Hydroponic cultivation refers to plant roots directly in the nutrient solution without substrate cultivation.The most famous and common hydroponics is nutrient film technique(NFT),its working principle:Make a very thin layer of nutrient solution(0.5-1.0cm) cycle through the crop root,not only ensure continuous water and nutrient supply for crop,but also fresh oxygen supply for the root.NFT cultivation method greatly simplifies the irrigation technology,need not calculate crop water requirement everyday,and can ensure balanced nutrients supply.NFT cultivation method takes part roots from the soil,avoiding all sorts of soil borne disease,also no need for soil disinfection.