Enhancing productivity of kinnow mandarin orchard through fertigation under low hill zone of Himachal Pradesh, India

Field investigations were undertaken during the period 2018-2019 to find out the effect of different fertigation levels on growth, yield and quality of kinnow mandarin. The field experiment was laid out in completely randomized block design with five treatments (100% recommended dose of fertilizers (RDF) direct application to soil (control: T₁), and four fertigation levels, viz. 125% (T₂) 100% (T₃), 75% (T₄), and 50% (T₅) of RDF) replicated six times. The findings revealed that among all the treatments, the highest trunk girth (0.60 m), tree height (3.50 m), tree spread in east-west (3.80 m) and north-south (3.67 m) directions and canopy volume (24.70 m³) was recorded in treatment T₂ (125% RDF) followed by treatments T₃,T₄, and T₅, which were superior over the control (T₁). The maximum fruit weight (194.2 g) in treatment T₂ was found to be statistically at par with that recorded in treatment T₃. Similarly, the minimum fruit weight (168.5 g) recorded in treatment T₅ (50% RDF) was found to be statistically at par with that recorded in control treatment T₁ (174.9 g) with 100% RDF as soil application. The highest fruit yield (40.98 kg tree^-1 and 13.65 t ha^-1) was recorded in treatment T₂ followed by 100% fertigation (38.83 kg tree^-1) and was found to be at par with treatment T₄ (75% fertigation). Significant effects of the fertigation were noticed in fruit quality parameters, i.e., acidity and total soluble solidsacidity ratio, juice content and vitamin C except for total soluble solids, which increased significantly as compared to soil application of 100% RDF. The findings suggested that treatment T₄ (75% RDF) as the most economically efficient treatment, with a cost of Rs. 160,868 and the highest benefit-cost ratio of 1.92, providing substantial net returns of Rs. 308,292 while saving 25% fertilizer usage.