Study On Irrigation And Nitrogen Management Techniques On Facility Loofah Under Application Of Fertigation

In recent years,the fertigation technology has been widely promoted and applied,but faced with problems such as backward irrigation and fertilization system,the technical advantages can not be fully played.Water and nitrogen are the key factors affecting crop growth and production.In order to optimize the water and nitrogen management mode of luffa under the application of fertigation,this paper took "Xutongyu Luffa" as the test material,using drip irriagtion matrix cultavation management,study the effects of different water-nitrogen coupling and nitrogen fertilizer based topdressing ratio（basal-topdressing ratio）on the growth,physiology,yield and quality of luffa,and get better water and nitrogen management model by similarity to an ideal solution（TOPSIS）based on entropy weight method.The following conclusions are mainly obtained:（1）Set two irrigation levels（the irrigation low limit at flowering and fruiting period was 75%and 65%of saturated water content of matrix,marked as W1 and W2,respectively）and three N levels（10.0,8.5 and 7.0 g/plant,marked as N1,N2 and N3,respectively）to study the effects of water and nitrogen interaction effect on the growth,physiology,yield and quality of the loofah.The results showed that under the same nitrogen application level,the vine length,vine diameter,leaf number and leaf area per plant of W1 treatment were increased compared with that of W2 treatment.With the decrease of nitrogen application rate,the vine length,leaf number and single leaf area decreased,while the vine diameter increased first and then decreased.The relative chlorophyll content（SPAD）,net photosynthetic rate,stomatal conductance and transpiration rate of leaves were decreased by decreasing nitrogen application rate.The lower irrigation low limit increased fruit shape index and commodity index.The commodity rate of W1N2 treatment was the highest（86.10%）,and the commodity index of W2N2 treatment was the highest（55.68%）.Different water and nitrogen combinations had no significant effect on soluble protein content.Vitamin C content in W2N1 treatment was significantly lower than that in other treatments.The soluble sugar content was N2>N3>N1,and W1N2 was the highest,which was 20.38 mg/g.There was no significant difference in the number of melons per plant among different treatments,but there was a significant difference in yield.The yield of W2N2 treatment was the highest,which was 1.93 kg/plant.The lower limit of irrigation and the reduction of nitrogen application rate reduced the irrigation amount.W2N2 treatment had the highest water production efficiency of 67.63 kg/kg.（2）On the basis of a total N application rate of 10.0 g/plant,9 groups of treatments（T1～T9）with different proportions of N base application,topdressing at leaf-pumping stage and topdressing at flowering and frustling stage were set up to study the effects of nitrogen basal-topdressing ratio on the growth,physiology,yield and quality of luffa.The results showed that the days of luffa harvest increased firstly and then decreased with the backward nitrogen application rate,and T6 treatment（1:1:8）was the longest,41 days,15 days more than T9 treatment（0:0:10）.High nitrogen application rate of base fertilizer is easy to cause the plant to grow excessively.Base fertilizer without N fertilizer significantly inhibited plant growth.The SPAD value of leaf was decreased by the decrease of nitrogen application rate in the early stage,but the difference was small in the flowering and fruiting stage.The higher proportion of nitrogen application at flowering and fruiting stage would keep the net photosynthetic rate,stomatal conductance and transpiration rate at the end of fruiting stage.The contents of soluble sugar,soluble protein and vitamin C in luffa increased firstly and then decreased with the increase of nitrogen application rate.The contents of soluble sugar and soluble protein in T6 treatment were the highest,and the contents of vitamin C in T5 treatment（2:0:8）were the highest.T4 treatment（2:1:7）had the largest number of melons per plant（11 melons per plant）.T6 treatment had the highest yield per plant（2.01 kg/plant）,which was 30.29%higher than that of T1（4:0:6）.The number of melon and yield per plant in T9 treatment were the lowest.（3）TOPSIS method based on entropy weight method was used to form evaluation index system in terms of economic benefit,ecological benefit and quality.Comprehensive evaluation and analysis were conducted on each treatment of water-nitrogen coupling test and nitrogenous fertilizer base comparison test respectively.The results showed that W2N2 treatment（irrigation low limit 65%θFC+N application rate 8.5 g/plant）had the highest comprehensive evaluation value and was a suitable combination of water and nitrogen.W1N3（irrigation low limit 75%θFC+N application rate 7.0 g/plant）had the lowest comprehensive evaluation value.The comprehensive evaluation ranking of nitrogen basaltopdressing ratio treatment increased first and then decreased with the increase of nitrogen application rate,and the best nitrogen basal-topdressing ratio was 1:1:8.