Effect of zinc and potassium humate spraying on growth and yield of tomato (Solanum lycopersicum L.)

This study was carried out in a greenhouse associated to the College of Technical Agriculture in Al-Musayyab (32°36′59″ N, 44°22′25″ E) during the 2024-2025 growing season. The objective was to assess how commercial potassium humate fertilizer (PowHumus WSG 85) at five levels (0, 10, 15, 20 and 25 mL L-1) and zinc spray at three levels (0, 10 and 20 g L-1) interacted to enhance S. lycopersicum L. plant growth and productivity. The experiment was laid out in a randomized complete block design (RCBD) with three repetitions, using a drip irrigation system. Seedlings (40 days old) were transplanted at 40 cm spacing. Two foliar spraying were applied: the first 20 days after transplanting and the second, 20 days later. Measurements included: plant height, total number of leaves, number of flower cluster, number of flowers, number of fruits, fruit weight and total yield per plant. The best results were obtained by the combination with the maximum concentration of potassium humate (25 mL L-1) and zinc (20 g L-1), which produced notable changes. The following values were attained: 36.3 leaves, 8.03 panicles, 67.2 flowers, 23.8 fruits, 83.4 g of fruit weight, 84.2 cm of plant height and 1984.9 gm plant-1 for total yield. Based on these results, it is possible to enhance the vegetative growth, flowering and production of tomatoes cultivated in protected environments by utilizing the combination of zinc and potassium humate. Future studies across varieties and environments are recommended to validate these results and assess economic feasibility before large-scale adoption in sustainable fertilization programs.