The Effects Of Sowing Date On Growth And Yield Of Short Season Cotton(CCIR50) In Different Cropping Patterns

The wheat-cotton double cropping system can improve crop yield per unit land area,and the cropping system was become more and more important portion in Yellow River Valley cotton region.It can provide strong technical support for achieving high-yielding and high-efficiency of crop production through studying the charactersistics of cotton growth,yield and quality and exploring new cultivation technology and mechanismof cotton-wheat double cropping system.Field trailwas conductedin 2015-2016 inthe farmof Cotton Research Institute of CAAS,Anyang,Henan(36°07’N,116°22’E).Theshort season cotton of CCRI 50 wasused in this study(an insect-resistant cotton with Bt gene).Four Different planting date treatments were arranged in both monoculture cotton and cotton-wheat double cropping systems.The agronomic traits,accumulation and partitioning of dry matter,and yield were measured and recorded.The spatiotemporal distribution of reproductive organswas alsostudied.The results were as follows:(1)The effects of sowingdateson spatiotemporal dynamics of cottonbollin different cotton croppingsystems.The cropping patternshad effects on the spatial distribution of cotton bolls.Due to the spatial heterogeneity within the cottoncanopy,the different spatial boll distributionwithin cotton plantwas one of the reasons for the variation of boll weight.The bolls in the wheat-cotton double cropping systemwere significantly fewerthan thatin the single croppingsystem.In the wheat-cotton cropping system,the planting date of May 25 resulted in the most bollswhich mainly distributedat the 1st to 8th fruitingbranches.In addition,the bollretention was reduced compared to that in the single croppingsystem.(2)The effects of planting dates on agronomic traits of short season cotton in different cotton cropping systems.The differencesin phenological period of CCIR50 under different sowing dates and planting patternswere mainly observed in seedling stage and the flowering and boll development stage,and there is no significantdifferencein squaring stage.In wheat and cotton cropping system,the boll number per plant and the total fruiting sites per plant are fewer than those in the monoculture cotton.The latest planting date resulted in drasticallydecreased peak leaf area index as a result of the shorten growth duration.The sowing date of May 25 produced the most branch numbers and fruiting sites.For the same sowing period,the accumulated rates of reproductive organsand dry matter of the CCIR50 in wheat-cotton cropping system were significantly lower than those in the monoculture cotton.Consequently,due to delayed growth,insufficient accumulation of dry matterandreduced allocation rate to the reproductive organs,the late-sown cotton had lower seed cotton yield.(3)The effects of swoing dates on yield ofshort season cotton in sowingdatesdifferent cotton cropping systemsThe yield of seed cotton was determined by the number of bolls per area and boll weight.The highest yield ofseed cotton was obtained in the sowing date of May 25 in single croppingsystem,in which the yield ofseed cotton reached3891.0 kg/hm~2,while in wheat-cotton system,The highest yield was2766.8 kg/hm~2,sowing on June 5,which is 8.4%higher than the sowing dateof June 15.This study indicated that the cotton cropping system and sowing dateaffected cotton yield components and subsequently affected seed cotton yield.