Effect of water-deficit stress on fruit yield, antioxidant activity, and some physiological traits of four Iranian melon genotypes

To evaluate the effect of water-deficit stress on the yield, antioxidant activity, and physiological traits of four Iranian melon genotypes (“Khatooni,” “Suski-Sabz,” “Zarde-Tabriz,” and “Shiari”), an experiment was conducted. The irrigation levels were: (1) control (100%ETc); (2) deficit irrigation 66% (66%ETc); and (3) deficit irrigation 33% (33%ETc). The results showed that the yield and relative water content (RWC) significantly decreased in response to an increase in water-deficit stress. The highest yield reduction (60.7%) was measured in Khatooni under 33% ETc deficit irrigation. Water deficit had no significant effect on the Vitamin C content. Among genotypes, the highest value of Vitamin C was seen in Suski-Sabz. Water-use efficiency (WUE) increased under water-deficit stress conditions with higher WUE values recorded in the Suski-Sabz and Shiari genotypes. Significant proline accumulation was detected with increasing water-deficit stress and the highest value of proline was obtained in Shiari under 33%ETc deficit irrigation. The increase in water-deficit stress resulted in higher catalase and peroxidase activities in all genotypes. According to the results, the Suski-Sabz and Shiari genotypes showed the lowest yield reduction respectively, related to high antioxidant enzyme activity and proline accumulation under water-deficit conditions.