Study On Nutrient Absorption And Techniques For High Quality And Efficient Fertilization Of Three Main Vegetable Varieties In Wuhan

There are many problems in vegetable production in Wuhan,such as excessive fertilization,over-fertilization（regardless of the law of crop nutrient demand and soil nutrient status,unreasonable application proportion of nitrogen（N）,phosphorus（P）and potassium（K）fertilizers）,outdated fertilization methods and so on,which lead to the decline of vegetable yield and quality,increased production costs,deterioration of soil properties and environmental pollution,and serious decline of soil sustainable production capacity.In order to change the above fertilization status and solve the practical problems in vegetable production,this paper selects the new lettuce variety"Huasun"cultivated for stem vegetables and the new vegetable eggplant variety"E eggplant No.2"for fruit vegetables by the Vegetable Research Institute of Wuhan academy of Agricultural Sciences,and the common purple flowering stalk variety"daguzi"for flower vegetables as the materials for research.We studied the optimal fertilization amount and nutrient demand law of the three vegetables by field trials,and developed eggplant water-soluble formula fertilizer and precision fertilization technology,and finally identified the fertilization mode of eggplant and purple flowering stalk as well as the N application form of purple flowering stalk.This study provides theoretical and technical supports for the research and development of special fertilizer and the application of high efficiency fertilization technology for high-yield and high-quality crops.The main results are as follows:1.The best application amount of N,P and K fertilizers for three vegetables.With the increase of N,P and K fertilizer application,the plant height and stem diameter of lettuce,the number of green leaves,bolting number and single bolt weight of purple flowering stalk increased first and then decreased.Fertilization significantly increased the yield of lettuce,eggplant and purple flowering stalk.Compared with no N,P and K application,the yield increases of lettuce were 13.56%～22.03%,15.15%～42.42%and 7.14%～10.32%,respectively;the yield increases of eggplant were10.71%～24.75%,6.20%～14.08%and 2.25%～19.41%,respectively;the yield increases of purple flowering stalk were 18.99%～44.53%,5.26%～15.12%and16.50%～40.52%,respectively.The correlation analysis between fertilization rate and quality index showed that there was a significant positive correlation between N application rate and soluble sugar content,P application rate and Vitamin C content,and K application rate and the contents of Vitamin C and soluble sugar in lettuce;A significant positive correlation was observed in eggplant between N application rate and the contents of nitrate and soluble sugar,P application rate and the K application rate and Vitamin C content,while there was a significant negative correlation between P application rate and nitrate content,K application rate and soluble protein content;In purple flowering stalk,there was a significant positive correlation between N application rate and the contents of nitrate and soluble protein,P application rate and soluble protein content,K application rate and Vitamin C content,but a significant negative correlation between P application rate and Vitamin C content,K application rate and soluble protein content.Based on the analysis of the best yield,best quality and best economic benefit,it is recommended that the best application rates of N,P₂O₅ and K₂O for lettuce are 315 kg/hm²,210 kg/hm² and 285 kg/hm²,respectively.For eggplant,they are 360 kg/hm²,128 kg/hm² and 320 kg/hm²,respectively.While for purple flowering stalk,they are 445 kg/hm²,300 kg/hm² and 360 kg/hm²,respectively.N is the most,K is the second,and P is the least for the best application rates in the three crops.The ratios of the three elements were 1:0.67:0.90,1:0.36:0.67and 1:0.67:0.81 in lettuce,eggplant and purple flowering stalk,respectively.The regression analysis showed that the yield and profit of the three vegetables and the application amount of N,P and K fertilizer were significantly positive correlated.The Vitamin C content of the three vegetables can be selected as the quality index of the regression analysis.2.Balanced fertilization（OPT）promoted the growth,quality and yield of the three vegetables.Under OPT,the stem diameter and stem length of lettuce were the highest,the plant height and apparent leaf area of eggplant were the largest,and the number of green leaves,bolting and single bolt weight of purple flowering stalk were the largest.OPT improved fruit quality.Compared with other treatments,OPT significantly increased the content of vitamin C,soluble protein,soluble sugar and amino acid of lettuce stem,vitamin C content of eggplant fruit as well as the soluble protein content of purple flowering stalk.However,the nitrate content of lettuce stem decreased under OPT.Furthermore,the yields of lettuce,eggplant and purple flowering stalk were the highest under OPT,while the yield under other treatments decreased by 14.08%～37.29%,11.04～40.97%and 19.30～42.21%respectively compared to OPT.3.Absorption and accumulation of N,P and K nutrients in three vegetables.Under OPT,the total amount of N,P and K absorbed and accumulated from the soil during the whole growth period of lettuce were 36.18 kg/hm²,5.07 kg/hm² and 55.41kg/hm²,respectively;146.72 kg/hm²,70.90 kg/hm² and 261.43 kg/hm²for eggplant,respectively,and 338.98 kg/hm²,82.72 kg/hm² and 329.32 kg/hm² for purple flowering stalk,respectively.The nutrient accumulations of N,P and K in lettuce was leaf>stem>root.The N accumulation for eggplant was fruit>leaf>stem>root,for P and K were fruit>stem>leaf>root.The nutrient accumulations of N,P and K in purple flowering stalk was stem leaf>bolt>root.In the whole growth period,the absorption of N,P and K by purple flowering stalk is the most,the economic benefit is the best,eggplant is the second,and lettuce is the least.The agronomic efficiency of N and K was eggplant>purple flowering stalk>lettuce,and the agronomic efficiency of P was eggplant>lettuce>purple flowering stalk.The amount of N,P and K absorbed by 1000 kg lettuce stems were 2.44 kg,0.37 kg and 3.73 kg,respectively,and the absorption ratio was 1:0.14:1.53.The amount of N,P and K absorbed by 1000 kg fresh eggplant were 1.50 kg,0.85 kg and 2.65 kg,respectively,and the absorption ratio was 1.00:0.57:1.77.The amount of N,P and K absorbed by1000 kg vegetable bolt were 7.93 kg,1.93 kg and 7.70 kg,respectively,and the absorption ratio was 1.00:0.24:0.97.4.High efficiency fertilization technology and effect of three vegetables.Precise Drip Irrigation and fertilization technology for eggplant:the water-soluble formula fertilizer is applied by drip irrigation in the whole growth period for 6 times.Fertilizers were applied each time within 3-5 days.The fertilizer concentration is 2.50g per liter of water,which has good yield,quality and economic benefits.For purple flowering stalk,hole spraying is better than spraying,and spraying is better than watering during fertilization.The application of different forms of N fertilizers can promote the increase of bacteria number,fungi and actinomycetes in rhizosphere and non rhizosphere soils of purple flowering stalk.Moreover,the performance is different with the growth period.Before the rosette stage,ammonium N can significantly promote the number of bacteria,fungi and actinomycetes in rhizosphere and non rhizosphere soils.However,nitrate N is better after the main bolting stage,and amide N has no obvious effects in the whole growth period.