Effects Of Nutrient Solution Management Methods And Nitrogen Forms On The Growth And Tipburn Incidence Of Lettuce In Nutrient Film Technique

Effects of nutrient solution management methods (flow position control, solar radiation control, electrical conductivity control, time control) and nitrogen forms (total N was13.3mmol·L-1, the ratios of NO3--N/NH4+-N were3.93:1,5.65:1,9.23:1,21.12:1) on the growth and tipburn incidence of lettuce (Lactuca sativa var. crispa L.) cultivated in NFT were studied to provide the scientific guidance for the lettuce production in NFT. The main results were as follows.(1) Under the period of high solar radiation in NFT, with solar radiation control, growth and quality of lettuce were improved, the NO3--N content was decreased, the absorption of Ca2+content was promoted in leaves, and the tipburn incidence was significantly decreased.(2) Results shows that under the period of low solar radiation in NFT, with time control, the fresh weight and dry weight were improved in the leaves and roots, the NO3--N content was decreased, the Ca2+content in the inner leaves was decreased, but there was no significantly effect on the tipburn incidence.(3) With the treatment of NO3--N/NH4+-N was5.65:1, the fresh and dry weight were improved, the NO3-N content, Vc and tipburn incidence were decreased under the condition of nitrogen forms.In a word, the growth was influenced by the solar radiation, in the period of high solar radiation, solar radiation control was suit for the NFT, the production and quality were improved by the time control in the low period. The research of the nitrogen forms showed that, the production was improved, and the tipburn was decreased in the the treatment of NO3--N/NH4+-N was5.65:1.