Morita Seedless Impact On Physiological And Ecological Characteristics Of Salt Stress

Salinity is considered one of the most important environmental factors that affect crop yield and quality. In the present study, we investigated the effect of salinity stress on leave photosynthetic and water physiology under field condition as well as the quality and quantity of Vitis vinifera L. cv. Centennial Seedless. The results show:1. The effect of salinity stress on fruit quality and yieldThe results showed that the number of fruit, berry weight, ear weight, plant yield and yield per mu decreased with the increase of salt concentration. In addition, ear sizes and berry sizes were decreased under salt stress. At the same time, the total sugar content and total acidity of fruit increased, but vitamin C contents decreased.2. The effect of salinity stress on photosynthetic physiologyOur results showed that the net photosynthetic rate decreased with the increase of extent of salinity stress. However, the reasons that lead to this declination can be attributed to either stomatal limitation or non-stomatal limitation. Slight salinity stress (L, M) lowered net photosynthetic rate mainly through stomatal limitation. Under severe salinity stress (H), the reduction of net photosynthetic rate was due to non-stomatal limitation.Salinity stress reduced apparent quantum yield (AQY) and light compensation point (LCP), whilst increased the light saturation point (LSP), indicating the decrease of light utilization capacity. Maximum carboxylation rate of leave also declined under salinity stress, probably due to the reduction of Rubisco content and/or activity. The results of chlorophyll fluorescence measurements showed that maximum photochemical efficiency (Fv/Fm) decreased under salinity stress, suggesting permanent photoinhibition could be of importance to the declination of photosynthetic rate. In additional, the reducing content of chloroplast a, b and total chloroplast content also can account for the decrease of photosynthetic capacity.3. The effect of salinity stress on water physiology and osmotic adjustmentResults showed that the pre-dawn water potential decreased with the increase extent of salinity stress, suggesting the concurrent water stress of salinity treated plants. Under salinity stress, osmotic adjustment exerted to regulate water balance as indicated by the increased content of proline and soluble sugar. Among all treatment, the increase content of proline is more significant than the increase of soluble sugar. Based on this observation, we postulated that of the2most important osmotic adjustment substances, proline played an more important role in osmotic adjustment than that of soluble sugar.In conclusion, our study show that Vitis vinifera L. cv. Centennial Seedless possesses salinity tolerance since it can grow even when suffering severe salinity stress by regulating photosynthsis and water physiology. However, fruit yield and quality decreased as a result of salinity stress.