The Effect of Residual Potassium (K) and Poultry Manure (PM) on the Root Distribution of Two Cultivars of Taro Grown on Tokotoko Soil Series in Fiji

摘要

The root growth and development pattern of the two cultivars of taro used in this experiment varied in terms of root distribution, root weight, root number and root length. Vula Ono gave significantly heavier roots (0.21 g per plant) compared with Tausala-ni-Samoa (0.15 g per plant). The addition of poultry manure (10 t ha-1) significantly increased root weight, 0.22 g per plant compared with 0.14 g per plant for treatments receiving no poultry manure. Potassium (K) and PM significantly affected root numbers. Plots with K at 150 kg ha-1 produced 29 roots per plant and those with K at 300 kg ha-1 gave significantly more roots at 36 roots per plant. Similarly, plots with no PM produced 29 roots per plant and those with 10 t ha-1 gave 37 roots. There was a highly significantly cultivar x poultry manure interaction caused by an increase in root numbers with addition of poultry manure in the cv. Vula Ono but no change in the cv Tausala-ni-Samoa. Potassium (K) and Poultry Manure (PM) significantly affected root length when separately applied. Plots with higher rates of K (300 kg ha-1) had significantly longer roots than those with low rates (150 kg ha-1). Similarly, plots with PM had taro with longer roots than those without PM. There was a highly significant cultivar x poultry manure interaction on root length caused by an increase in cv. Vula Ono root length with addition of poultry manure but no effect on the root length of Tausala-ni-Samoa. There was a significant decrease in root weight, number and length with depth for Tausala-ni-Samoa but these were nearly the same for Vula Ono for depths of 0.1, 0.2 and smaller for the depth of 0.3 m. This showed that roots of cv. Vula Ono were more evenly distributed in the soil profile and maybe more efficient in using below ground resources including those applied to the soil. Poultry manure improved root penetration since there was a highly significant difference in root weight, root numbers and root length with depth.