Growth and Physiology of Grafted Watermelon Seedlings as Affected by Different Light Sources

Watermelon grafted onto bottle gourd and pumpkin rootstock responds to different light sources. Seedlings treated by light-emitting diodes (LEDs) proved to be strong and attained more stem diameter, dry matter contents and growth rate compared to control (white fluorescent lamp). Grafted seedlings have the maximum growth rate, the value of the dry matter contents and the seedling index under LED light source R/B=7:3. Watermelon grafted onto bottle gourd and pumpkin, under LED light source R/B=7:3, seedling vigor indexes were 0.032, 0.033, which are significantly higher than the control. It was observed that increase in blue light component reduces plant height and stem diameter. Moreover, it also helps to improve thickness of palisade tissue, stomata opening, thus increasing the photosynthetic rate and promoting the growth of seedlings. In short, the appropriate LED light source can play an important role in seedlings, among which red and blue LED light source mixed in the ratio of 7:3 is the best optimal light ratio combination for the grafted watermelon seedlings.