Drought stress mitigation with humic acid in two Cucumis melo L. genotypes differ in their drought tolerance

Different responses of two melon (Cucumis melo L.) genotypes (Semame, drought and salt-tolerant and Ananas, drought and salt- sensitive) to drought stress with or without humic acid ( HA) treatment were studied. The experiment was carried out under greenhouse conditions. The experimental design was two factorial randomized block with 4 replicates. HA treatment increased the shoot fresh and dry weights and leaf area of both genotypes under drought stress. HA stimulated accumulation of K and Ca ions, chlorophyll (SPAD value) and antioxidant enzyme activity (superoxide dismutase-SOD, catalase-CAT and glutathione reductase-GR) in both genotypes. This effect was more clear in the Semame genotype than in Ananas. As a result, HA treatment has been proved to influence the ability of melon genotypes to cope with drought stress and to increase their tolerance.