Micronutrients and the activity of nitrogenase in azolla

• Main Authors: Wei You zhong, Yang Yu ai, Sun Xi
• Format: Conference Proceeding
• Language: English
• Published: 1987
• Subjects: azolla; china; chine; fijacion del nitrogeno; fixation de l' azote; nitrogen fixation; nutrientes; nutrients; substance nutritive

The materials used in this experiment were Azolla imbricata, A. japonica, A. filiculoides (E.G.), and A. filiculoides (ph). Plant samples were incubated in a nutrient solution of demineralized water containing known amounts of nutrients. After incubation, the plants were analyzed for N, P, Si, Ca, Mo, Mn, Fe, Cu, Zn, Co, and P. Azolla had higher concentration of these elements than the nutrient solution, demonstrating that azolla has the ability to concentrate these elements from solution. Nitrogenase activity was measured by the acetylene reduction method. The series of activities were A. japonica, A. filiculoides (E.G.), A. filiculoides (ph), A. mexicana, and A. imbricata. The correlation between nitrogenase activity (x) and Mo (Y1) of all the azolla samples tested is at the 1% level of significance, while Cu (Y2) is at the 5% level of significance. Under experimental conditions the regression equations are: Y1 = -2.71 + 2.43 X; Y2 = 0.529 + 0.294 X. The rate of growth and N2 fixation capacity of azolla have been calculated. The series of the rate of growth is A. filiculoides (ph) > A. filiculoides (E.G.) > A. japonica > A. imbricata. Nitrogen-fixing capacity in order is A. japonica > A. filiculoides (E.G.) > A. filiculoides (ph) > A. imbricata. In nutrient concentrations, nitrogenase activity, rate of growth, and N2-fixing capacity, A. japonica and A. filiculoides (E.G.) are superior. A. filiculoides (E.G.) was taken as an example for calculating the correlations among the essential nutrients. N and Mo, N and Fe, and Ca and Co correlated positively. The correlations between P and Cu and between P and S were negative. Cu and Mo, Fe and Mo, P and Zn, Ca and B, and N and Cu had higher correlations. The results indicate that nutrient solution and fertilization affect the performance of azolla.