Effects Of Drip Irrigation Frequency And Irrigation Amount On Potato Growth And Water Use Efficiency

Considering the lack of reasonable irrigation for the potato farmlands in sandy soil areas of Yulin,in northern Shaanxi Province,the effects of drip irrigation frequency and irrigation water amount on potato growth,yield,water use efficiency,quality,economic effect and water nutrient were systematically analyzed.It provides a theoretical basis for formulating a reasonable drip irrigation system in this area.The drip fertigation technology was used in the experiment to observe the plant height,leaf area index,dry matter accumulation,yield and composition,quality and maturity period nutrients indices of potato during the growing season,and calculate the water use efficiency and economic benefits,analyze the responses of these indexes to different irrigation frequencies and amounts.There were a total of nine treatments,including three irrigation frequencies,i.e.4d（D₁）,8 d（D₂）and 10 d（D₃）,and three irrigation amounts,i.e.60%ET_c（W₁）,80%ET_c（W₂）and 100%ET_c（W₃）,where ET_c is the crop water requirements.The following conclusions are obtained:（1）Drip irrigation frequency and irrigation water respectively for potato plant height,LAI and dry matter accumulation in mature measuring tool has a significant effect,the frequency of drip irrigation on yield and yield components has extremely significant effect,the interaction of potato plant height,LAI,maturation of amount of dry matter accumulation,yield and commodity potato were extremely significant effect.Under the same drip irrigation frequency,the plant height,LAI,dry matter accumulation,yield and yield composition significantly increased with the increase of irrigation water amount in each growth period.Under the same irrigation water,the irrigation water was at W1 and W₂levels respectively,and the frequency of drip irrigation increased.Plant height,LAI,dry matter accumulation,yield and yield components increased during each growth period.When fully irrigated,plant height,LAI,dry matter accumulation,yield and yield components first increased and then decreased with the decrease of drip irrigation frequency in each growth period.The maximum values of plant height,LAI,dry matter cumulative yield and yield components of potato during each growth period were obtained by D₂W₃ treatment.By linear fitting,it was found that plant height,LAI and dry matter accumulation of potatoes were significantly positively correlated with yield.（2）The frequency of drip irrigation,the amount of irrigation and their interaction have a very significant impact on the water use efficiency of potato irrigation,and the frequency of drip irrigation and their interaction have a very significant impact on the water use efficiency of potato.With the same frequency of drip irrigation,IWUE decreases gradually with the increase of irrigation amount.Under the same irrigation amount,the irrigation amount was W₁ and W₂ respectively,and the IWUE increased with the increase of irrigation frequency.When irrigation is sufficient,IWUE and WUE both increase first and then decrease with the increase of drip irrigation frequency.The difference between D₁W₂treatment with the highest WUE and D₂W₃ treatment with the highest yield was not significant,but the yield reduction was significant.（3）The frequency of drip irrigation had significant effect on the content of potato starch,vitamin C and reducing sugar.The interaction of the two had significant effect on potato starch content and extremely significant effect on vitamin C content.With the same frequency of drip irrigation,the content of tuber starch,vitamin C and economic benefit increased,while the content of reducing sugar decreased gradually.Under the same irrigation amount,the frequency of drip irrigation increased with W₁ and W₂ irrigation levels,the content of tuber starch,vitamin C and economic benefits increased,and the content of reducing sugar decreased.When fully irrigated,the frequency of drip irrigation was increased,the content of tuber starch,vitamin C and economic benefit first increased and then decreased,and the content of reducing sugar first decreased and then increased.Principal component analysis was used to analyze potato yield,water use efficiency,starch,vitamin C and reducing sugar.（4）Phosphorus,phosphorus and potassium accumulation were mainly concentrated in tubers at maturity stage.Nitrogen and phosphorus accumulation were expressed as follows:tuber>leaf>stem>root,and potassium accumulation was expressed as follows:tuber>stem>leaf>root.For the same treatment,the nutrient absorption efficiency was expressed as nitrogen>potassium>phosphate,and the nutrient utilization efficiency was expressed as phosphorus>nitrogen>potassium.With the same frequency of drip irrigation,the nutrient accumulation,absorption efficiency and utilization efficiency increased significantly with the increase of irrigation water.At the same irrigation volume,the frequency of drip irrigation increased at the W₁ and W₂ irrigation levels,and the nutrient accumulation,absorption efficiency and utilization efficiency increased gradually at the mature stage.At the level of W₃,with the increase of drip irrigation frequency,the nutrient accumulation,absorption efficiency and utilization efficiency at the mature stage first increased and then decreased,and the nutrient accumulation,absorption efficiency and utilization efficiency at the mature stage reached the maximum value in D₂ treatment and were significantly higher than those in D₁ and D₂ treatment.（5）Nitrate nitrogen,available phosphorus and available potassium in soil are mainly concentrated in the soil depth of 0⁴0cm,and the amount of available potassium remains is much higher than that of nitrate nitrogen and available phosphorus.In the same treatment,with the increase of soil depth,the residual amount of nitrate nitrogen gradually decreases,showing a change trend of"upper and lower",which has the characteristics of gathering in the shallow soil.At the same drip irrigation frequency and at the depth of 0⁴0cm,the nitrate nitrogen residue of W₃ treatment was significantly lower than that of W₁ and W₂treatment,the changes of available phosphorus residues in W3 treatment were significant,and those in W₁ and W₂ treatment were slow（except for D₃）,and the changes of available potassium residues in each treatment were significant.Within the soil depth of 40¹00 cm,the variation range of nitrate nitrogen,rapidly available phosphorus and rapidly available potassium residues gradually decreases.With the same irrigation amount,the nitrate nitrogen residue in the same soil layer increased with the increase of drip irrigation frequency.Within the depth of 0²0 cm,the residual amount of rapidly available phosphorus in soil increased with increasing frequency of drip irrigation.（6）In a comprehensive consideration,D₂W₃ treatment（drip irrigation frequency is 8 d,irrigation volume is 100%ETc）is a suitable irrigation system in sandy soil area of Yulin,northern Shaanxi.