Abstract: In this experiment, the effects of four substrates on growth of stock (Lagenaria leucantha Rusby.,L. siceraria Standl.)and watermelon grafted seedling. It was found that the stock seedling was strong with low hypocotyl length, and the leaf growth rate of graft seedling was high when cultivated in ‘Golden 3’ and ‘Golden 1’ substrates, which were ideal substrates. The graft seedling showed low disease rate and high survival rate when cultured in ‘Zhongci 1’ substrate, but it was difficult to manage the water. The seed germination rate of stock in ‘Fafard’ substrate was higher than other three ones, but it was necessary to add fertilizer in middle and late growth stage for the lack of nutrition．

Key words: substrate, grafted seedling, watermelon, seedling growth index