Effects Of High Temperature On Light Allocation And Antioxidant Activities In Eggplant Seedlings

Eggplant (Solanum melongena L.) is annual herb of Solanaceae and solanum originating fromSoutheast Asia and India. The eggplant is one of the most important vegetables in slack season andone of the most popular wide-spread vegetables. The optimum temperature for eggplant is between25℃and30℃. When the plants are exposed to above35℃conditions, the yield will be reduced to agreat extent. And thus it is worthy to study how eggplant responds to heat stress. In the present study,we determined the semi lethal high temperatures of nine eggplant cultivars, and then subjected2cultivars (with different heat tolerance) seedlings into41℃/36℃(day/night) high temperature, andmeasured heat injury index, leaf chlorophyll concentration, chlorophyll fluorescence parameters andantioxidant enzyme activities. The main results were summarized as follows:We measured the semi lethal temperatures of9cultivars eggplant seedlings. The semi lethaltemperature’ of Heiselvkuqie eggplant’ is lowest, suggesting that it is the most heat sensitive cultivar.‘zaoshouwang NO1’had the highest semi lethal temperature, implying that it is the most heat resistantcultivar. And these results were consistent with their performance of plants under41℃/36℃hightemperature stress.During the early stage of41℃/36℃（day/night）stress, PSⅡPhotochemical quenching（qP）,actual PS Ⅱe fficiency (ΦPSⅡ), relative electron transport rate (ETR), Chla concentration (Chla),Chlb concentration (Chlb), total concentration in eggplant leaves decreased evidently, and moresignificantly in heat sensitive cultivar ’heiselvkuqie eggplant’ plants. This suggested thatphotosynthesis electrons declined significantly.High temperature stress increased electrolyte leakage in eggplant leaves, and more significantlyin heat sensitive cultivar. During the first6d of heat stress, activities of superoxide dismutase (SOD),catalase (CAT) and ascorbate peroxidase (APX) in the eggplant leaves was reduced. After6d of heatstress, activities of SOD, CAT and APX enhanced, and more significantly in heat tolerant cultivar.These results suggested that the heat tolerant cultivar remained higher activities of antioxidant enzymes and might be benefit for ROS scanvege, and leaded to lower electrolyte leakage.