Effect Of Silicon On Drought Resistance Of Phyllostachys Violascens

In order to clarify the mechanism of silicon (Si) in enhancing the resistance todrought stress, the effects of Si on the physiological and biochemical characteristics ofLei Bamboo (Phyllostachys praecox) were investigated under drought stress. The effectsof exogenous Si on growth parameters, physiological and physiological characteristics,antioxidative defenses, and osmotic adjustment substances of Lei Bamboo wereinvestigated under drought stress induced by polyethylene glycol （PEG6000） inhydroponic conditions. The main results were presented as follows:In this study, the influences of silicon fertilization on growth and silicon content ofLei bamboo with hydroponic culture was investigated. Results showed that at60th dayafter silicon fertilization, the biomass increased has no significant difference betweendifferent treatments. Silicon content of bamboo increased as the amount of fertilizerincreased. At180th day, biomass increased was highest with5.4mM treatment, and wassignificantly different from control (CK). At high concentration (7.2mM and9mM), theincreasing biomass tended to decline. At180th day, silicon content of different treatmentsreached stable level, and silicon contents of3.6mM,5.4mM,7.2mM and9mM treatmenthad no significant difference. This suggested that5.4mM is the best treatment for Leibamboo’s growth.Exogenous silicon increased Si content of Lei Bamboo. The difference contentsbetween different part are: leaf＞stick＞root.Bamboo growth and leaf photosythesis were significant inhibited under droughtstress. Compared with the plants treated with PEG alone, the net photosynthesis rate ofthe leaves of drought-stressed bamboo was significantly enhanced with the application ofsilicon. Compared with control(with PEG alone), net photosynthetic rate (Pn),transpiration rate (Tr), water use efficiency(WUE), stomatal conductance (gs) andstomatal limitation value (Ls) were more significantly enhanced but intercellular CO2concentration (Ci) was significantly decreased by Si added. Drought-stress plants with Siapplied had significantly great chlorophyll content, chl a, and chl b content compareswith drought-stressed plants without Si applied.Drought stress changed the activities of superoxide dismutase (SOD), guaiacolperoxidase (POD), and catalase (CAT) in bamboo leaves. Compared with CK treatment,SOD and CAT activities were decreased, and POD activity was increased. Exogenoussilicon obviously increased the activities of CAT and SOD, and decreased the activity ofPOD.The concentration of MDA and proline were also increased significantly by droughtstress, but was decreased by exogenous Si significantly.Microscopic observations revealed that the chloroplast and mitochondria structure inleaves of drought-stressed bamboo were damaged with thylakoid of chloroplastbecoming swollen, and matrix lamella being obscure and arranged disorderly. And drought stress led to obvious plasmolysis. However, exogenous Si improved theultrastructure of the leaves of drought-stressed bamboo with less plasmolysis.It indicated that silicon enhance drought resistance of Lei bamboo.