zone design was adopted to study different pruning methods（vegetative branch removal and vegetative branch retention）and canopy height（high and low canopy,low canopy,and high canopy）in Baoding Qingyuan Experimental Station of Hebei Agricultural University.The impacts of cotton leaf area index,photosynthetic characteristics,microclimate in cotton fields,dry matter accumulation and distribution,cotton boll spatiotemporal distribution,yield and fiber quality were provided in order to provide theoretical and technical guidance for high-yield and high-quality cultivation of cotton in the Yellow River Basin.The main research results are as follows:1.In different canopy structures,the treatment of vegetative branch retention can significantly increase the leaf area index of cotton,Its maximum LAI can reach 4.55 and increase 13.18%compared to the treatment of vegetative branch removal,which significantly enhanced the cotton leaf photosynthetic potential and population photosynthetic rate;and high&low plant-alternated population can ensure a certain leaf area index,improve the group’s ventilation and light conditions,increase the cotton leaf photosynthetic potential and population photosynthetic rate,the photosynthetic potential relatively increased by 28.06%,and the photosynthetic rate of the population increased by22.9%than low canopy population.2.The treatment of vegetative branch retention could significantly increase the light interception in the middle of the canopy,increased 17.5%compared with the treatment of vegetative branch removal in boll opening stage,reaching a significant difference level.And the treatment of vegetative branch retention can significantly reduce air temperature inside the canopy of the cotton plant,increase the CO₂ concentration at the bottom of the cotton plant and the relative humidity in the air;The high&low plant-alternated populations compared to high canopy populations and short canopy populations not only help to increase the light interception in the upper canopy,but also significantly increase the CO₂ concentration in the population,lower the air temperature and relative humidity,maintain a good microenvironment in the cotton field,and reduce the rate of rotten boll and the rate of abscission boll,thus increase production.3.The dry matter accumulation dynamics of shoots with different canopy structures were in line with the growth curves simulated by the logistic equation.the treatment of vegetative branch retention can significantly higher than the treatment of vegetative branch removal with the maximum accumulation rate of dry matter and the maximum dry matter quality,but it will significantly reduce the proportion of dry matter allocated to the vegetative organs and reproductive organs on the main stem of the cotton plant,thereby affecting the development of the bolls on the main stem;And the proportion of the dry matter of the reproductive organs of the 5-8 fruit branches in the high&low plant-alternated population can significantly higher than the low canopy and high canopy population,increased significantly by 26.7%than low canopy population.4.Pruning methods and canopy height had significant effects on the temporal-spatial distribution of cotton bolls,On temporal distribution,retention of vegetative branch treatment can significantly increase the number of summer bolls,relatively increased 9.6%than remove of vegetative branch treatment;High and low plant-alternated canopy can significantly increase the number of pre-summer bolls,but the number of autumn bolls was less than the high canopy;On spatial distribution,the number of inside bolls much more than the periphery bolls;retention of vegetative branch treatment can decreased the boll number of fruit position,but the boll of stem more dispersed than remove of vegetative branch treatment;The boll of remove of vegetative branch treatment was concentrated on the lower part,but the boll of retention of vegetative branch treatment was on the middle part in different canopy structure.The effect of pruning methods and canopy pattern on the upper branch of cotton was significant,the number of upper branch bolls of high canopy of vegetative branch removal was the most.5.The pruning method had no significant effect on cotton seed cotton and lint yield,However,the yields of seed cotton and lint cotton of the high&low plant-alternated canopy were significantly higher than the high canopy and low canopy groups.In addition,the interaction effect of the pruning method and canopy pattern on cotton yield was significant.In different canopy structures,the highest yield of seed cotton was found in the high&low plant-alternated canopy of vegetative branch removal,up to 4640kg?hm-2;But it’s no significant difference with the high&low plant-alternated canopy of vegetative branch retention groups in lint yield.The pruning method and the height of the canopy had little effect on the fiber quality of bolls,and their performance was consistent for two years.