Growth stages-specific foliar application of boron and 6-benzylaminopurine synergistically improve leaf mineral contents, reproductive attributes, and fruit quality of ‘Chandler’ strawberry

Strawberry cultivation in subtropical regions of Pakistan is constrained by low yield and poor fruit quality, highlighting the need for sustainable agronomic interventions. This two-year field study evaluated the effects of foliar application of boric acid (BA) and the synthetic cytokinin, 6-benzylaminopurine (BAP), individually and in combination, at different growth stages on the vegetative growth, yield, and fruit quality of ‘Chandler’ strawberry. The experiment followed a split-plot design within a Randomized Complete Block Design (RCBD), with application timings—pre-flowering (S1), post-fruit development (S2), and combined (S3)—as main plot, and spray treatment—control (untreated,T1), BA alone (T2), BAP alone (T3), and BA+BAP (T4)—as sub-plots. Results demonstrated that interactive effect S3T4 significantly improved plant vigor, plant leaf count, and flower number across both years as compared to untreated plants. Notably, compared to untreated plants this treatment enhanced yield attributes such as fruit set, number of fruit, average fruit weight, and yield per plant. Fruit quality attributes including color, total soluble solids, titratable acidity, vitamin contents, juice pH, and sensory qualities were also significantly improved. Biochemical fruit analysis revealed higher total phenolics, antioxidants, and activity of antioxidative enzymes. Leaf nutrient analysis showed increased uptake of N, K, and B. However, the combined treatment was associated with lower fruit ripening index and reduced anthocyanin contents. Overall, the strategic foliar application of BA+BAP at critical growth stages presents a promising approach to sustainably enhance strawberry fruit production under subtropical conditions.