Optimization Of Different Ratio Of Nutrient Solution And Cultivation Mode Of Chinese Leek In Hydroponic Culture

Chinese leek（Allium tuberosum Rottler ex Sprengle）is a traditional vegetable in China which is popular with consumers in the north of China and has rich nutritional and medicinal value.Soil cultivation and years of continuous planting are the mainly planting pattern for leek,which lead to the occurrence of diseases and pests.At present,the use of pesticides or the use of increased amounts is the main control measure,which affects the food safety and sustainable development of leek production.It has been proved that the hydroponic leek technology of soilless cultivation is an effective measure to solve the problem of diseases and pests in leek production.However,the hydroponic leek cultivation is currently in initial stage,and its cultivation nutrient solution management and cultivation mode is not mature.Based on this,further study on the optimization of hydroponic leek planting mode provides theoretical and practical basis for the safe production of leek.The main results are as follows:（1）Screening of hydroponic nutrient solution suitable for leek cultivars.Four varieties of 791 Kuanye Xuejiu,Pingjiu No.4,Dajingou You Line and Haijiu No.2 were selected.The growth,quality and yield of leek were identified,the results showed that length and width of leaves,stem diameter,growth rate and production of 791 Kuanye Xuejiu and Pingjiu No.4 were superior to other hydroponic leek cultivars;The chlorophyll content of Dajingou cultivar is the highest than other hydroponic leek cultivars;In terms of nutrients,Haijiu No.2 had the highest Vc content at 39.23mg/100g,and 791 Kuanye Xuejiu had the lowest content;The soluble sugar content of Dajingou was the highest at 14.77%,the second on the list is Haijiu No.2,and other hydroponic leek cultivars had no significance;The crude fiber content of different hydroponic leek cultivars was measured and the result indicated that Pingjiu No.4 had the highest content;The soluble protein of Haijiu No.2 was the highest,and it was not significantly different from Dajingou You Line and Pingjiu No.4;In addition,the detection of nitrate content indicated that Haijiu No.2 had the lowest content at 1924.36mg/kg,and other cultivars were in the range of the safety.Considering the growth indexes,production,quality and economic benefits,this experiment manifested that Pingjiu No.4 was more suitable for large-scale production of hydroponic leek.（2）The effects of different nutrient solution formula on hydroponic leek.The results showed that the growth,quality and production indexes of leek increased first and then decreased with the decrease of KNO₃concentration in nutrient solution,and the indexes of N4 treatment nutrient solution ratio were the highest;The length and width of leaves,stem diameter,plant height and leaves numbers of N4 treatment were significantly higher than those of N1,N2 and N3 treatment,and increased 19.89%,35.82%,50.46%,15.98%,27.50%,respectively,compared with mock treatment;The chlorophyll content was significantly higher than other treatments;The contents of crude fiber,Vc,soluble sugar and soluble protein increased significantly compared with other treatments;The nitrite content was 2420 mg/kg,which was higher than that of N1,N2 and N3 treatment,but lower than that of mock group,which was within the range of safety;The yield of N4 was 4751.21 kg that was significantly higher than other treatments.In conclusion,the hydroponic leek indexes of growth,nutritional quality and yield of were significantly higher than other treatments.Therefore,the group N4 was selected for the subsequent optimization experiment of hydroponic leek cultivation mode.（3）Optimization on the novel hydroponic leek cultivation mode.A new double-layer planting frame for hydroponic leek was designed to evaluate the different hydroponic leek cultivars indexes.The novel hydroponic leek cultivation mode（double-layer hydroponic cultivation frame）and flat hydroponic leek cultivation（deep flow cultivation）were performed to study the growth and quality of hydroponic leek.The results showed that the temperature,flow rate,light intensity and nutrient solution formula in double-layer planter could meet the growth needs of leek.The indexes of leek in P2 treatment group were the highest in the hydroponic cultivation mode（N4nutrient solution formula+double-layer hydroponic cultivation rack）.The length and width of leaves,stem diameter,plant height,leaves numbers and chlorophyll content were significantly higher than group P1（N4 nutrient solution formula+plane hydroponic culture）;The crude fiber content,vitamin C content,soluble sugar content and soluble protein content of group P1 were 45.00%,43.66 mg/100g,291.02μg/Mg and 370.00 mg/100g,respectively.The nitrite content was 2420 mg/kg that was significantly lower than group P1;The yield was 7390.43 kg that was significantly higher than the cultivation mode of group P1.In conclusion,the novel hydroponic leek cultivation mode composed of hydroponic leek double cultivation frame and the optimal nutrient solution formula can increase the quality and safety of hydroponic leek,improve the space utilization rate of leek cultivation,and effectively solve the safety problems of traditional leek cultivation mode.The application of this model will provide theoretical basis for the further development of Chinese leek in hydroponic cultivation.