Studies On Photosynthetic And Stress Physiological Characteristics Of Four Watermelon Species

The experiment based on two parts of field experiment and greenhouse experiment. Studies on the photosynthetic characteristics, salt tolerance and drought tolerance characteristics of two diploid species and two triploid species of watermelons. We hope that it can provide some theoretic gists and technique measures. From the experiment, we can summarize these conclusion.There are different types of diurnal variations of Pn on different period of watermelons. On growth period, the diurnal variations of Pn present typical double peak curve and there are obvious"siesta"phenomenons. On fructification period, the diurnal variations of Pn present single peak curve except H-6-1.The Pn of two triploid species are higher than two diploid species of watermelon. The LCP and LSP of leaves of four species watermelons are higher, it present their dependence on light. In midday, PSⅡresponse center didn't make use of superfluous light energy and fall under light restrain. After salt and drought treatment to watermelon seedlings, their MDA content and POD activity hoist, SOD activity fall, and PRO hoist earlier and fall later. Based on synthesizing variety of stress tolerance indexes, we can make a conclusion that salt tolerance and drought tolerance of two triploid species of watermelons are stronger.On seedling period, the growth of triploid species are better than the diploid species of watermelon. But on growth period, the triploid species showed the better growth, and their nutrition growth are more quickly than he diploid species; leaves area of the triploid species are bigger than the diploid species species. The change of chlorophyll content are differ with the change of Pn.Based on Photosynthetic physiological characteristic, stress physiological characteristic, yield and quality of watermelons, The mostly indexes of天园无籽一号were better than other watermelon species, then天园无籽二号, and they are excellent species to extend. The stress tolerance of H-6-1 was worse than安农二号, but Pn, yield, Soluble solid content, Vc content of H-6-1 were higher than安农二号, so it is a species good for extendence. The mostly indexes of H-6-1 were worse than天园无籽一号and天园无籽二号, but its seeding and surviving rate were higher than them. On process of selection of watermelon, we must consider aspects of characteristic and bases on requirement and growth condition.