Response Of Drought Stress And Comprehensive Evaluation Of Drought Resistance Of Different Cultivars Of Weigela Florida (Bunge)

In order to clear the difference of drought-resistance of four varieties of Weigela, wantto provide the theoretical basis for its rational development and utilization of variousgreen.The drought resisitant of different varieties of Weigela florida (Bunge), Weigelaflorida cv. Red Prince, Weigela florida Bunge A.DC, Weigela‘Red Prince’＋vat, Weigelaflorida cv.Foliia Purpureis, were studed in this paper. Physiological and biochemicalindexes including relative water content(RWC), water saturation deficit(WSD),Chlorophyll content, relative electric conductivity(REC), malondiald ehyde content(MDA),soluble sugar content(WSC), free praline content(Pro), superoxide dismutase(SOD),catalase(CAT), chlorophyll fluorescences were compared under the condition of soil waterstress(CK,5d,10d,15d,20d,25d). Finally, the Comprehensive evaluation of droughtresistance of four cultivated varieties of Weigela florida comprehensive evaluation wereanalysed by principal component analysis and cluster analysis method, using thedetermination of the physiological and biochemical indexes. The main results aresummaried as follow:(1) From the perspective of RWC, the hydraulic of most powerful is Weigela floridacv. Red Prince under drought stress conditions, followed by the Weigela florida cv.FoliiaPurpureis and Weigela‘Red Prince’＋vat the weakest, and in WSD to judge the purpledrought resistance of Weigela florida cv.Foliia Purpureis took the weakest, followed byWeigela‘Red Prince’＋vat, Weigela florida cv. Red Prince ’s strong. The drought led todestruction of the cell membrane systems of every variety, resulting in extravasation rateincreased. The drought-resistance performance of the content of MDA for Weigela floridacv.Foliia Purpureis> Weigela florida (Bunge) A.DC> Weigela florida cv. Red Prince>Weigela‘Red Prince’＋vat. As the drought worsens, four varieties of Weigela florida in theaccumulation of WSC and Pro is a way to plant drought tolerance, Weigela florida cv. RedPrince and Weigela florida cv.Foliia Purpureis with the strong ability of OsmoticAdjustment, Weigela florida (Bunge) A.DC and Weigela‘Red Prince’＋vat is relativelyweak.The latter part of the stress accumulation of Pro didn’t react on Osmotic Adjustment,but which were a large number of accumulation because the plants were hurt. Water deficitcondition, the ability to withstand drought damage by raising the activities of SOD and CAT of Weigela florida cv. Red Prince was more powerful than other varieties. The size ofactivities of SOD and CAT of the other three varieties was in different performance,especially the differences between the activity of SOD and CAT of Weigela‘Red Prince’＋vat was significant.(2) The contents of chlorophyll were decline of varieties of Weigela florida with thedecrease in soil water. As result of the water content caused by falling of plants in leadingroles, the chlorophyll was heightened in the latter part of the stress. Weigela florida cv. RedPrince was less affected on the same composition of drought stress, so it’s slow reaction tothe change of water conditions. Terms of the ratio of chlorophyll to determine the order fordrought-resistance of four species: Weigela florida cv. Red Prince> Weigela floridacv.Foliia Purpureis> Weigela florida (Bunge) A.DC> Weigela‘Red Prince’＋vat. Byanalysis of chlorophyll fluorescence parameters, the loss by heat and fluorescence inabsorbed energy by PSII reaction center of four varieties of Weigela florida was increasedunder different drought, the reduced flow to the photochemical reaction. Meanwhile, theoriginal light energy conversion efficiency and potential activities of PSII were reduced,photosynthetic electron transfer is not working properly. Amony those, Weigela florida cv.Red Prince in photo-inhibition had not occurred during drought stress, Weigela floridacv.Foliia Purpureis took the photo-inhibition to a lesser extent, Weigela florida BungeA.DC and Weigela‘Red Prince’＋vat photo-inhibition largest extent.(3) The drought resistances of the four varieties of Weigela florida (Bunge) wereevaluated by principal component analysis based on the average rate of change of eachplant under drought stress. The drought resistance order follows: Weigela florida cv. RedPrince＞Weigela florida cv.Foliia Purpureis＞Weigela florida (Bunge) A.DC＞Weigela‘Red Prince’＋vat. The results of cluster analysis shows Weigela florida cv. RedPrince was the most drought resistant plants, Weigela florida cv.Foliia Purpureis exhibiteda medium level of drought resistance, Weigela florida (Bunge) A.DC and Weigela‘RedPrince’＋vat had poor drought resistance．...