Effect of Phosphorus Fertilizer on Morpho-physiological, and Biochemical Traits of Bambara Groundnut (Vigna subterranea (L.) Verdc.) Plants Under Water Deficit

Abstract

Aims: To evaluate the effect of water deficit (WD) and P-fertilizer on the growth and biochemical composition of Bambara groundnut. Study Design: The experimental design was a randomized complete block with three factors: landraces (L1, L2, and L3), single superphosphate doses (0, 20, 40, 60, 100 mg P2O5.kg-1), and watering regime (90% (control), 60%, and 30% of field capacity (FC)). Place and Duration of Study: Department of Plant Biology, Faculty of Science, University of Yaounde I for three months. Methodology: The seedlings (radicle at 2 mm) were sown in the polyethylene pots filled with substrate with the appropriate P-doses. The plants were grown for up to four weeks under normal watering level (90%_FC). Four weeks after sowing (WAS), the WD was applied by stopping irrigation and maintaining the desired FC. At harvest (8WAS), growth, physiological and biochemical parameters were evaluated. Results: P-fertilizer significantly improved growth and biochemical composition under WD or none. The plant height increased from 20.3% from 0 to 100 mg P2O5 at 30%_FC to L2 at the 8th week. At 90%_FC, the doses 20, 40, 60, 100 mg increased sugars content by 52.6, 59.4, 64.6, and 90.4%, respectively, compared to 0 mg at L3. Proline content at 30%_FC was twice (2.5) that of 90%_FC at L2. Increased accumulation of sugars, proline, and amino acids in leaves was recorded at the severe level of WD. Conclusion: P-fertilizer mitigated the adverse effect of WD on the growth and biochemical composition of Bambara groundnut. A sufficient P-supply (60 mg P2O5.kg-1) was recommended to help Bambara groundnut plants tolerate WD. L1 and L3 appear to be more tolerant than L2 and can be recommended to farmers. As the adaptation mechanisms of these landraces to WD are different, it would be advisable to evaluate their performance in the field to better assess their behavior.