Effects of seedling source variation on nitrogen metabolism and biomass production in Albizia lebbek

Seedlings of Albizia lebbek were collected from five different Forest Department nurseries, namely, the forest divisions from Barkot and Lalpani in Dehra Dun; Kalsi in Chakrata; Kiratpur Sahib in Roopnagar (Punjab); and Lalkuan in Haldwani to study the changes in some growth parameters, mineral nutrients (nitrogen, phosphorous and potassium) in different parts of the seedlings and in-vivo nitrate reductase and nitrogenase activity. Overall highest and lowest growth, biomass production and nitrogenase activity were recorded in Barkot and Kalsi sources respectively. The reverse trend was observed for the number of nodules per plant and nitrate reductase activity. The highest and the lowest contents of nitrogen and phosphorous in leaves and stem were recorded in Kalsi and Kiratpur Sahib seedlings respectively. Barkot source exhibited the highest contents of total nitrogen and total phosphorous per seedling whereas total potassium content per seedling was highest in seedlings from Kiratpur Sahib. The physiological changes in the seedling behaviour may be attributed to the variation in the origin of seed and the prevailing edaphic conditions, including rhizospheric microflora.