[Objectives]To determine the optimal concentration of topping agents applied by unmanned aerial vehicles(UAVs)to effectively regulate cotton growth and improve production efficiency.[Methods]A field experiment was con...[Objectives]To determine the optimal concentration of topping agents applied by unmanned aerial vehicles(UAVs)to effectively regulate cotton growth and improve production efficiency.[Methods]A field experiment was conducted in Shihezi City,Xinjiang,employing a randomized block design.Five UAV-based chemical topping treatments were applied at dosages of 0.300,0.525,0.750,0.975,and 1.200 L/hm 2,designated as H1,H2,H3,H4,and H5,respectively.Additionally,manual topping(CK1)and tractor topping(CK2)treatments,both at a concentration of 0.750 L/hm 2,were included as control treatments.During the first 20 d following topping,parameters including primary agronomic traits of cotton(plant height,leaf age,number of fruit branches),dry matter accumulation and distribution,leaf area boll load(LAB),root-to-shoot ratio(RSR),leaf mass area(LMA),and leaf area index(LAI)were examined.At harvest,yield components,lint cotton yield,harvest index,and fiber quality were evaluated.[Results]Twenty days after topping,the concentration of the topping agent applied via UAV did not significantly affect cotton leaf age or the number of fruit branches.Additionally,no significant differences in plant height were observed among the five concentration treatments compared to CK2.However,plants treated with H1 exhibited significantly greater height compared to those treated with H5 and CK1,indicating that H1 was the least effective in controlling vegetative growth.Total dry matter accumulation(TDM),boll dry matter accumulation(BDM),LAB,and LMA all demonstrated an initial increase followed by a decrease as the spraying concentration increased.The highest TDM and reproductive organ dry matter ratio(RRDM)were observed in the H3 treatment.No significant differences were found among treatments for LMA,RSR,or LAI;however,LAB and single boll weight were greatest in the H3 treatment.Fiber quality parameters,including fiber length uniformity,micronaire(MIC),specific strength,and fiber maturity,initially increased and then decreased with increasing spraying concentration,whereas fiber elongation rate exhibited the opposite trend.The H3 treatment yielded the highest average fiber length uniformity and specific strength.[Conclusions]At optimal spraying concentrations,UAV-based application more effectively controls vegetative growth,promotes dry matter accumulation and distribution in cotton bolls,increases single boll weight,and enhances the MIC,specific strength,and fiber elongation rate of cotton fibers compared to manual and tractor spraying of topping agents.In summary,the use of UAVs for spraying chemical topping agents is recommended,with a suggested dosage range of 0.750 and 0.975 L/hm 2.展开更多
Background:Cotton production in China is challenged by high labor input including manual topping(MT).Recently,to replace MT in the Xinjiang cotton region of China,mepiquat chloride(MC)was applied once more than the tr...Background:Cotton production in China is challenged by high labor input including manual topping(MT).Recently,to replace MT in the Xinjiang cotton region of China,mepiquat chloride(MC)was applied once more than the traditional multiple-application;this was designated as chemical topping(CT),but it is unclear whether the amount of irrigation needs to be adjusted to accommodate CT.Results:The main plots were assigned to three drip irrigation amounts[300(I_(1))480(I_(2)), and 660(I_(3))mm],and the subplots were assigned to the CT treatments[450(MC)750(MC_(2)),and 1050(MC_(3))mL·hm^(-2)25%MC]with MT as a control that was performed after early bloom.The optimum drip irrigation amount for CT was explored based on leaf photosynthesis,chlorophyll fluorescence,biomass accumulation,and yield.There were significant influe nces of drip irrigation,topping treatme nts and their interaction on chlorophyll fluorescence characteristics,gas exchange parameters and biomass accumulation characteristics as well as yield.The combination of I_(2) and MC_(2)(I_(2)MC_(2))performed best.Compared with I_(2)MC_(2)the net photosynthetic rate(Pn),stomatai conductance(Gs),transpiration rate(Tr),and photochemical quenching coefficient(qP)of I_(2)MC_(2)significantly increased by 4.0%~7.2%,6.8%〜17.1%,5.2%~17.6%,and 4.8%~9.6%,respectively,from the peak flowering to boll opening stages.Moreover,I_(2)MC_(2) showed fast reproductive organ biomass accumulation and the highest seed cotton yield;the latter was 6.6%~12.8%higher than that of I_(2)MT.Further analysis revealed that a 25%MC emulsion in water(MCEW)application resulted in yield improvement by increasing Pn,φPSⅡ,and qP to promote biomass accumulation and transport to reproductive organs.Conclusion:The results showed that the 480 mm drip irrigation combined with 750 mL·hm^(-2)MC increased the rate of dry matter accumulation in reproductive organs by increasing Pn,φPSⅡ and qP to improve photosynthetic performance,thus achieving higher yield.展开更多
