Role of nano-nutrients in enhancing the growth-regulating potential of paclobutrazol in guava cultivation under agroclimatic conditions of Punjab, India

Guava (Psidium guajava L.), a tropical fruit of nutritional and economic importance, often faces challenges such as excessive vegetative growth, uneven flowering and inefficient nutrient absorption. The present study, conducted in 2023-2024 at the Department of Fruit Science, School of Agriculture, Lovely Professional University, Phagwara, Punjab, evaluated the combined influence of paclobutrazol (PBZ) and nano-nutrients on growth regulation, physiological response, yield and fruit quality in guava cv. Allahabad Safeda. PBZ at 3.0 mL/L, a growth inhibitor was applied in conjunction with nano-boron (0.05 %) to assess their synergistic effects. The integrated application notably curtailed vegetative growth, as reflected by reduced plant height increment (0.45 cm), canopy volume (0.46 m³) and stem girth (0.35 cm), suggesting a reallocation of assimilates toward reproductive development. Enhanced physiological parameters such as chlorophyll content, fruit firmness (5.81 kg/cm²) and specific gravity (1.17) indicated improved plant efficiency. Significant gains were also recorded in fruit weight (187.54 g), length (6.68 cm), diameter (5.65 cm) and yield (26.05 kg/tree). These results highlight the effectiveness of combining PBZ with nano-nutrients in optimizing vegetative control, enhancing fruit quality and boosting yield. This integrated approach presents a sustainable strategy for improving guava production, particularly under resource-limited and variableagro-climatic conditions.