Effect of genotype, planting density, and NPK levels on seedless cucumber yield, quality, and profitability under protected cultivation

The present study was conducted from 2017 to 2019 at the Vegetable Research Farm, SHUATS, Prayagraj, Allahabad, U.P., with three replications. The experiment included a total of twenty-seven treatment combinations, consisting of three cucumber cultivars: Pant Parthenocarpic Cucumber-2 (V1), Pant Parthenocarpic Cucumber-3 (V2), and Hilton (V3); three plant spacings: 60 × 30 cm (P1), 60 × 40 cm (P2), and 60 × 50 cm (P3); and three NPK fertilizer doses: 20:10:22 kg/1000 m² (D1), 25:15:27 kg/1000 m² (D2), and 30:20:32 kg/1000 m² (D3). Fertilizers were applied twice a week, and the same treatments were maintained across both years. The results indicated that all treatments and their combinations significantly affected growth, yield, fruit quality, and the benefit-cost (B:C) ratio in both years. Among the cultivars, Pant Parthenocarpic Cucumber-3 (V2) was found to be statistically superior, enhancing vine length (2.73 m), stem girth (0.80 cm), leaf area (412.34 cm²), internodal distance (8.38 cm), and reducing the days required for first flower bud initiation (42.14 DAS) and first fruit harvest (55.42 DAS). V2 also produced the highest number of fruits per vine (21.89), minimum unmarketable fruits per plant (1.46), average fruit weight (116.41 g), fruit length (18.35 cm), and fruit width (3.45 cm), ultimately resulting in the maximum yield per vine (2.82 kg/plant) on pooled analysis. Regarding plant spacing, the 60 × 50 cm spacing (P3) was significantly superior for vegetative growth, yield per plant, and fruit quality, except for yield per square meter, which was highest in 60 × 30 cm spacing (P1) and lowest in P3 during both years. Concerning fertilizer application, manual application to the plant root zone (D3) resulted in superior performance compared to lower doses (D1 and D2). Maximum fruits per vine, average fruit weight, yield per vine, and yield per square meter were observed with the highest NPK dose (D3). Furthermore, the highest leaf nutrient content—total nitrogen (3.66%), phosphorus (0.83%), and potassium (2.44%) was recorded under D3, while soil nutrient residues after harvest were lowest with the maximum NPK dose in both years.