| This study,combined with the cotton spraying technology,focuses on the pesticide deposition rate for utilization of plant protection equipments in the whole growth period of cotton,the effect of pesticide spraying and the use order optimization based on the projected leaf area index(ratio of projected leaf area per unit area of land to total leaf area of the whole plant).This thesis analyzes the problems in the use of pesticides in cotton plant protection operation,and provides theoretical basis for the rational use of plant protection equipment in cotton production.Specific conclusions are as follows:1)The effects of pesticide spraying on cotton by T30 UAV and spray bar spray were evaluated.The spraying of 46% fluridine·acetamiprid WG 150 g/ha(dosage of preparation)to all plant protection equipments has good control effect on aphids in squaring stage,and the control effect is more than 82.4% 7days after pesticide spraying.The control effect of boom sprayer is relatively better than that of UAV.The control effect of 25% thiamethoxam WG 225 g/ha on thrips at flowering and bolling stage in UAV was relatively better than that of boom sprayer,and the control effect was 83.3% 3 days after pesticide spraying.After applying 250 g/L mepiquat chloride AS 750 m L/ha for 40 days,the inhibition rate of plant height of UAV was 26.41%,which was higher than that of boom sprayer(23.69%).Similar results were found in the fruit branch length,the internode length and the petiole internode ratio.The chemical topping effect of UAV was better than that of boom sprayer.After applying 540 g/L thiobenzene·diuron SC 180 m L/ha twice,the defoliation rate of UAV was better than that of boom sprayer,and it was 96.8% after 15 days of pesticide spraying.The boll opening rate of each plant protection equipments was above 95.0% after 15 days of pesticide spraying.2)Using Allure Red as the indicator,the measured value of pesticide utilization rate in the field was determined,and the number of spray methods,types of pesticide preparations and use of adjuvants were investigated by questionnaire.The methods of spray in cotton field are mainly divided into two methods:boom spray method,aviation spray method.The pesticide utilization rate of the two spray methods in different growth periods was higher than that of the boom spray except for the fifth measurement in squaring stage,and the average pesticide utilization rate was 41.3% and 34.3% respectively.The weights of aviation spray method and boom spray method were 0.4116 and 0.5884,respectively,and the synergistic coefficient of pesticide formulation was 1.09.The pesticide deposition for utilization with spray technology in the cotton field was 40.6% in Northern Xinjiang.3)The UAV fan-shaped nozzle(SX11001VS)and conical nozzle(TX-VK4)were selected,and the boom sprayer was used for drag nozzle spray mode and suspended nozzle spray mode.The projected leaf area index at different times of squaring stage was measured.Combined with the deposition characteristics of pesticide droplets in different canopy layers,the replacement period of plant protection equipment was analyzed.The projected leaf area index was 0.239,0.302,0.279 and 0.287 for four consecutive measurements,and the projected leaf area index had a downward trend when the bud stage was 10 days(0.279).The average coverage and average droplet density of cotton canopy UAV at 0 and 5 days of squaring stage were lower than those of boom sprayer,but they had higher effective spray coverage ratio,effective droplet density ratio and deposition amount.The density and coverage of droplets in the upper and middle canopy of UAV conical nozzle are relatively better than that of fan-shaped nozzle,but the droplet size and deposition amount are lower than that of fan-shaped nozzle.At 10 days of squaring stage,in the middle canopy,the average coverage,average droplet density,vertical penetration coefficient and deposition amount of UAV conical nozzle,fan-shaped nozzle and suspended nozzle spray mode are lower than that of drag nozzle spray mode.Based on the above results,the use period of plant protection equipment is recommended.Seedling stage: It is recommended to use UAV for spraying.Squaring stage: Both UAV and boom sprayer suspended nozzle spray mode can be used in 0-10 days.After 10 days,it should be replaced with the boom sprayer drag nozzle spray mode.It is recommended to use the drag nozzle spray mode for aphids control,and it is recommended to use the UAV for chemical topping.Flowering and bolling stage: It is recommended to use UAV for pesticide spraying,and UAV is recommended for control of thrips.Boll opening stage: It is recommended to use UAV for pesticide spraying,and the defoliant agent is recommended to be sprayed twice by UAV. |
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