Effects And Comprehensive Evaluation Of Different Water And Fertilizer Supplies On Growth,Yield And Quality Of Greenhouse Cucumber

Water and fertilizer were overused in agriculture,which has caused serious waste of resources and environmental pollution,and also restricted the sustainable development of agriculture in China.How to allocate water and fertilizer resources reasonably is one of the important research topics now.Using cucumber as material,orthogonal test method was adopted under the condition of water and fertilizer integration to study the effects of different irrigation water limits（W₁:65%θ_F;W₂:75%θ_F;W₃:85%θ_F）,nitrogen(N₁:252kg·hm^-2;N₂:360kg·hm^-2;N₃:468 kg·hm^-2)and potassium(K₁:378 kg·hm^-2;K₂:540 kg·hm^-2;K₃:702 kg·hm^-2)fertilizer on the growth,physiology,yield and fresh fruit quality of greenhouse cucumber,so as to provide scientific water and fertilizer management methods for greenhouse cucumber cultivation in Northeast China.The main results were as follows:（1）Plant was mainly affected by limit of water control and nitrogen fertilizer application.The plant height increased with the increase of irrigation water limit,and with the increase of nitrogen application rate,the plant height increased first and then decreased.Average plant height of W₃was 11.24%and 5.94%higher than that of W₁and W₂,respectively.N₂and N₃were 9.64%and 8.36%higher than that of N₁and N₃,respectively,and the difference was significant.Stem diameter increased with the increase of limit of water control,and increased first and then decreased with the increase of nitrogen application rate.The average stem diameter of N₂was 10.73%and 3.57%higher than that of N₁and N₃,respectively.Total fresh weight and dry weight of plants were significantly affected by the limit of water control and nitrogen application rate.Increasing the irrigation water limit and nitrogen application rate could significantly increase the total fresh weight and dry weight of plants.（2）In the initial fruit stage,Net photosynthetic rate of cucumber increased with the increase of limit of water control and fertilizer application.The average net photosynthetic rate of W₃irrigation treatment was 15.48%and 9.01%higher than that of W₁and W₂,respectively.The net photosynthetic rates of N₂and N₃treatments were 6.63%and 10.69%higher than that of N₁,respectively.The net photosynthetic rates of K₂and K₃treatments were8.71%and 10.69%higher than that of K₁,respectively.The net photosynthetic rate in full bearing period increased with the increase of limit of water control.With the increase of fertilizer application,the net photosynthetic rate increased first and then decreased.At the late fruit bearing stage,only limit of water control had a significant effect on net photosynthetic rate.The transpiration rate of different irrigation treatments was W₃>W₂>W₁.The content of chlorophyll in different fruit-producing stages was the highest under W₂water control and N₂application,and increased with the increase of potassium application in the initial fruit stage.The effect of potassium application on chlorophyll content was not significant in the full bearing period and the late fruit bearing stage.（3）Limit of water control and amount of nitrogen and potassium application had significant effect on the yield of cucumber.Yield of W₂and W₃treatments was 7.36%and10.29%higher than that of W₁.Yield of N₂treatment was 5.28%and 1.96%higher than that of N₁and N₃,respectively.Yield of K₂and K₃treatments was 2.83%and 2.54%higher than that of K₁,respectively.Through regression analysis,it was determined that the irrigation water limit was 85%θ_F,the nitrogen fertilizer application amount was 381.3 kg·hm^-2,and the potassium fertilizer application rate was 600.7 kg·hm^-2,and the highest cucumber yield was136.14 t·hm^-2.（4）Vitamin C,soluble sugar and soluble protein were used as indicators to reflect the comprehensive quality of cucumber.The quality of cucumber fresh fruit decreased with the increase of irrigation lower limit,and increased with the increase of potassium application.The appropriate amount of nitrogen was beneficial to improve the quality of fresh fruit.In the comprehensive evaluation,W₂N₂K₃treatment obtained the highest comprehensive score of fresh fruit quality of 25.49 points.The best fresh fruit quality can be obtained by the combination of W₂N₂K₃water and fertilizer through range analysis.（5）The correlation coefficients of fresh leaf weight,fresh stem weight and total fresh weight with yield were 0.84、0.89 and 0.92 respectively.Fresh stem weight and fresh leaf weight affect yield by affecting total fresh weight.The correlation between the content of chlorophyll and the yield was the largest at the late fruit bearing stage,which was 0.794.The net photosynthetic rate,transpiration rate,chlorophyll content and yield correlation degree of the fruiting period were 0.726,0.692,and 0.638,respectively,the correlation with the yield is generally greater than the initial fruit and the late fruit bearing stage.（6）There is a contradiction between production,quality and irrigation water use efficiency.The best combination of water and fertilizer determined by analytic hierarchy process is W₂N₂K₃,and the optimal combination determined by entropy method is W₁N₂K₃.Based on the comprehensive evaluation of game theory,the W₂N₂K₃combination of water and fertilizer was determined to be the most favorable for saving water,stable yield and high quality of cucumber in greenhouse.