Plant growth regulators(PGRs)are frequently used to adjust cotton growth and development.The objectives of this study were to determine how PGRs affect plant morphology,light distribution and the spatial distribution ...Plant growth regulators(PGRs)are frequently used to adjust cotton growth and development.The objectives of this study were to determine how PGRs affect plant morphology,light distribution and the spatial distribution of leaves and bolls within the cotton canopy.The field experiments were carried out at Shihezi(Xinjiang Uyghur Autonomous Region,China)in 2014 and 2015.The experiment included two PGR treatments:(i)flumetralin(active ingredient(a.i),N-N-ethy)-2,6-dinitro-4-aniline and(i)mepiquat chloride(ai,1-dimethyl-piperidiniuchloride)plus flumetralin.No PGR(manual topping)was applied in the control treatment.The chemically-topped plants were taller and had more main stem internodes than the manually-topped plants.Furthermore,the PGRs significantly reduced the length of fruiting branches in the upper canopy,resulting in a more compact canopy.The maximum leaf area index was signifcantly greater in the chemically-topped treatments than that in the control.In particular,the PGRs increased leaf area index by 25%in the upper canopy.The leaf area duration was also longer in the chemically-topped treatments than in the control.Compared with the control,the chemically-topped treatments increased canopy diffuse non-interceptance by 35.75%in the upper canopy layer,while reducing the fraction of intercepted photosynthetically active radiation by 14.45%in the upper canopy layer.Light transmittance in the upper and middle canopy layers was greater in the chemically-topped treatments than in the control,which increased boll numbers in both the upper canopy and the middle canopy.However,the chemically-topped treatments resulted in less light-leakage through the lower canopy layer during the late growth stages,which had a tendency to increase boll numbers in the whole canopy.In summary,the PGRs optimized canopy shape,light distribution and the spatial distribution of bolls and leaves.展开更多
基金Supported by Xinjiang"Tianshan Talents"Program Project"Research and Demonstration of Key Technologies for Precise Monitoring and Pesticide Application by Unmanned Aerial Vehicle during the Cotton Topping Stage"(2023TSYCCX0126)Xinjiang Production and Construction Corps Science and Technology Innovation Project"Innovation Team Project for Intelligent Information Collection and Smart Management in Cotton Fields"(NCG202304).
文摘[Objectives]To determine the optimal concentration of topping agents applied by unmanned aerial vehicles(UAVs)to effectively regulate cotton growth and improve production efficiency.[Methods]A field experiment was conducted in Shihezi City,Xinjiang,employing a randomized block design.Five UAV-based chemical topping treatments were applied at dosages of 0.300,0.525,0.750,0.975,and 1.200 L/hm 2,designated as H1,H2,H3,H4,and H5,respectively.Additionally,manual topping(CK1)and tractor topping(CK2)treatments,both at a concentration of 0.750 L/hm 2,were included as control treatments.During the first 20 d following topping,parameters including primary agronomic traits of cotton(plant height,leaf age,number of fruit branches),dry matter accumulation and distribution,leaf area boll load(LAB),root-to-shoot ratio(RSR),leaf mass area(LMA),and leaf area index(LAI)were examined.At harvest,yield components,lint cotton yield,harvest index,and fiber quality were evaluated.[Results]Twenty days after topping,the concentration of the topping agent applied via UAV did not significantly affect cotton leaf age or the number of fruit branches.Additionally,no significant differences in plant height were observed among the five concentration treatments compared to CK2.However,plants treated with H1 exhibited significantly greater height compared to those treated with H5 and CK1,indicating that H1 was the least effective in controlling vegetative growth.Total dry matter accumulation(TDM),boll dry matter accumulation(BDM),LAB,and LMA all demonstrated an initial increase followed by a decrease as the spraying concentration increased.The highest TDM and reproductive organ dry matter ratio(RRDM)were observed in the H3 treatment.No significant differences were found among treatments for LMA,RSR,or LAI;however,LAB and single boll weight were greatest in the H3 treatment.Fiber quality parameters,including fiber length uniformity,micronaire(MIC),specific strength,and fiber maturity,initially increased and then decreased with increasing spraying concentration,whereas fiber elongation rate exhibited the opposite trend.The H3 treatment yielded the highest average fiber length uniformity and specific strength.[Conclusions]At optimal spraying concentrations,UAV-based application more effectively controls vegetative growth,promotes dry matter accumulation and distribution in cotton bolls,increases single boll weight,and enhances the MIC,specific strength,and fiber elongation rate of cotton fibers compared to manual and tractor spraying of topping agents.In summary,the use of UAVs for spraying chemical topping agents is recommended,with a suggested dosage range of 0.750 and 0.975 L/hm 2.
