Growth and Mineral Uptake of Moringa oleifera Lam. in Low-Permeability Soils at Different Salinity Levels

Abstract

This study investigated the uptake of minerals by moringa (Moringa oleifera Lam.) and examined the salt tolerance of moringa under different salinity treatments (0, 4, 8, and 16 dS/m). The effect of root growth on soil permeability at different salinity levels was also examined. Moringa showed significant negative effects of salinity on growth parameters at 8 dS/m. Significant growth inhibition was observed for moringa at 16 dS/m. The higher C/F ratios, calculated as (assimilated organ mass)/ (non-assimilated organ mass), in moringa in the 16 dS/m treatment may be due to the inhibition of nitrogen uptake by the roots, causing photosynthesis in the leaves to produce assimilates to sustain the body of the tree. In each moringa organ, the Na concentration increased as salinity increased. Significant differences in concentration were observed for Ca and K in leaves and Fe in stems at different salinity levels. The correlation analysis showed that only Mg and P in the branches and Fe and Mg in the stems were significantly negatively correlated with Na concentration, suggesting that increases in Na concentration cause limited inhibition of mineral uptake by moringa. A significant positive correlation was found between Na and P in the roots. It was suggested that moringa roots may have promoted growth by increasing P uptake in response to increased Na. There was a positive correlation between the length of moringa main roots and saturated hydraulic conductivity. The saturated hydraulic conductivity of the soil without moringa cultivation was 1.1 × 10^-6 cm/s, and moringa root growth increased the saturated hydraulic conductivity by two orders of magnitude (10^-4 cm/s) at 0 and 4 dS/m and by one order of magnitude (10^-5 cm/s) at 8 and 16 dS/m.