Growing Peanut In Bioreacto'R Effluent

Peanut (Arachis hypogea cv. 'Georgia Red') plants were grown, for periods of up to 109 days, in hydroponic culture, using ratios of modified (N:K = 1:2.4) Hoagland solution amended with the filtered effluent from aerobic bioreactors. The percentages of effluent used with the basal crop nutrient of modified half Hoagland (MHH) ranged from 0 to 100%. The source of effluent used in the studies were bioreactors from laboratory scale testing of aerobic biodégradation of inedible plant biomass. Experiments were conducted in Environmental Growth Chambers (EGC) with an average chamber volume of 2.1 m"3 and a day/night cycle of 12 h at 28°C and 12 h at 22°C. The average daily photon flux for the experiments reported was 600 μιηοΙ.πι"2^"1. The plants were grown at ambient CO2. Incorporating the effluent at ratios of 60% and higher were non-deleterious for peanut foliar growth. But increasing the effluent content caused a decline in the mean dry biomass per plant, with values for the MHH plants of 4.83±0.01 and of 2.1H0.15 and I.90±0.42 g/ plant, for the plants grown in 80% and 100% effluent, respectively. Also, the calcium content of effluent treated plants was significantly (P<0.05) reduced, when compared with control plants. The challenge facing researchers is the attainment of a balance between the maximum amount of effluent that may be utilized to provide nutrients for crop growth while not inducing a phytotoxic response.