Effects of foliar applications of NAA, GA₃, potassium and zinc on leaf and fruit nutrient composition of jujube

In this study, the effects of foliar applications of 2% potassium nitrate (KNO₃), 0.6% zinc sulfate (ZnSO₄), 60 ppm naphthaleneacetic acid (NAA), and 40 ppm gibberellic acid (GA₃) on leaf and fruit nutrient contents of “Demirci Jujube” were investigated during two consecutive years. The experiment was arranged as a randomized complete block design with three replications, each consisting of three trees. Results indicated that leaf and fruit nutrient contents varied significantly across years and treatments. Application of ZnSO₄ resulted in higher K and Mg concentrations in both leaves and fruits, whereas KNO₃ primarily enhanced Ca and Mn concentrations. Among the plant growth regulators, NAA increased leaf K, Ca, and Mn contents, whereas GA₃ increased K, Ca, Mg, and Na levels. Overall, nutrient contents in 2023 were higher than in 2022. The control group generally exhibited the lowest values, while the treatments positively affected leaf and fruit nutrient composition. Principal Component Analysis (PCA) grouped leaf and fruit nutrient data, demonstrating that the treatments influenced physiological relationships among elements; three principal components explained 76% of the variance in leaf data, and four components accounted for 79% of the variance in fruit data. In conclusion, this study shows that foliar applications of K, Zn, and growth regulators improved both leaf and fruit nutrient composition in jujube, exerting integrated effects on mineral uptake and translocation.