| Potato plant growth is affected by both biotic and abiotic stresses.Its yield and quality determine the main factors of the commercial value of the potato.This experiment explored the effects of Syngenta’s fungicide Amistar,seed coating agent Thiamethoxam,and Diquat dibromide on the physiological characteristics and tuber quality of potato under drought conditions.Qingshu No.9,Longshu No.6 and Atlantic with different drought resistance were used for testing.They were treated with Amistar Ditch(A),Thiamethoxam seed dressing(T)before planting and the sprayed Diquat dibromide(DQ)on stems and leaves at pre-harvest collection were treated with chemicals,the full irrigation was control(CK,θw: 60-70%),the drought treatment(D,θw: 30-40%),and drought with pesticide treatment(A-D,T-D,DQ-D).Through the determination of leaf photosynthetic index,different tissue antioxidant enzyme activities,Malondialdehyde(MDA)and proline content,as well as yield per plant and tuber quality indicators were used to evaluate the growth under drought conditions by Amistar and Thiamethoxam.The effects of Diquat dibromide on the storage performance of potato tubers were evaluated by measuring the thickness of potato skin,the activity of polyphenol oxidase and the quality index.In order to explore the potential functions of three different functional pesticides in potato production and storage,provide scientific basis and technical supported for the development of new pesticides,and provided decision-making basis for potato field planting management and efficient utilization.The main results of this study were as follows:(1)Amistar caused a significantly increase in photosynthetic rate and stomatal conductance of potato leaves.Under full irrigation conditions,it caused the activity of leaf catalase(CAT)and ascorbate peroxidase(APX)to be enhanced.It shows that Amistar has the effect of delaying plant senescence.Under drought conditions,the accumulation of MDA and proline content in leaves were reduced,and leaded to increased drought tolerance of plants.Amistar increased the yield per plant of Qingshu No.9,Longshu No.6 and Atlantic A than CK treatment by 30.74%,59.87% and 5.90% respectively,and increased the yield per plant of A-D than D by 15.17%,43.43% and 16.49% respectively.In addition,A treatment of Qingshu No.9,Longshu No.6 and Atlantic comprehensive quality scores were 1.184,2.856,0.621,A-D were-1.112,-0.240,-0.349 respectively,and Amistar had a higher degree of tuber quality improvement under drought conditions.(2)Thiamethoxam significantly increased the stem thick of potato plants,and can also increased the SPAD value of leaves indirectly.Under full irrigation and drought conditions,the activity of root CAT and APX can be reduced,and the accumulation of MDA and proline content can be reduced,increased resistance and reduced cell membrane lipid damage.In addition,Thiamethoxam significantly increased the yield per plant of Qingshu No.9,Longshu No.6 and Atlantic T than CK by 50.54%,114.86% and 14.71% respectively,and T-D increased significantly compared with D treatment 279.16%,29.77%,25.29%,T treatment of tuber quality scores were 1.775,1.341,1.476 respectively,T-D treatments were 0.149,-0.981,-0.405 respectively,and Thiamethoxam had the biggest improvement in tuber quality of Qingshu No.9.(3)Diquat dibromide caused a significant increase in the thickness of potato skin,and the thickness of potato skin was larger than that of full irrigation conditions under drought stress.Diquat dibromide made the PPO activity of potato tubers decreased under full irrigation and drought stress.Where DQ-D was compared to D treatment,Qingshu No.9,Longshu No.6 and Atlantic significantly decreased 7.95%,19.37%,36.24% respectively when stored for 60 days.In addition,When stored for 30 days,the comprehensive scores of treatment quality of Qingshu 9 and Longshu 6 were DQ>DQ-D>D>CK,and the comprehensive scores of Atlantic treatment quality were DQ-D(1.8993)>CK(1.2806)>DQ(1.2211)>D(0.4973). |
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