Control of Blossom End Rot Disorder and Improvement of Chemical Composition and Yield of Watermelon by Using Organic Matter, Potassium, and Calcium in Light Soils Irrigated with Semi-Saline Water

Iran is one of the most important watermelon producing countries and globally ranks the second in terms of watermelon cultivated area. Kerman Province is in the southeast of Iran and ranks the first watermelon producing province in the country. However, in the last decade, drought, physical and chemical properties of soil, poor quality irrigation water, lack of proper and balanced nutrients have caused outbreak of blossom-end rot, leading to quantitative and qualitative losses in watermelon. Therefore, effects of simultaneous application of organic matter, potassium, and calcium on yield, chemical composition, and blossom-end rot of watermelon were investigated. The studied variables included organic matter (0 and 20 ton/ha of animal manure), potassium sulfate (0, 250. and 350 kg/ha) and calcium chelate foliar application (0 and 4 g/L). The project was conducted in Randomized Complete Block Design in Faryab in southeast of Iran. The irrigation water salinity was 2100 µs/cm. Results revealed that organic matter application and foliar calcium chelate caused increase in yield, calcium, iron and zinc concentration in the plant, and decrease in blossom-end rot of watermelon fruit significantly. Moreover, potassium sulfate led to yield increase, but its application more than 250 kg/ha caused concentration reduction in calcium, iron, and zinc in plant and increase in blossom-end rot.