Physiological Response of Hibiscus Sabdariffa to Multi-Year Rainfall-Leached Allelochemicals of Tithonia Diversifolia and Chromolaena Odorata

Abstract

The awareness of conditions under which fallowed land stimulate the general growth and yield of subsequent crops would enable us to effectively manage the land and take advantage of the growth-enhancing potential of the leachates of fallowed weeds. A four-year experiment was conducted under natural condition to explore and compare the effects of one, two and three year's accumulated leachates plus exudates of Chromolaena odorata or Tithonia diversifolia on the growth, calyx yield, accumulation of chlorophyll, ascorbic acid and protein in Hibiscus sabdariffa crop. Seedlings of H. sabdariffa were grown on the soil which had received one, two and three year's aqueous-leachate plus exudates of C. odorata or T. diversifolia. Results show that all the studied parameters were enhanced by the leachates plus exudates of both weeds in individual year. However, optimum enhancement of these parameters was induced by two years accumulated leachates plus exudates while the three years accumulated leachates plus exudates induced least enhancement. Generally, the study presents the leachates plus root exudates of these weeds as a good source of cheap and highly effective crop-growth enhancer. It also recommends the accumulated two years leachates plus exudates or a piece of land dominated with these weeds and fallowed for two years for enhancing and optimizing the production of H. sabdariffa. Accumulation of ascorbic acid could be the adaptive mechanisms evolved by H. sabdariffa to allelopathic tolerance. Screening for the active ingredients in these weeds leachates and/or exudates is therefore suggested so as to produce crop-growth enhancer or regulators.