Effect of Compost on Agro-Botanical Components Responsible for Rice (Oryza sativa)Grain Yield in Southwestern Nigeria

Abstract: Rice ranks first among cereal food crops with direct human consumption. The production trend is at a far distant behind its demand especially in West Africa sub-region. In spite of dissemination and adoption of diverse improved rice varieties the impact on increase in grain yield on nutrient limiting soil is marginal. Therefore this study was conducted to examine morphological traits that has direct link with sink capacity. The study was conducted over two seasons each in a typical derived savannah and humid rain forest agro-ecologies. The trial was a split plot design laid out in a randomized complete block with three replicates. The main plots were three upland rice cultivars (Ofada, NERICA 1 and NERICA 2) while the sub-plots were four compost rates (0, 4, 8 and 12 t ha^-1) and 90kg ha^-1 NPK (20-10-10) fertilizer. NERICA 1 had the highest grain yield (5.57t ha^-1) in plots fertilized with NPK but not significantly (p> 0.05) different from yield obtained in NERICA 2 (4.95t ha^-1)and Ofada (4.52t ha^-1) plots augmented with 8t ha^-1 compost in derived savannah. Similarly in humid rainforest, NERICA 2 had the highest grain yield (7.40t ha^-1) on NPK fertilized plots but not significantly different from NERICA 1 and 2 cultivars (5.31 and 5.55t ha^-1) augmented with 4t ha^-1 or Ofada (5.90t ha^-1) augmented with 8 t ha^-1compost. Number of leaves, plant height and leaf area were significantly associated with grain yield. Three morphological and five sink capacity characters contributed 92% to total grain yield (tha^-1). Residual effect of compost had no significant (p> 0.05) effect in improving growth or grain yield of upland rice on soil with marginal nutrient.