Role of phosphorous and zinc on the growth of Azolla microphylla

Abstract

An experiment entitled “Role of Phosphorous and Zinc on the growth of Azolla microphylla” was undertaken at Plant Pathology Section, College of Agriculture, Nagpur during the year 2024-25. The experiment was conducted in Completely Randomized Design (CRD) with Ten treatments in three replication. Ten micronutrient treatments (K₂HPO₄, HCO₂K, Zn₃(PO₄)₂, ZnCl₂ and their combinations at 0.6 mg/cm³) on Azolla microphylla, with observations at 15, 30, 45, and 60 DAI. Treatment T1 (K₂HPO₄) consistently gave the highest performance across all parameters—fresh weight (1,359.67 g/tank), dry weight, chlorophyll content, heterocyst percentage, frond area, root length, and N/P uptake—followed by T5 (K₂HPO₄ + HCO₂K), which also delivered significantly improved results. Conversely, ZnCl₂ treatments (T3 and T8) suppressed biomass, pointing to zinc toxicity effects. Both T1 and T5 exhibited clear linear growth trends over time, highlighting phosphorus pivotal role in sustaining Azolla productivity. These outcomes are strongly supported by literature: inorganic phosphorus supplementation (10-30 mg L⁻¹) is known to enhance biomass and nutrient accumulation in A. microphylla, while Azolla’s ability to uptake heavy metals like zinc is concentration-dependent and excessive Zn can impair growth