基金financially supported by the Research Fund for the National Natural Science Foundation of China (31760369)Xinjiang Corps Science and Technology Innovation Talent Program (2020CB014)Major projects of the eighth Division (2020ZD01)
文摘Background:Cotton production in China is challenged by high labor input including manual topping(MT).Recently,to replace MT in the Xinjiang cotton region of China,mepiquat chloride(MC)was applied once more than the traditional multiple-application;this was designated as chemical topping(CT),but it is unclear whether the amount of irrigation needs to be adjusted to accommodate CT.Results:The main plots were assigned to three drip irrigation amounts[300(I_(1))480(I_(2)), and 660(I_(3))mm],and the subplots were assigned to the CT treatments[450(MC)750(MC_(2)),and 1050(MC_(3))mL·hm^(-2)25%MC]with MT as a control that was performed after early bloom.The optimum drip irrigation amount for CT was explored based on leaf photosynthesis,chlorophyll fluorescence,biomass accumulation,and yield.There were significant influe nces of drip irrigation,topping treatme nts and their interaction on chlorophyll fluorescence characteristics,gas exchange parameters and biomass accumulation characteristics as well as yield.The combination of I_(2) and MC_(2)(I_(2)MC_(2))performed best.Compared with I_(2)MC_(2)the net photosynthetic rate(Pn),stomatai conductance(Gs),transpiration rate(Tr),and photochemical quenching coefficient(qP)of I_(2)MC_(2)significantly increased by 4.0%~7.2%,6.8%〜17.1%,5.2%~17.6%,and 4.8%~9.6%,respectively,from the peak flowering to boll opening stages.Moreover,I_(2)MC_(2) showed fast reproductive organ biomass accumulation and the highest seed cotton yield;the latter was 6.6%~12.8%higher than that of I_(2)MT.Further analysis revealed that a 25%MC emulsion in water(MCEW)application resulted in yield improvement by increasing Pn,φPSⅡ,and qP to promote biomass accumulation and transport to reproductive organs.Conclusion:The results showed that the 480 mm drip irrigation combined with 750 mL·hm^(-2)MC increased the rate of dry matter accumulation in reproductive organs by increasing Pn,φPSⅡ and qP to improve photosynthetic performance,thus achieving higher yield.
基金This study was financially supported by the 948 Program from Ministry of Agriculture of China(2016-X25)the National Key Technology R&D Program of China(2014BAD09B03)The authors are grateful to Dr.William J.Gale(Shihezi University,China)for his helpful revision of the paper especially in English language.
文摘Plant growth regulators(PGRs)are frequently used to adjust cotton growth and development.The objectives of this study were to determine how PGRs affect plant morphology,light distribution and the spatial distribution of leaves and bolls within the cotton canopy.The field experiments were carried out at Shihezi(Xinjiang Uyghur Autonomous Region,China)in 2014 and 2015.The experiment included two PGR treatments:(i)flumetralin(active ingredient(a.i),N-N-ethy)-2,6-dinitro-4-aniline and(i)mepiquat chloride(ai,1-dimethyl-piperidiniuchloride)plus flumetralin.No PGR(manual topping)was applied in the control treatment.The chemically-topped plants were taller and had more main stem internodes than the manually-topped plants.Furthermore,the PGRs significantly reduced the length of fruiting branches in the upper canopy,resulting in a more compact canopy.The maximum leaf area index was signifcantly greater in the chemically-topped treatments than that in the control.In particular,the PGRs increased leaf area index by 25%in the upper canopy.The leaf area duration was also longer in the chemically-topped treatments than in the control.Compared with the control,the chemically-topped treatments increased canopy diffuse non-interceptance by 35.75%in the upper canopy layer,while reducing the fraction of intercepted photosynthetically active radiation by 14.45%in the upper canopy layer.Light transmittance in the upper and middle canopy layers was greater in the chemically-topped treatments than in the control,which increased boll numbers in both the upper canopy and the middle canopy.However,the chemically-topped treatments resulted in less light-leakage through the lower canopy layer during the late growth stages,which had a tendency to increase boll numbers in the whole canopy.In summary,the PGRs optimized canopy shape,light distribution and the spatial distribution of bolls and leaves.
