Effect of phosphate deficiency on growth and phosphorus content of three Voandzou (Vigna subterranea (L.)Verdc.)varieties

The aim of this study was to investigate the effect of phosphate (Pi) deficiency on growth and phosphorus content of three varieties (V1: white, V2: red and V3: burgundy/purple) of Bambara groundnut (Vigna subterranea (L.) Verdc.). For this purpose, plants were grown for 30 days in a greenhouse on river sand, watered with Hoagland solutions of two different concentrations of Pi (0 and 1000 μM Pi). The results obtained showed that from 1000 to 0 μM Pi, V. subterranea shoot fresh biomass reduced by 13.48%, 9.46% and 14.57% for varieties V1, V2 and V3 respectively. Its total fresh biomass also reduced by 8.29% for V1, 3.32% for V2 and 6.94% for V3. But Pi deficiency (0 μM Pi) led to an increase in root fresh biomass (V2: 8.82% and V3: 7.90%) and root/shoot ratio (V1: 15.17%, V2: 21.57% and V3: 25%). These results show a preferential allocation of biomass to the roots in Pi deficient plants. Pi deficiency had no significant effect on the number of emerged leaves and the plant water content of V. subterranea. However, it increased the specific leaf weight (0.027 for 0 μM Pi and 0.023 g.cm -2 for 1000 μM Pi in V1). The total leaves and roots phosphorus content of Pi deficient plants (0 μM Pi) significantly decreased compared to non-deficient plants (1000 μM Pi). The Pi deficient plants showed better efficiency in phosphorus assimilation. V1 had the best vegetative growth, V2 showed highest phosphorus use efficiency and V3 contained more phosphorus in its organs.