Influence of potassium on mineral content, yield and quality attributes of dragon fruit (Selenicereus monacanthus) in acidic soil of Eastern tropical region of India

Production of quality fruits has always been the priority for ensuring better nutrition and market value. Considering the role of potassium in fruit quality improvement a study was carried out in dragon fruit under open field condition during 2020 and 2021 in the eastern tropical climatic condition of India. The treatments comprised viz., K-absentia as control (T1), K 50 g hill(-1 )year(-1) (T2), K 100 g hill(-1 )year(-1) (T3), K 200 g hill(-1 )year(-1) (T4), K 300 g hill(-1 )year(-1) (T5), K 400 g hill(-1 )year(-1) (T6) and K 500 g hill(-1 )year(-1) (T7). Application of K @300 g hill(-1 )year(-1) exhibited the maximal acquisition of minerals such as N, P, K, Mg, Fe, Mn, Zn, Cu in shoot and fruit pulp of dragon fruit. However, calcium did not exhibit a discernible trend. However, excessive dose of K (500 g hill(-1)year(-1)) resulted in declination in mineral acquisition. K 300 g hill(-1 )year(-1) (T5) also demonstrated enhanced absolute fruit growth rate, maximal yield, marketable yield, fruit weight, color attributes, bio-chemical attributes such as TSS, carbohydrate, reducing sugar (similar to 20%), protein, citric acid, ascorbic acid content (similar to 2 times). Additionally, the same treatment also manifested an enhancement in biochemical attributes such as betacyanin (similar to 2.2 times), total phenol (similar to 55%), total flavonoid (similar to 2.7 times), alpha-amylase and sucrose synthase activities, and antioxidative property (FRAP activity). Principal component analysis (PCA) illustrated the maximal proximity of most of the variables (quality attributes and mineral nutrient contents) with T5 (K 300 g hill(-1 )year(-1)), exemplifying it as the best representative of all the studied variables.