Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, U.P., 221 005.
In a solution culture experiment, effect of three levels of phosphorus and zinc on fresh biomass, N content and number of heterocyst cm−1 were studied at 10, 20 and 30 days growth of Azolla caraliniana (Wild) during kharifand rabi seasons. Significantly more biomass and N content in Azolla was caused by 7 mg P kg−1. At early growth stages, average increment in the fresh biomass was more during kharif than in rabi but more content of N in fern Agalla was recorded during rabi. Application of 14 mg P kg−1 appeared to be detrimental because it significantTy decreased fresh biomass and N content of Azalla. Response of 0.1 mg Zn kg−1 application was more than 0.05 mg Zn kg−1 Seasonal variation did not influence much the number of heterocyst cm−1 Content of N and average number of heterocyst cm−1 decreased with advancement of time. Simultaneous application of P and Zn was the best treatment combination.
Azolla, season, heterocyst, inoculation, phosphorus and zinc
