Influence of Paclobutrazol and Potassium Nitrate on Vegetative Growth, Leaf Nutrient Status, Flowering and Yield of Mango (Mangifera indica L.) cv. Amrapali Planted under Different Spacing

The flowering and fruiting of individual mango plant under high density planting is comparatively low. Among different strategies evolved, paclobutrazol and potassium nitrate application is effective not only in flower induction but also in early and offseason flower production in mango. A field experiment was conducted to study the effect of paclobutrazol and potassium nitrate on the vegetative growth, nutrient mobilisation to leaves, flowering and fruit yield of Amrapali mango (Mangifera indica L.) plants grown under different plant spacings at Horticultural Research Station, OUAT, Bhubaneswar during 2018-19 and 2019-20. The experiment was laid out in a Factorial Randomized Block Design with 24 treatment combinations and 2 replications. The treatment combinations consist of four levels of spacings (2.0 x 2.0 m, 4.0 x 2.0 m, 4.0 x 4.0 m, 8.0 x 2.0 m) and 6 levels of chemical treatments (Paclobutrazol@0.25, 0.50 and 0.75 g a.i. per meter of canopy spread and KNO3@ 2% and 4%) and a control with water application. The results of the study revealed that the plants spaced at 2.0 x 2.0 m recorded minimum vegetative growth except plant height and maximum yield (t/ha) in comparison to the plant spacing of 4.0 x 2.0 m, 4.0 x 4.0 m, 8.0 x 2.0 m. Among chemical treatments paclobutrazol irrespective of its concentration significantly reduced vegetative growth, increase flowering intensity and yield. There was a reduction in leaf N, P and K contents and increase in total leaf chlorophyll content in the plants treated with Paclobutrazol. Higher concentration of Paclobutrazol (0.75 g a.i.) reduced the yield. Whereas KNO3 increase the vegetative growth, leaf biochemical status, flowering intensity and yield. But the increase in yield of mango plant due to Paclobutrazol treatment @ 0.50 g a.i. and 0.25 g a.i. was significantly higher than KNO3 at both the applied concentration. Hence, soil drenching of paclobutrazol at 0.50 g a.i. per meter of canopy spread irrespective of plant spacing during September seems recommendable for regulating tree size and enhancing yield in mango cv. Amrapali planted under higher densities. The productivity of Amrapali mango plant can be improved through application of flower inducer like PBZ and KNO3.