Study Of Cultivation Method And Water And Fertilization Management On Soilless Cultivated Cotton Seedling

The key technology of soilless-cultivated cotton seedlings(SCCS) including different nutritive area, water supply and concentration of nutrient solution in the progress of SCCS culture were studied in this experiment. The effects of these subjects on the development of SCCS were studied morphologically and phsiologically. The results are as follows:1. The growth and development of the above ground of traditional soil-pot cotton seedlings were significantly faster than that of SCCS because of lager nutritive area. However, the root dry matter, R/C and root vigor of soil-pot cotton seedlings were inferior to those of SCCS. Among the seedlings of different hole-plug treatments, at leaf age of 2, the LAI and plant height of 176-hole treatment were higher than seedlings of 120-hole treatment, which suggested the disadvantage of small nutrient area. The root vigor, R/C ratio, and the content and accumulation of N, P and K in root increased while the nutrient area decreased. The transplanting survive rate of cotton seedlings of all treatments were acceptable.2,SCCS were sensitive to the water content in media. The different water supply significantly affected the growth and physiological and biochemistry procedure of SCCS. Less water supply significantly inhibited growth of SCCS. The dry weight of stem, leaf and whole plant decreased significantly, while root dry weight increased. The height, diameter of stem, numbers of leaf and leaf area significantly reduced by less water supply; but R/C, ratio of stem diameter to plant height, root vigor, chlorophyll content, proline accumulation, soluble protein content, free amino acid content in cotton leaf increased apparently. All these changes of morphological and physiological characteristics increased stress tolerance of SCCS after transplanting. With less water supply, the membrane injure increased with the incresing MDA content. However The activities of SOD, POD and CAT increased with the decreasing water supply, which leading to lowere EC. After transplanting, SCCS of 50% RWC water content treatment grew well, SCCS of 40% RWC treatment did not be transplanted because of few qualified plant. It suggested that the suitable water content range for SCCS is about 50% to 70% RWC.3.With the concentration of nutrient solution increasing, the growth of the above ground of SCCS was accelerated, while the R/C, root weight, root vigor and chlorophyll content decreased. The increasing of concentration of nutrient solution promoted N,K absorption of SCCS. When the concentration of nutrient solution was above 2‰, N accumulation increased significantly, while P and K accumulation did not. Because of low temperature, there was no significant difference among the survive rates of SCCS of different treatment after transplanting, although the groth of SCCS of 2%o treatments seemed better. It suggested that the suitable concentration of nutrient solution for SCCS should be less than 2‰, considering about the cost and security of cotton seedling cultivation.