Morphological Adaptation of Vernonia Amygdalina in a Cadmium-Spiked Soil Influenced by Periodic Soil Wetting with Grey Water

Abstract

The study investigated morphological changes in Vernonia amygdalina in a cadmium-spiked soil influenced by periodic soil wetting with grey water. Soil was spiked with cadmium (as cadmium chloride) to obtain a constant concentration of 150 mg/kg. The set up was divided into six sub-treatments of nine replicates each. Each sub-treatment was subjected to periodic wetting with grey water (at 50ml/kg), ranging from daily (D), twice a week (DW), once a week (W), twice a month (WM) and once a month (M). The control soil on the other hand, received regular wetting with tap water (pH 6.46 – 7.02). Subsequently, equal-sized stem cuttings of Vernonia amygdalina (20 cm long, 2.5 – 3.0 cm thick) obtained for the study were sown in both treated and control soils. Results obtained at 21 weeks after sowing showed that treated plants had the highest total number of leaves per plant (between 76 and 105), compared to the control (51 leaves). There was also significant leaf chlorosis in the control leaves (60.60%) than in the greywater-wetted plant treatments. No necrotic lesions were observed in any part of the leaves for both control and treated plants. There was significant (p < 0.05) change in dry weight of plant shoots, with the daily (D) treated plants weighing more (25.53g) than other treatments (11.56 to 17.25g). However, there were no significant changes in plant root dry weight (1.03 to 3.58g) for all the treatments