Optimizing Efficient Healing Environmental Parameters Of Watermelon And Melon Grafted Seedlings

Rootstock grafting improves resistance to the soil borne diseases,and is widely used in seedlings production. Environmental factors such as light intensity, temperature and humidity play an important role on survival rate, and quality of grafted seedlings. This study focus on the standardization of optimum environment management parameters during healing period,we hope it will provide scientific basis for the management and production of watermelon and melon grafted seedlings. The main results are described below:1. Study of environmental factors during healing period of watermelon and melon grafted seedlings. The healing period of grafted watermelon seedlings can be divided into three stages(0d~3d, 4d~6d, 7d~8d). This experiment investigated the effect of humidity, temperature, and light intensity combinations during the healing period, on the survival rate and growth of grafted watermelon. The results show that highest survival rate and the best seedling quality of watermelon was attained at relative humidity of 95%(0d~3d), 85%(4d~6d), 75%(7d~8d), temperature of 28/23℃(0 d~3 d), 25/20℃(4d~6d), 23/18℃(7d~8d), and light intensity of 75μmol·m-2·s-1(0d~3d), 150μmol·m-2·s-1(4d~6d), 225μmol·m-2·s-1(7d~8d) after grafting. It indicates that these environmental management parameters were suitable for healing management of grafted watermelon and melon seedlings.2. Experiment of evaluating rootstocks quality under different combinations of LED light. Bottle gourd and pumpkin seedlings were grown under LED light of R/B=7:3, using light intensity of 50 μmol·m-2·s-1, 100 μmol·m-2·s-1, and 150 μmol·m-2·s-1, whereas, fluorescent light was used as control. Seedlings show bad morphological characteristics under LED light of 50 μmol·m-2·s-1, while bottle gourd seedlings under 100 μmol·m-2·s-1and pumpkin seedlings under 150 μmol·m-2·s-1 performed well.3. During the study of healing efficiency under different light sources, we found that the survival rate of grafted watermelon seedlings under LED light sources were better compared with the seedlings grown under fluorescent light by setting different LED light qualities(CK: WFL, T1: R/B=7:1,T2: R/B=7:2,T3: R/B=7:3)during healing period. Additionally, LED light source of R/B=7:3 has excellent impact on seedling quality. The result of another grafted watermelon experiment conducted under different light sources and intensity show that the optimal sequence for graft healing: LED light sources>Fluorescentlamp>Dark. LED light of different intensity were applied to grafted watermelon during the healing period, indicating that light intensity of 50 μmol·m-2·s-1 was enough to accelerate graft healing.