NODULATION STATUS AND NITROGEN FIXING POTENTIAL OF AKASHMONI (Acacia auriculiformis) SEEDLINGS IN TROPICAL MIXED PLANTATIONS

A study was carried out to assess biological nitrogen fixation and observe nodulation status of Acacia auriculiformis (Akashmoni) at mixed plantations in the Seed Research Laboratory and nursery of the Institute of Forestry and Environmental Sciences, Chittagong University (IFESCU), Bangladesh. The plantations consist of one pure planting plot (100% A) and eleven mixed planting plots (1A:1S, 1A:1G, 1A: 1G: 1S, 1A:2S, 1A:2G, 1A:3S, 1A:3G, 2A:1S, 2A:1G, 3A:1S and 3A:1G) of the three common plantation tree species of Bangladesh namely Acacia auriculiformis (A), Swietenia macrophylla (S) and Gmelina arborea (G). In Seed Research Nursery, seedlings of three species were raised in a randomized blocks with three replicates of twelve treatment plots. Nodule number, color, size, shape, form, structure, nodule fresh weight, oven-dry weight and total nitrogen accumulation in the soil of A. auriculiformis seedling were recorded. At the age of 10 month, highest nodulation (143 number) of A. auriculiformis were recorded in the mixed plot (1A:2S) in comparison with pure 100%A plot. Fresh and oven dry weight of roots of the A. auriculiformis seedlings were found significantly (p 0.05) highest in 1A:2S mixed plot. The findings of this study suggest that in comparisons with pure plot, A. auriculiformis fix better nitrogen in mixed plantations.