P-dipping improved NERICA 4 rice seedling resilience to water and nutrient stresses under rainfed-like conditions

Drought stress and phosphorus (P) deficiency are major abiotic factors that limit the yields of rice in Sub-Saharan Africa. To improve the available P supply in the highly weathered soils in the region, farmers use several P application methods, one of which is P-dipping, i.e., dipping the root of seedlings into P-enriched slurry before transplanting. In this study, a split-plot pot experiment was conducted to determine how the effect of localized P application via P-dipping (using four P fertilizer levels) on NERICA 4 rice growth interacts with two water regimes (waterlogging and moderately dry). Shoot dry weight and plant height differed significantly under the various P-dipping application levels, with an application of 40 kg P ha−1 providing the highest mean values under both water treatments. While the mean leaf area did not statistically differ among the P-dipping treatment levels under the moderately dry condition, all P-dipping treatments had increased leaf area relative to that observed without P-dipping. Mean root length differed significantly between the water treatments, whereas the mean root dry weight was higher with the P-dipping treatments than without P-dipping under both water conditions (36% and 8% mean increases under the waterlogged and moderately dry treatments, respectively). These findings show that P-dipping improves the ability of NERICA 4 rice seedlings to withstand water and nutrient stresses under rainfed lowland at early growth stages.