Effect of Nitrogen Sources on Some Physiological Characteristics of Azolla

Abstract

The exterior nitrogen sources seem to have a notable effect on azolla(1,2). At a high concentration, they will inhibit the growth of azolla and nitrogenase activity(2,3). Of these exterior nitrogen sources, Co(NH2)2 Produces the most serious effect, NH4 + — N somewhat less, and NO3 --N the least or no effect al all(4). However, during the cultivation of azolla it is imperative to apply adequate amount of nitrogen fertilizer in order to bring about early budding(l), and as often as not, the ammoniacal nitrogen predominates in the case of paddy soil. This paper aims to look into the effects of various nitrogen sources on growth and nitrogen fixation of azolla, and find out the relationship between Azolla imbricata grown in paddy soil and nitrogen nutritional conditions and effect of various nitrogen sources on growth and nitrogen fixation of azolla, with special emphasis on the function of nitrate nitrogen.