Comparative Study on the Effect of Organic and Inorganic Fertilization on the Vegetative Growth of Three Hibiscus Species

Given the rising demand for the species of the genus Hibiscus, namely, Hibiscus rosa-sinensis (Chinese Hibiscus / Rama), Abelmoschus esculentus (Okra / Okro) and Hibiscus sabdariffa (Zobo / Roselle) in ornamental, medicinal, nutritional and industrial sectors, there is a need of evidence-based fertilization strategies that sustain both productivity and ecology. The effect of these two fertilization methods (organic and inorganic) was compared with the effect of an unfertilized control on vegetative growth of three Malvaceae-family crops. Experimental research design was adopted, and the research was carried out at the Federal University of Education (FUE) Zaria Biological Garden for six weeks during the early vegetative growth period under controlled field conditions. Three treatment groups were used for each species, with key parameters measured being plant height, leaf size, leaf number, leaf colouration (as an indicator of chlorophyll content), stem girth and plant vigour. The result showed that the organic fertilization always had positive effect on leaf size, leaf greenness and plant height of three species, namely Hibiscus rosa-sinensis (Chinese Hibiscus / Rama), Hibiscus sabdariffa and Abelmoschus esculentus, although the significant difference occurred only in Hibiscus rosa-sinensis (Chinese Hibiscus / Rama), followed by Hibiscus sabdariffa and the moderate difference was found in Abelmoschus esculentus. Inorganic fertilizer was moderately beneficial compared to the control, but was always less than organic inputs in all measured parameters. The results confirm the positive effect of organic fertilization on vegetative development, due to higher soil microbial activity, nutrient cycling and soil moisture availability. The study suggests that the use of organic fertilizers preferably in combination with a very small amount of inorganic fertilizer is a sustainable and effective practice for the production of Hibiscus species and allied crops in Nigeria.