Application of Biological and Chemical Fertilizers on Morphological Characteristics, Antioxidant Enzymes Activity, and Sugar Content of Melon Fruit cv. Ahlam Under Different Irrigation Regimes

In order to study the effect of different irrigation regimes, and application of biological and chemical fertilizers on morphological characteristics, antioxidant enzyme activity, and sugar content of melon fruit cv. Ahlam, an experimental split-factorial plots has been done in a randomized complete block design with three replications in Khuonj County in 2018-19. The main factor has been irrigation at 3 levels including 50%, 75%, and 100% of water requirement, with the sub-factor including NPK chemical fertilizer at 0, 60, 120, and 180 kg/ha as well as non-application of Nitroxin biofertilizer along with application of 100% of the recommended amount. Results show that different irrigation regimes, different fertilizer treatments, and their interaction have had a significant effect on some of the studied traits. The combined application of chemical fertilizers with biofertilizers show a significant effect on the number of sub-branches, total plant weight, length and diameter of the most branch, total soluble solids (TSS), the quantity of xylose and fructose sugars and activity of catalase, superoxide dismutase, and peroxidase enzymes. The highest number of sub-branches and plant fresh weight, branch length and diameter are obtained in the chemical fertilizer treatment of 120, and 180 kg/ha with the utilization of Nitroxin fertilizer under 100% water stress. However, it has been observed that biofertilizers has had no significant effect on sugars and enzyme activity in fruit, so that the very best levels of catalase, superoxide dismutase, and peroxidase are obtained within the treatment of 50% of field capacity with 120 and 180 kg/ha of chemical fertilizer without using Nitroxin. In general, it can be concluded that the application of biofertilizers reduce the adverse effects of water stress and the application of chemical fertilizers with biofertilizers hasa significant impact on increasing the studied traits.