Effect of Phosphorus Levels on Early Seedlings of Rice (Oryza sativa) under Varying Moisture Stress Conditions

This study investigated the impact of moisture levels and phosphorus applications on different rice varieties. It aimed to: 1. Identify optimal rice varieties for specific moisture and phosphorus combinations. 2. Understand how moisture stress affects seed germination speed and root and shoot development. 3. Analyze the influence of increased phosphorus on root growth, especially under moisture stress. 4. Evaluate if additional NPK application enhances the positive effects of phosphorus.

The meticulously controlled experiment, conducted within the International Rice Research Institute (IRRI)'s RGA facility from October to November 2023, utilized five rice varieties, three moisture levels (flooded, ideal, and Drought-like), and varying phosphorus levels.

The findings revealed a positive correlation between phosphorus levels and root length across all rice varieties. This emphasizes the crucial role of phosphorus in promoting root development under challenging conditions. Notably, while increased phosphorus significantly enhanced root adhesion under flooding and aided seedling recovery, drought remained a significant barrier to root growth, regardless of phosphorus application. Interestingly, despite general genetic uniformity in germination and root-shoot parameters among the varieties, a clear positive correlation between phosphorus levels and root length was still observed.

In conclusion, this study highlights the importance of phosphorus in strengthening root grip during floods, thereby aiding seedling recovery. However, it also emphasizes that drought remains a dominant factor hindering plant growth. The consistency observed across different rice varieties strengthens the findings, and the significant increase in root length with increased phosphorus application underscores its vital role in root development under challenging conditions. This study provides valuable insights for optimizing rice growth strategies by considering specific rice varieties, moisture levels, and phosphorus applications.