Physiological Effects Of Exogenous Chitosan On Cucumber Seedlings Under Salt Stress

In this experiment, the common facilities cucumber cultivars "Jinyou1" as the test material, salt-sensitive species,in the salt stress (100mmol/L NaCl) conditions using different concentrations of CTS(50,100,150,200,250mg/L) on seed processing, its germination characteristics were studied, the germination under salt stress physiological characteristics of cucumber were summed up, aimed at the identification, screening and improve its salt tolerance to provide a frame of reference. In addition, based on the preliminary experiments in our laboratory, focusing on the different concentrations of CTS (50,100,150,200,250mg/L) effect on the morphogenesis and physiological biochemical characteristics of cucumber seedlings under salt stress (200mmol/L NaCl), in order to clear the effects of salt resistance of cucumber seedlings which CTS induced, in order to improve the salt resistance cultivation of vegetable crops to provide more ideas and methods, for the research and development of formulations of exogenous chitosan to improved salt Tolerance of Cucumber and provide theoretical and practical basis. The main results are as follows:1Low concentrations of CTS treatment significantly improves the cucumber seed germination rate, germination index, vigor index. CTS treatment on seed hypocotyl growth has a significant promoting, and there is no obvious mitigation in radicle length, weight and number of lateral roots.2Under salt stress (200mmol/L NaCl), the index of cucumber seedlings morphological analysis showed:CTS significantly promote the growth of cucumber seedlings,and150-200mg/L CTS induction treatment is best.3Under salt stress (200mmol/L NaCl), the impact of CTS on photosynthesis of cucumber seedlings under salt stress showed that:CTS treatment improves the cucumber leaf chlorophyll content, chlorophyll content obviously increases and then decreases with the increase of concentration of chitosan,under150mg/L CTS treatments, chlorophyll reached the highest content in the eighth day, increased by17.7%respectively compared with the control.4Under salt stress (200mmol/L NaCl), the impact of CTS on membrane lipid peroxidation levels of cucumber seedlings under salt stress showed that:in the first8,13days under salt stress the electrolyte leakage, respectively lower at the concentration of100,100-200,100-150mg/L, the maximum reduction values were35.5%,55.3%,53.2%. With increasing concentration of CTS, MDA content decreased first and then increased. In the first three days after salt stress, high concentrations of the CTS treatments, MDA content was higher than the control, increased up to19.3%, showing a very significant difference. But in the first eight days of salt stress, treated with100mg/L CTS, MDA content in cucumber leaves showed a mixmian,. compared with the same concentration treatment in the3days and13days respectively lower by35.1%,36.3%. It is conculuded CTS alleviate the damage on cucumber seedlings not only have a relationship with salt stress concentration, there is a certain timeliness.5Under salt stress (200mmol/L NaCl), the impact of CTS on osmotica content of cucumber seedlings under salt stress showed that:for proline content in salt stress, in the first8,13days,Pro concent was the highest at the concentration of150mg/L CTS treatment, are significantly higher than the control, respectively up to27.9%,21.4%,30.2%. Except of50mg/L CTS on soluble sugar content (stress after3rd day), low concentrations of CTS reducing soluble sugar content of cucumber, high concentrations of CTS increased soluble sugar content. Stress post (stress after8th day,11th day), soluble sugar content increased gradually with the CTS concentration increased (except of8th day, on the50mg/L CTS). The role of aging from CTS, the later (stress after13th day) results to be significantly better than the previous (stress after3rd day).