Influence of Spraying Potassium, Sugar Alcohol, and Boron on Yield and Quality of Melon under Protected Cultivation

Abstract

An experiment was conducted in one of the plastic houses at the Department of Horticulture, College of Agriculture, University of Anbar, during the spring season of 2023. The experiment was designed to investigate the effects of spraying with potassium, a combination of alcohol sugar (Sorbitol), and Boron on the yield and quality of melon under protected cultivation conditions. The study included two factors: the first factor was spraying with potassium at three concentrations: 0, 4, and 8 gm/L, and it was coded as K0, K1, and K2, respectively. The second factor was spraying with a combination of sorbitol and boron at five concentrations that were coded as T0, T1, T2, T3, and T4. Potassium was sprayed when 50% of the flowers appeared and until the fruit ripened at a rate of one spray per week. The combination of Boron and Sorbitol was sprayed on the plants at age of 6-8 true leaves with three times, two weeks interval between sprays. The experiment was conducted as a factorial experiment within a Complete Randomized Block Design with three replicates. The study showed that the second Potassium concentration K1 was superior and achieved the highest (fruit weight, number of fruits per plant, plant yield, and plastic house yield) of 1.238 kg, 3.887 (fruit plant-1), 4.827 (kg plant-1), and 5.793 (tons per house-1). This was compared to the lowest values achieved by the control plants, which were 1.100 kg, 3.533 (fruit plant-1), 3.900 (kg plant-1), and 5.386 (tons per greenhouse-1), respectively. The combination of boron and sorbitol had a significant effect on yield traits, as treatment T4 significantly achieved the highest values in fruit weight, number of fruits, and total greenhouse yield of 1.281 kg, 4.078 (fruit plant-1), 5.232 (kg plant-1) and 6.279 (tons greenhouse-1), compared to the control treatment, which gave the lowest values for the same traits of 1.109 kg, 3.243 (fruit plant-1), 3.604 (kg plant-1), and 4.324 (tons per greenhouse-1). Spraying plants with potassium, especially at level K1, led to a significant increase in fruit quality traits, including fruit pulp thickness, total sugar content, and beta-carotene content, and gave the highest values of 6.550 mm, 10.770 (%), and 10.770 (μg g-1 fresh weight), compared to the lowest values achieved by the control plants, which gave the lowest values of 35.815 mm, 0.7449 (%), and 19.300 (μg g-1 fresh weight) for the same traits, respectively. The combination of sorbitol and boron had a significant effect on fruit quality traits, as treatment T4 plants achieved the highest values for fruit pulp thickness, total sugar content, and beta-carotene content of 48.618 mm, 11.272 %, and 20.754 (μg g-1 fresh weight) compared to the lowest values achieved by the control plants, which were 48.618 mm, 9.434 %, and 19.020 (μg g-1 fresh weight) for the same traits, respectively.