A COMPARATIVE STUDY OF HYDROPONIC SYSTEMS FOR GROWING PEANUT

Abstract

Hydroponic growing systems have the potential to maximize phytomass production of peanut (Arachis hypogea) for Controlled Ecological Life Support Systems (CELSS). Two greenhouse experiments were conducted with plant nutrients supplied in a modified Evan's solutionusing a nutrient film technique. The objective of this research was to determine the effect of hydroponic growing systems on pod and foliage yield of `New Improved Spanish' and `Georgia Red' peanut. Sub-objectives were to evaluate (i) the impact of channel size and (ii) the impact of gradation in pore size on the separation of the rooting zone from the zone of gynophore development. The treatments consisted in the first experiment of a wide channel (122 by 15 by 46 cm) fitted with a perforated (3.0mm diam.) PVC grid; a narrow channel (122 by 15 by 15 cm) either fitted with a perforated grid or without a grid. For 'New Improved Spanish' peanut dry foliage yield tended to be higher in the wide channel treatment (0.33 kg/sq m). But the narrow channel yielded the highest mean pod dry weight (0.12 kg/sq m). Pore sizes of the screens ranged from infinity (no screen). perforated grid, square mesh. filtering screen (75u) and solid screen (no pores). For `Georgia Red' peanut, the impact of gradation in pore size of screens was variable: pod number was highest with the filtering (food) screen (216/sq m) but pod dry weight was highest for the square mesh treatment (0.09 kg/sq m). Foliage yield was significantly greater for the filtering (food) screen (1.12 kg/sq m) than in any of the other treatments. The findings of the research indicate that use of screens is feasible and will not retard pod development. The presence of a perforated grid tended to result in lower phytomass production for `New Improved Spanish' peanut.