Evaluation of growth, water, nitrogen, potassium use efficiency and nitrate ‎reductase activity in grafted melon “Khatooni” under soilless culture

Vegetative traits, chlorophyll content, water use efficiency, nitrogen, potassium and nitrate reductase activity of leaves and root tip were investigated in composition of the melon 'Khatooni' on squash cultivars Ace and Shintozwa under greenhouse conditions. Treatments consisted of melon grafted on squash, melon on melon, squash on melon, squash on squash, melon and squash own-rooted. Results showed that melon grafted on Shintozwa  had stem length (408.3 cm), leaf number (38.56), total leaves fresh weight (156.7 g), total shoot fresh weight (132.7 g), leaf area (18517.6 cm2), biomass (247.5 g), leaf dry matter (14.19%), shoot dry matter (7.96%) and root dry matter (17.46%) more than Ace. Grafted melons on both rootstocks were increased water, nitrogen and potassium use efficiency. The amount of total nitrogen and leaf nitrate on Ace rootstock was more than Shintozwa. The leaf ammonium on Shintozwa rootstock was more than Ace. A high nitrate reductase activity of leaves was obtained on melons grafted on Ace rootstock. Nitrate reductase activity in roots was higher than the leaves especially in the case of grafting. Root nitrate reductase activity was demonstrated a negative correlation with shoot length, biomass, leaf fresh weight, shoot fresh weight, leaf total area and root dry matter. Grafted melons totally contain large amount of organic nitrogen were compared to non-grafted, which it related to nitrate reduction and high nitrate consumption.