Arbuscular Mycorrhiza Fungi's Effects on Gt 1 Hevea brasiliensis Seedlings' Growth and Physiological Performance in a Drought-Stressed Environment

Drought significantly affects rubber (Hevea brasiliensis Muell. Arg.) cultivation, especially in marginal regions with limited rainfall. This study investigates the potential benefits of arbuscular mycorrhizal fungi (AMF) inoculation on GT 1 rubber seedlings' growth and physiology under drought stress. Topsoil samples were collected and either sterilised or left non-sterilised. AMF inocula were prepared, and GT 1 rubber seedlings were transplanted into bags with different soil types and subjected to watering or drought. Growth parameters and water deficit were measured and analysed. Growth parameters revealed complex interactions between soil type, AMF inoculation, and watering regimes. Well-watered seedlings generally outperformed drought-stressed ones, but certain AMF treatments showed higher stem height. Percentage growth in girth size and height varied among treatments, emphasising the influence of AMF and drought. Leaf area measurements indicated the positive effect of AMF on physiological performance. Results showed the highest girth size at 30 WAT with NS/C/W (0.61 cm). Significant differences in seedling height were observed, with AMF-OP9 in the watered regimen having the highest stem height (62.25 cm at 30 WAT). The highest percentage increase in girth size at 30 WAT was noted in the S/GD/D treatment combination (64.29%). The highest percentage increase in height was in the NS/N4/D treatment combination (20.90 cm at 30 WAT). AMF inoculation enhanced seedling growth, but the response depended on specific conditions. Drought stress negatively impacted growth and water status, with AMF-OP9 demonstrating potential drought tolerance. Water potential and relative water content varied with AMF treatments, soil types, and watering regimes. AMF-OP9 showed promise in improving drought tolerance and water retention. This study highlights AMF's potential to enhance GT 1 rubber seedling growth and physiology in drought-prone regions. Understanding the context-dependent effects of AMF is crucial for optimizing rubber tree cultivation. Further research is needed to elucidate AMF-mediated drought tolerance mechanisms.