Abstract :
The combination of different concentration of substrate (0.10M, 0.15M, 0.20M and 0.25M, KNO3) with different pH of buffer (0.10 M and 0.20 M, KH2PO4 of the pH 6.5, 7.0, 7.5, 7.6, 7.7, and 7.8) solutions were tried for the nitrate reductase (NR) activity in Albizia chinensis leaf. Maximum nitrate reductase activity was observed in the combination of buffer solution (KH2PO4) 0.10M having pH 7.6 and substrate solution of the concentration 0.15M. Among different individual leaf, NR activity increased up to 6th leaf from top to bottom and then decreased afterwards. Biomass was observed increasing from 1st to 6th and then decreases after seventh leaf. Moisture content was observed between 60 to 70% in 1st to 9th leaf and further decreased from 10th to 12th leaf. It was also found that the nitrate reductase activity increases from 9.00 am till 1.00 pm and thereafter, it starts decreasing till 5.00 pm. In countries like India where soil is nitrogen (N) deficient, restoration of soil fertility is a critical problem. N is the most abundant element on the earth and acquired by plants though fertilizers, mineralization of organic matter and biological nitrogen fixation (BNF). Overuse of fertilizers has lead to surface and ground water pollution. Therefore, BNF is a sustainable method for plants to acquire nitrogen. N fixing trees are widely used in agroforestry and soil improvement in degraded lands. A. chinensis is a multipurpose nitrogen-fixing tree that can be used in various forestry programs for increasing the fertility of soil.
Keyword :
Albizia chinensis; Nitrate reductase (NR) activity; Substrate and buffer solutions.