PHYSIOLOGY AND ROOT PROFILES OF DOWNY ROSE MYRTLE (RHODOMYRTUS TOMENTOSA) GROWN WITH PALM KERNEL BIOCHAR UNDER DIFFERENT WATER HOLDING CAPACITY LEVELS

Water stress significantly limits plant physiology, especially in drought-prone locations.Biochar, such as palm kernel (PK) biochar, enhances soil properties and plant resilience during drought.However, its effects on potential soil-stabilizing plants under water deficit are underexplored.Hence, this study examines the physiological responses and root profiles of Rhodomyrtus tomentosa (Downy Rose Myrtle) grown under varying water holding capacities (WHC) (100%, 75%, 50% and 25%) treated with or without 10% (w/w) PK biochar.A six-month shade-house experiment was conducted using a randomized complete block design (RCBD).Biochar-treated plants showed increased photosynthetic rate under water stress, with an increase of 45.27% in plants subjected to 25% WHC.Similarly, improved water use efficiency (WUE) was also observed in biochar-treated plants subjected to 50% and 25% WHC.Root lengths were also significantly increased in biochar-treated plants of 75%, 50% and 25% WHC.Statistical analysis revealed that the interaction between WHC and biochar application significantly affected photosynthetic rate, transpiration rate, WUE and root length, likely attributed to improved soil water availability, nutrient retention contributed by PK biochar, optimizing photosynthesis, gaseous exchange and root development.Overall, PK biochar improved several physiological responses and root profiles of R. tomentosa and may serve as a viable soil amendment for vegetation, such as R. tomentosa in water deficit conditions.