RESPONSE OF ROSELLE PLANTS (Hibiscus Sabdariffa, L.) TO CHEMICAL AND BIO-FERTILIZERS.

Abstract

This study was carried out in two field experiments during the two successive seasons of 2006 and 2007 to investigate the effect mixture of biofertilizers (namely, Rhizobium leguminosarum and Azotobacter chroococcum ) either alone or in combination with chemical fertilizers (NPK at the rates of 50 ,75 and 100% of the recommended by Ministry of Agriculture, Egypt ) on growth, yield and chemical constituents of roselle plants. The obtained results indicated that, inoculation of roselle seeds with Rhizobium and Azotobacter alone significantly decreased vegetative growth (i.e. plant height, number of branches, number of leaves, leaf area and dry weight of leaves) and yield (i.e. number of flowers, fresh and dry weights of sepals/plant and per Fadden). Also, chemical constituents (i.e. N, P, K, chlorophyll a, b, carotenoids, anthocyanin, total carbohydrates, and acidity) were increased as compared to control plants during the two successive seasons. On the other side, the treatment 50 % NPK in combination with mixture of biofertilizers gave a slight decrease in the previous plant characters. On contrary, a significant increase of the above plant characters was obtained by the treatment with 75 and 100 % NPK in combination with mixture of biofertilizers as compared with the control plants. The difference between the treatments 50 or 75 % NPK in combination with mixture of biofertilizers and 100% NPK alone (control plants) were slight. So, it is recommended to use biofertilizers in combination with chemical fertilizer (especially, 50 or 75 % NPK) to obtain a safety agricultural products for human health and the environment,