The Effect Of Drip Irrigation Amount On Chemical Topping And Yield Of Cotton Which Grown In Northern Xinjiang

?Objective?Manual topping is a vital technical in cotton cultivation for a long time,and it is also the only technology that can not be mechanized at present.It is of very important to explore the technology of replacing manual topping to realize the full mechanization of cotton.To normalize the wide spread application of the chemical topping,this paper have important implications on the regulation of the machine pick up cotton yield and quality by chemical topping.Combine the phenomenon of regrowth after chemical topping with the water management requirement in agricultural production,research the regulation of growth and development in cotton under different drip irrigation amount treatments and chemical topping,explore the optimum drip irrigation amount during spraying the chemical topping medicament.This study will provide arrangement methods for control the vegetative growth and facilitate the reproductive growth of boll in cotton.?Methods?Under the natural conditions,by setting the manual topping as control,use two kinds of chemical topping medicament(Flumetralin and DPC)and three drip irrigation amount treatments(high drip irrigation: 38m3/666.67m~2;middle drip irrigation: 32m3/666.67 m~2;low drip irrigation:27m3/666.67 m~2).Measured the difference in agronomic characters(plant height;Branch length;the ratio of fruit node/fruit branch),canopy structure(LAI,DIFN and LIR),defoliation rate,dry matter distribution and yield components.Analyze variation of plant type,canopy structure,dry matter distribution and yield of the chemical topping cottons under different drip irrigation amounts.?Results?(1)The results showed that there was a significant interaction effect between topping methods and drip irrigation amount on cotton plant height and branch length.Under the interaction of drip irrigation amount and topping type,there was significant difference of plant height and branches length after spraying the chemical topping medicament 7 days and 14 days respectively.Average plant height and branches length under middle drip irrigation were decreased by 6% and 12% respectively than those under high drip irrigation and were increased by 13% and 14% respectively than those under low drip irrigation in chemical topping cottons;There was no significant difference in chemical topping cottons yield between middle drip irrigation and high drip irrigation treatments,but chemical topping cottons yield was increased by 7%-8% under middle drip irrigation than that under low drip irrigation treatments.Defoliation rate and miscellaneous leaves amount had no significant difference between the chemical topping and manual topping,but low drip irrigation can increase defoliation rate in chemical topping cotton;Although the chemical topping significantly reduced the boll weight of upper branches,it had no significant effect on the final yield and lint percentage.(2)Chemical topping cottons have the high leaf area index(LAI)and the longest duration.under middle drip irrigation,increased the photosynthetic area.The appropriate DIFN,light distribution and canopy structure benefit to increased the light efficiency.The higher dry matter and improved the proportion percentage of photosynthetic material to reproductive organs.The lower drip irrigation amount can also decreased the cost compared with the high drip irrigation.?Conclusion?Therefore,the amount of two irrigation after chemical topping should be under the middle irrigation treatment.In this way can not only regulated the plant type and defoliation rate,but also can improved the canopy structure and light transmittance in chemical topping.It can also facilitate the allocation of photosynthetic materials to reproductive organs.Totally,the middle drip irrigation treatment after chemical topping can increased the yield and labor productivity,decreased the costs,which makes it preferable to applied.