Annual Research & Review in Biology

Guava (Psidium guajava L.) is an important horticultural crop in which grafting is widely used to maintain the genetic purity, enhance early growth flowering and fruiting. This study evaluated the effects of four grafting methods such as wedge, side, softwood, and saddle under three propagation environments (open field, mist chamber, and shade net house) during two seasons (October and February) on the physiological and biochemical responses of guava grafts. A Factorial Completely Randomized Design was adopted, and observations were recorded 90 days after grafting. Significant differences (p < 0.05) were observed among grafting methods and environments. Wedge grafting under mist chamber conditions in February consistently produced the highest chlorophyll content (30.34 SPAD), photosynthetic rate (18.58 μmol CO₂m²/s), and nitrate reductase activity (76.58 μg NO₂g/h), indicating superior graft compatibility and metabolic efficiency. Saddle grafting under open conditions recorded the highest phenol content (4.55mg/g), reflecting increased stress and reduced graft success. Antioxidant enzymes such as peroxidase and catalase were also higher in February, suggesting improved lignification and ROS detoxification. Overall, wedge grafting in February under mist chamber conditions suggest most effective for achieving efficacious graft establishment and favourable physiological and biochemical performance in guava.