The Effects Of Water And Fertilizer Coupling On Cucumber Cultivated In Bag With Compound Substrate

The study was aiming to dealing with the problems of lacking of irrigation and fertilization schedule on substrate cultured vegetables,the effects of different irrigation and fertilizer coupling on yield,quality,water and fertilizer use efficiency,nutrient accumulation,nutrient distribution and variation of nutrient absorption of cucumber crop under substrate bag cultivation were investigated.Used principal component analysis and multiple regression analysis to seek the better scheme of irrigation and fertilization based on comprehensive evaluation of yield,quality and fertilizer productivity,nutrient absorption and biomass.The purpose of this study was to find a management method with a high-yield,good-quality and high-efficiency production for the cucumber bag cultivation.‘Bonai 14-3'cucumber was chosen as the experimental cultivar,which were planted in the large-span double-covered plastic greenhouse with the temperature range from 15.1?to 28.4?.Experiment set four irrigation water levels[W1?75%ETc?,W2?100%ETc?,W3?125%ETc?and W4?150%ETc?]and three Yamazaki cucumber nutrient solution formula concentrations[F1?60%?,F2?100%?,F3?125%?].The main results showed as follow:1.Different irrigation and fertilizer coupling treatments significantly affected growth and photosynthesis of cucumber.In the early fruit stage?after treatment 49 days?,plant height showed a parabolic trend which rise first and then fall with the increase of irrigation water,under the same fertilization level.The interaction effect of irrigation and fertilizer on plant height was significant,whereas,it was non-significant difference for stem diameter.The trend of leaf growth rate was first increased and then decreased in W1 and W4 irrigation treatments,which decreased first,slightly rose and then fall under W1 and W4 irrigation conditions.In full bearing stage,Pn was firstly increased and then decreased with the increase of irrigation water under the condition of F1 and F2.If we only considered irrigation conditions,Pn showed a trend of increasing at first and then decreasing with the increase of fertilizer,the effect of fertilization on Pn was significant.If we just took into account fertilizer conditions,Pn decreased gradually with the increased irrigation water,the Pn of W1F1 treatment was the largest and it was 8.99?mol·m^-2·s^-11 higher than W2F1 treatment.2.The accumulation and distribution of total nitrogen,total phosphorus and total potassium in different cucumber organs had different response to different water and fertilizer coupling treatment.The effects of fertilization,irrigation and their interaction on the total nitrogen accumulation of cucumber plant were extremely significant?except for the interaction between irrigation and fertilization was not significant in full bearing stage?.The effect extent of total nitrogen accumulation in the whole plant was as follows:fertilization>irrigation>water and fertilizer coupling.Irrigation level significantly affected the total phosphorus accumulation in the whole plant of cucumber,and the effect of irrigation was greater than those of fertilizer and water and fertilizer coupling.The effects of fertilization,irrigation,and their interaction on the total potassium accumulation of the whole plant were also extremely significant?except the effect of fertilization was not signifi cant in telophase of fruiting stage?.Leaves and fruits were the main organs accumulated nutrient elements in the early fruit stage,vegetative growth and reproductive growth are synchronous,nitrogen accumulation was up to 98.6%.Fruit was the main organ accumulated nitrogen and phosphorus in telophase of fruiting stage and the accumulation of potassium in full bearing and telophase of fruiting stage.In this experiment,total nitrogen accumulation was highest in W2F3 treatment?5652.3 mg/plant?,the total potassium and total phosphorus accumulation was optimum in W3F2 treatment,respectively 1591.1 mg/plant and 7334.6mg/plant.Total nitrogen,total phosphorus and total potassium accumulation showed an increasing at first and decreasing in end and peaked at full bearing stage,1847.5 mg/plant,450.1 mg/plant and 2005.6 mg/plant respectively.Under the same fertilization conditions,the total nitrogen,total phosphorus,and total potassium accumulation of cucumber plants increased at first and then decreased with the increase of irrigation,and the optimal values appeared in W2 or W3 treatments.3.Different treatments have a significant effect on yield,WUE,PFP,element use efficiency and element uptake efficiency.The effect of different water and fertilizer coupling treatment on yield was showed that the yield displayed a downward trend of parabola with the increase of irrigation water.W3F2 treatment had the highest yield?2.75 kg/plant?and W1F2treatment had a maximum WUE?74.92 kg/m³?.Under the same fertilization conditions,WUE showed a decreasing trend with the increase of irrigation volume.The response pattern of PFP to water and fertilizer was different from that of WUE.Increasing the amount of fertilizer applied decreased PFP significantly,F1 was 46.9%and 82.5%higher than that of F2 and F3treatment,respectively.The nitrogen use efficiency ranged from 805.3 to 450.7 kg/kg,and W3F1 had the highest nitrogen use efficiency.Phosphorus use efficiency is similar to nitrogen use efficiency,and potassium use efficiency range is smaller than nitrogen and phosphorus use efficiency.With the increase of irrigation,the phosphorus uptake efficiency showed a downward-looking parabolic trend under the same fertilization treatment,and all fertilization treatments reached the maximum in W3.The uptake efficiency of potassium by cucumber plant was between that of nitrogen and phosphorus,and the mean value of different treatments was 0.45 kg/kg.4.Based on the principal component analysis method,a comprehensive evaluation was made on the coupling effect of water and fertilizer in cucumber.The results showed that the comprehensive evaluation of W1F2 treatment index was the best,followed by W3F2 and W3F1,and W4F3 treatment was the worst.Based on multivariate regression analysis and spatial analysis method,a comprehensive evaluation of the effect of water and fertilizer in cucumber was conducted:The fertilization and irrigation amount keep in 20.0-27.5 g?N:6.58-9.05 g/plant,P₂O₅:4.24-5.82 g/plant,K₂O:9.18-12.62 g/plant?and 42.0-62.0 L,which yield,nutrient absorption and dry weight can reach a maximum value of 90%.The fertilization and irrigation amount keep in 15-17.5 g?N:4.94-5.76 g/plant,P₂O₅:3.18-3.71g/plant,K₂O:6.89-8.03 g/plant?and 54-64 L,which yield,partial factor productivity of fertilizer and nitrate can reach a maximum value of 90%.The fertilization and irrigation amount keep in 18.5-20.5 g?N:6.09-6.75 g/plant,P₂O₅:3.92-4.34 g/plant,K₂O:8.49-9.41g/plant?and 42-46 L,which yield,water use efficiency and dry weight can reach a maximum value of 90%.