Assessment of Systems of Rice Intensification (SRI) Principles on ROK-34 Growth and Yield Under Rainfed Conditions in Moyamba District, Sierra Leone

Climate variability, declining soil fertility, and diminishing effectiveness of conventional agronomic practices increasingly constrain rice (Oryza sativa L.) production in Sierra Leone. The System of Rice Intensification (SRI) is an alternative that is resource-efficient, but empirical evidence on its performance with locally important varieties is lacking. This study assessed ROK 34 growth and yield responses to SRI components, soil amendment, plant spacing, and planting method under rainfed circumstances in Moyamba District, Sierra Leone, during the June-November 2024 growing season. The experiment used a randomized complete block design with four blocks. The treatments consisted of two soil amendments (rice straw compost at 12.5 t ha⁻¹ and no compost), two spacing regimes (15 cm x 15 cm and 25 cm x 25 cm), and three planting methods (direct seeding, 12-day seedlings, and 30-day seedlings). Data were analyzed by Analysis of Variance (ANOVA), correlation analysis, and principal component analysis. The independent and additive effects of compost application, wider spacing (25 cm), and younger seedlings (12 days) on grain yield were observed. In comparison to the average farmer output of 1.5 t ha⁻¹, the optimal combination of amended soil, 25 cm spacing, and 12-day seedlings produced 2.91 t ha⁻¹, representing a 94% increase. ANOVA results showed that grain yield was significantly influenced by soil amendment (β* = -0.243, p < 0.001), plant spacing (β* = -0.277, p < 0.001), and planting method (β* = -0.196, p = 0.018). There was no discernible interactive effect among treatments. Additionally, plant height (β* = -0.190, p = 0.011) and leaf count (β* = -0.237, p = 0.002) were significantly affected by the planting method. Also, correlation analysis revealed an association between grain yield and number of grains (r = 0.99, p < 0.001), effective panicles (r = 0.92, p < 0.001) and 1000-grain weight (r = 0.29). Principal component (PC) analysis explained 83.1% of the total variance. PC1 (54.8%) was dominated by grain yield, number of grains, and effective panicles, and PC2 (28.3%) was dominated by thousand-grain weight. These results prove that the SRI practices can improve the productivity of ROK 34 rice under rainfed conditions. Extension workers should therefore encourage smallholder farmers to gradually shift to soil amendments, increase plant spacing, and transplant younger seedlings to attain better yield stability of ROK 34. Key words: Soil amendment, planting method, local farmers, resources-constrained, rice production