Potential of using Chlorella sp. grown in parboiled effluent in combination with organic or inorganic fertilizers: Effects on growth and yield of brinjal (Solanum melongina)

Abstract

Present study was conducted to assess the potential use of Chlorella sp. grown in parboiled effluent as an organic nutrient source. Chlorella sp. was cultivated using parboiled effluent in a raceway reactor for 14 days continuously with constant light intensity (200 µmol photons m-2 s -1) and constant mixing. The algal biomass was washed in distilled water and the nutrient content (N, P, and K) was determined. A pot experiment was conducted to find the response of brinjal (Solanum melongina) for different inorganic or organic fertilizer combinations with Chlorella, balancing the total nitrogen in each treatment except control (T1). The design was CRD with eight treatments and three replicates. The treatments were T1 - Control, T2 - 100% Inorganic Fertilizer (IF), T3 - 100% Cattle Manure (CM), T4 - 30 g Chlorella + 100% Inorganic Fertilizer except N (IFEN), T5 - 15 g Chlorella + 50 % IFEN, T6 - 15 g Chlorella + 50% CM, T7 - 20% Chlorella Foliar Spray (FS)+ 50% IFEN, T8 - 20 % Chlorella FS + 50% CM. Plant height, leaf number, flowers per plant, and the yield of brinjal were recorded and statistically analyzed. The Chlorella had 25% of nitrogen, 7.5% phosphorus, and 0.74% potassium. Significant variations were observed in height, leaf number and flower numbers among different treatments. All the treatments gave either a statistically similar or higher yield than T2 (100% IF), except the control. T6 (Chlorella 15 g + 50% CM) gave a significantly higher yield than all other treatments except T4 (30 g Chlorella + 100% IFEN). Considering the yield, T6 (15 g Chlorella + 50% CM) is the best option in organic combinations while T4 (30 g Chlorella + 100 % IFEN)is the best option in inorganic combinations. This study, therefore, highlights the potential of using Chlorella sp. grown in parboiled effluent as a nitrogen source for crop production. Further studies are required to optimize the nutrient supply including phosphorus.