Analysis of components traits and mechanisms associated with drought stress tolerance in clonal and seedling trees of Pongamia pinnata (L.) Pierre

A study was conducted with clonal and seedling-derived trees of Pongamia pinnata in the field conditions at the ICAR-Central Agroforestry Research Institute, Jhansi, India, with an objective to unravel the mechanistic insights for drought stress tolerance in clonal and seedling trees of Pongamia pinnata through comparative physio-biochemical determinants. Photosynthetic CO₂ assimilation (P_Nmax) and its associated parameters, along with chlorophyll fluorescence traits were analysed. Leaf water potential (LWP) was measured with the PSΨPRO water potential system. Findings of the study showed that clonal plants performed better than seedling plants during dry heat summer (DHS) by maintaining higher P_Nmax and its associated traits and P_Nmax was supported by a higher LWP. Additionally, elevated peroxidase (POD) activity and diminished malondialdehyde (MDA) levels in clonal plants as compared to seedling plants during DHS were validated by photosynthetic and chlorophyll fluorescence traits, thereby affirming their superior performance. In addition, clonal plants also recorded higher plant height, diameter at breast height (DBH) and 100-seed weight, signifying their higher resilience during DHS. Principal component analysis (PCA) unveiled that LWP, P_Nmax and Gs were major contributors to total variance. The study inferred that clonal plants of Pongamia pinnata maintained relatively higher physiological functioning during DHS.