| In order to investigate the Physiological and ecological influence of different nitrogen & potassium additions, and shading levels on the seedling of Jatropha curcas L., as well as to observe their responses to drought stress in the Panxi dry valley, the experiment of J. curcas L. seedlings cultivation were conducted in multi-cavity container tray which air-cutting roots. The results were as follows:(1) Leaves of J. curcas L. seedlings have strong water-retention capacity, while soil relation water content (SRWC) of J. curcas L. seedlings decline 78.71% after stop water supply for 8 d, the relative water content of leaves (LRWC) only decreased 12.45%, leaf saturated deficit value LWSD only increased 55.60%. Its stomatal is very sensitive to water condition of seedling-breeding, it have stronger regulation ability to transpiration, water content of seedling-breeding decline from 21.07% to 11.97% after stop water supply 2 d, meanwhile, the transpiration rate (Tr) has dropped 76.13% and stomatal conductance (Gs) dropped 92.58%. Ability of J. curcas L. seedling of carbon assimilation, Light energy transformation and the electronic transmission is decreased under drought stress, but its water use efficiency is increased under moderate drought stress. Dark respiratory rate (Rd) of J. curcas L. seedling is maximum under moderate drought stress and then sharply decreased, dark respiratory rate increased slightly in extreme drought condition. Content of soluble sugar (SS), soluble protein (SP), free proline (Pro) and carotene (Car), and activity of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) is improving in drought initial, and malondialdehyde (MDA) content is very low and remained stable in their under their combined action. Because content of soluble sugar (SS), soluble protein (SP), free proline (Pro) and carotene (Car), and activity of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) is decreased later drought, the malondialdehyde content rapidly rising.(2) Optimum nitrogen application improve matrix water content of J. curcas L. seedling, the relative water content (LRWC) and keep water ability of leaves. In enough moisture conditions, optimum nitrogen application raise photosynthetic pigment content, carbon assimilation, light capacity, electronic transmission rate, light utilization efficiency and respiration rate, reduce its water use efficiency. Decreasing speed of its photosynthetic pigment content, carbon assimilation, light capacity, electronic transmission rate and light utilization efficiency is decreasing under drought stress J. curcas L. seedlings of optimum nitrogen application, in enough moisture conditions, optimum nitrogen application improving activity of superoxide dismutase, catalase, peroxidase and content of soluble sugar, soluble protein, free proline, carotene, thus reduce malondialdehyde content of J. curcas L. seedling. In water deficit conditions, decline speed of activity of superoxide dismutase, catalase, peroxidase and content of soluble sugar, soluble protein, free proline and carotene is decreased, lower Malondialdehyde content rising speed, and reduced relatively content of Malondialdehyde content.(3) Optimum potassium application improve matrix water content of J. curcas L. seedling, the relative water content (LRWC) and keep water ability of leaves. In enough moisture conditions, optimum potassium application raise photosynthetic pigment content, carbon assimilation, light capacity, electronic transmission rate, light utilization efficiency, and decline its respiration rate and water use efficiency. Decreasing speed of its photosynthetic pigment content, carbon assimilation, light capacity, electronic transmission rate and light utilization efficiency is decreased under drought stress J. curcas L. seedlings of optimum potassium application, In enough moisture conditions, optimum potassium application improving activity of superoxide dismutase, catalase, peroxidase and content of soluble sugar, soluble protein, free proline, carotene, thus reduce Malondialdehyde content of J. curcas L. seedling; In water deficit conditions, decline activity of superoxide dismutase, catalase, peroxidase and content of soluble sugar, soluble protein and free proline, carotene decreasing speed, malondialdehyde content is lower and rising speed is little, and relatively reduced the content of malondialdehyde content.(4) Shade reduces the relative water content of leaves and leaf water ability of J. curcas L. seedlings. Shade reduced ability of carbon assimilation, light capacity, electronic transmission rate, light utilization efficiency, respiration rate and water use efficiency is declined in Normal illumination and moisture conditions. Improve its reducing speed photosynthetic pigment content, carbon assimilation, light capacity, electronic transmission rate, light utilization efficiency and water use efficiency under Normal illumination and water drought stress, J. curcas L. seedlings Shade increased speed of decline of activity of superoxide dismutase, catalase, peroxidase and content of soluble sugar, soluble protein and free proline, carotene in normal illumination and water deficit conditions, improved malondialdehyde rise speed and its content.In summary, the leaves of J. curcas L. seedlings have strong water-retention capacity, which maintains better moisture under the droughty state, the response strategy for drought stress might be by controlling the water consumption and water self-regulation to maintain basic life activities, different nitrogen & potassium level and different shading measures had remarkable regulating effect of moisture physiology, which can remarkably improve the drought resistance of J. curcas L. seedlings, although couldn't change the trend under the drought stress. Appropriate nitrogen & potassium on the seedlings of J. curcas L. had a positive impact in the arid environment moisture status, photosynthesis, osmotic adjustment Antioxidant metabolism, and improve the drought resistance. The seedling shade adaptation into the full light after 15 d, the moisture in the moisture status, photosynthesis, osmotic adjustment antioxidant metabolism were adversely affected, reduced the J. curcas L. seedlings ability to withstand drought.
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