Effects of foliar sprays of nutrients and plant growth regulators on vegetative growth, fruit yield, quality attributes of Guava (Psidium guajava L.) Cv. L-49

Guava (Psidium guajava L.) is an important tropical and subtropical fruit crop, valued for its nutritional quality and economic importance. However, optimising combinations of foliar application of nutrients and plant growth regulators (PGRs) combinations for improving productivity and fruit quality of mature guava fruit (L-49) under subtropical conditions remains an important production objective. The present study was conducted during the rabi seasons of 2023–24 and 2024–25 at Janta College, Bakewar, Etawah, Uttar Pradesh, India to evaluate the effects of foliar application of urea (1.0 %), potassium sulphate (K₂SO₄) (0.3 %), calcium sulphate (CaSO₄) (0.4 %), gibberellic acid (GA₃) (20 ppm) and naphthalene acetic acid (NAA) (30 ppm), individually and in combinations. The experiment comprised 26 treatments arranged in a randomised block design (RBD) with 3 replications. Among all the treatments, T25 (urea + K₂SO₄ + CaSO₄ + GA₃ + NAA) consistently produced the highest vegetative growth, fruit yield and sugar content and the lowest fruit acidity. At 40 days after spraying, T25 recorded leaf lengths of 12.18 cm and 13.03 cm, leaf widths of 7.15 cm and 7.65 cm, leaf areas of 87.08 cm² and 99.67 cm² and fruit yields of 66.98 kg tree-1 and 68.32 kg tree-1 (186.20 and 189.93 q ha-1) in 2023–24 and 2024–25 respectively. It also recorded the highest total sugar content, with values of 9.58 % and 9.76 % and the lowest titratable acidity of 0.32 % in T25 in both years. The response is likely associated with complementary effects of nitrogen (N) on vegetative development, potassium (K) on photosynthesis and assimilate transport, calcium on cellular integrity and GA₃ and NAA on cell expansion, fruit retention and sink development. Overall, the combined foliar application represented by T25 showed promise as an integrated approach for improving growth, yield and fruit quality of guava cv. L-49 under the agro-climatic conditions of the study area. However, multi-location trials and economic validation are required before wider recommendation.