Effect of different levels of NPK on yield and quality parameters of watermelon (Citrullus lanatus Thunb.)

A field experiment was conducted at the Experimental Orchard, Department of Horticulture, Assam Agricultural University, Jorhat, Assam during 2009–10 to find out the most suitable combination of NPK to produce the highest yield with the best fruit quality of watermelon. The treatments studied were T₁ (50 kg N, 35 P₂O₅ and 50 kg K₂O), T₂ (60 kg N, 40 kg P₂O₅ and 60 kg K₂O), T₃ (70 kg N, 45 kg P₂O₅ and 70 kg K₂O), T₄ (80 kg N, 50 kg P₂O₅ and 80 kg K₂O), T₅ (90 kg N, 55 kg P₂O₅ and 90 kg K₂O), T₆ (100 kg N, 60 kg P₂O₅ and 100 kg K₂O) and a control without fertilizer application (T₇) which were replicated three times. The result of the study revealed that the yield, yield attributing characters and fruit quality of watermelon were significantly affected by the different treatments tested. The highest number of female flowers per vine (14.50), number of fruit per vine (2.43), fruit weight (5.91 kg), fruit yield per vine (14.31 kg), fruit yield per hectare (357.67 q) and the lowest male: female flower ratio (10.49: 10) were recorded in treatment T₅ The same treatment also produced the highest ascorbic acid content (5.14 mg/100 g). However, the highest fresh and dry weight of the vine (3.56 kg and 9493.52 g) respectively and TSS (9.30%) were observed in case of T₆ which was at par with T₅. The 90 kg N, 55 kg P₂O₅ and 90 kg K₂O/ha (T₅) could be suggested as the best fertilizer treatment combination for watermelon in agro-climatic condition of Assam which also maintained the highest benefit: cost ratio of 5.47: 1.