Rooting Pattern and Yield of Rice (Oryza sativa L.) as Influenced by Soil Water Regimes

Root growth (dry weight and root length density) was highest in the surface (0–0.3 m) layer under continuous ponding (II) and below this depth under submergence two days after the disappearance of ponded water (1₂), Root penetration was shallowest under submerged condition and deepest under rainfed condition. Tall varieties had deeper root system and intermittent submergence gave yield as much as continuous ponding. Grain yield in I₁ was statistically at par with 7.5 cm submergence 2 days after the disappearance of ponded water (I₂), but significantly greater than in 7.5 cm submergence 3 days (I₃) and 5 days (I₄) after the disappearance of ponded water and rainfed condition (I₀). Reduction in grain yield was highest in shallow-rooted varieties and lowest in tall varieties. The regression of relative grain yield on root dry weight and root length density was significant and positive.