Effect Of Mepiquat Chloride On Summer Direct Seeding Cotton

The application of mepiquat chloride?MC?is one of the conventional measures to increase yield in cotton production.But is it necessary to apply MC in the efficient cotton production pattern characterized by late sowing,high density and reducing fertilizer? To answer the question,we carried out this study.The experiment was conducted at the experimental farm of Huazhong Agricultural University in 2015-2016.Huamian 3109?Gossypium hirsutum L?was planted in the summer,high density?100 thousand plants per hectare?,once fertilizer?fertilizer to all see the flowers once fertilized?conditions,set up 5 MC dosage?g/hm₂??0,30,60,90,120?.To study different MC dosage on cotton growth,yield and yield components,fiber quality,plant morphology,squares?flowers and bolls distribution and physiological property,in order to explore the effect of applying MC on summer sowing cotton.The main results are shown as follows:1.Compared with non spraying treatment,spraying MC had the trend of extending the cotton boll period?increased by 2 3 d,except MC90 treatment?,but no difference in growth period,which was 113 d?MC120 117 d?.2.Compared with non spraying treatment,spraying MC not increased the boll weight significantly,but decreased the boll number per unit area,reduce the lint percentage.Therefore,the yield is reduced,and the larger the dosage,the greater the reduction.The cotton seed index and fiber quality decreased with the time of harvest.However,the application of MC could increased the seed index of each harvest time and improve the quality of cotton fiber,especially the cotton fiber of the third time.3.Application of MC significantly reduced the number of main stem nodes,green leaves and fallen leaves of cotton,but extended the leaf longevity;and it also reduced the plant height and the internote length of main stem,which were positively correlated with the amount of MC.In addition,spraying MC reduced cotton leaf area,especially fruit leaf area;the specific leaf weight increased.4.Cotton petiole length increased gradually with the bottom up node position,and reached the maximum length?about 16 cm?to the middle part of stem,then reduced.The distribution of petiole length was spindle-shaped.Spraying MC shortened the branch length and the first fruit node length,and the decrease range increases with the increase of MC dosage.As well the upper branches and fruit segment length decreased more than the lower branches.5.MC had little effect on nitrate nitrogen of cotton main stem function leaf petiole before fertilization.After fertilization,nitrate nitrogen content of MC30,MC60 and MC90 increased significantly,and increased with the increase of MC dosage.The increase in protein was after the increase in nitrate nitrogen,and treatments were consistent at earlier stage.MC30,MC60 and MC90 increased afer DAE73,but the variation is small.High amount of MC?MC120?inhibited the increase of soluble protein.MC increased the early stage,decreased the later stage of soluble sugar content of functional leaves of cotton,but it did not change the trend of variation.It can be seen that although spraying MC is a routine method of increasing production of cotton,it should be used carefully under the condition of summer direct seeding,high density,low fertilizer amount and single fertilization.