Morphological and productive response of melon to fertilizer treatments on land of low fertility

Limited soil fertility and unfavorable climatic conditions significantly affect vegetable production, which requires the application of innovative fertilization strategies. In this research, the influence of organic fertilizer based on plant extracts containing phenolic compounds and phytohormones on the productive and morphological characteristics of melon (Cucumis melo) grown on acidic and poorly supplied soil (pH 3.74, humus 2.4%) was investigated. The experiment was set up in 2024 on the experimental field of the Institute of Vegetables in Smederevska Palanka according to a random block system in three repetitions. The treatments included one (Tr1), two (Tr2) and three (Tr3) fertilizer applications, as well as a control without fertilization. The results showed no statistically significant differences in fruit weight between treatments (1.03-1.23 kg). However, the number of fruits per plant was significantly higher in Tr3 (24), while Tr1 had the highest number of lateral branches (23.80). The largest peel thickness was determined in Tr2 (0.51 cm), which may contribute to better post-harvest durability of the fruits. The highest chlorophyll content was measured in the control variety (65.43 SPAD units), while there were no significant differences in sugar content between treatments (11.31-11.97 ºBrix). Correlation analysis showed a positive highly significant relationship between fruit mass and sugar content (r = 0.41**), while the number of fruits and the number of side branches were negatively related (r = -0.31**). The results indicate that organic fertilizer based on plant extracts can improve certain productive properties of melon in nutrient-poor soil conditions. Further research is needed to optimize the application strategy in different agroecological conditions.