Response of Apple cv. Super Chief Sandidge to Crop Water Requirement (ETc) Levels and Fertigation under Drip Irrigation: Growth and Yield

The response of apple cv. ‘Super Chief Sandidge’ to different crop water requirement (ETc) levels and fertigation treatments under drip irrigation was investigated during 2023 at SKUAST-K, Shalimar. The experiment was laid out in a randomised complete block design with seven treatments, including a control (T₀), and combinations of irrigation at 100% and 75% ETc and fertigation at 100%, 75% and 50% of the recommended dose of fertiliser (RDF). Treatment T₁ (100% ETc + 100% RDF through fertigation) significantly improved vegetative growth, fruit set and yield attributes. The greatest plant-height increment, trunk-girth increment, trunk cross-sectional area (TCSA) increment and fruit-set percentage were recorded under T₁, at 29.17 cm, 0.52 cm, 0.13 cm² and 57.54%, respectively. The number of days after the reference date for full bloom (DARD) was not significantly affected by the treatments. Fruit length, fruit diameter and fruit weight were also greatest under T₁, at 72.72 mm, 73.85 mm and 180.73 g, respectively. The highest yield (13.14 kg plant⁻¹) and yield efficiency (1.06 kg cm⁻²) were also recorded under T₁. These responses may be associated with optimal soil moisture, efficient nutrient uptake and improved photosynthetic activity. Under the conditions of this study, irrigation at 100% ETc combined with 100% RDF through fertigation was the most favourable treatment for the measured growth and yield parameters in high-density apple orchards.