Species Specific Responses to Age on Nodule Formation, Seedling Growth, and Biomass Production of Acacia auriculiformis at Nursery Stage

Nodulation responses of leguminous trees are very important for intercropping to reduce reliance on artificial nitrogen input through nitrogen fixation in agroforestry system. This study was carried out to evaluate the status of nodulation (i.e., the number of nodules and their shape and size) in root and biomass production of plant growth parameters (i.e., number of leaves, shoot height, root biomass, and shoot biomass) of A. auriculiformis seedlings. The assessment was conducted 60 days after seed germination. The study revealed significant differences in nodule number per seedling, leaf number per seedling, shoot height, and biomass accumulation (both green and oven dry weight) with seedling age (p<0.05). The study also revealed significant correlation among the variables of nodulation responses and biomass production. The results obtained using principal component analysis (PCA) justified correlation matrix of nodulation responses and biomass production of this species. The PCA showed that root biomass per seedling, leaf number per seedling, nodule number per seedling, shoot height, age of seedling, and shoot biomass per seedling were clustered with PC1 (with an eigenvalue of 5.59) and root shoot ratios were clustered with PC2 (with an eigenvalue of 1.82). Our study justified that shoot height may be an important determinant of nodule formation of A. auriculiformis