Performance of Rice Genotypes in Non Sodic and Slightly-Saline Soils within Taita Taveta County

Abstract

Background: A member of the Poaceae family, rice is utilised both for grain consumption and as forage or biomass for energy. It is one of the world’s most important cereal crops, serving as a staple food for over half of the global population. Aims: Identify high-yielding, stress-tolerant rice varieties suited to slightly saline and non-sodic soils in Taita Taveta County, and develop site-specific varieties and optimum Nitrogen dose to improve rice productivity and reduce reliance on rice imports. Methodology: A split-plot Randomised Complete Block Design with three replications, tested five rice varieties as the main factor, and seven nitrogen doses as sub-factor, with blocks and plots separated by 2m and 1m wide pathway, respectively. Each subplot measured 5m2 and they were separated by Polythene barriers to prevent nutrient leaching between subplots. Five rice varieties (NERICA 1, CSR 36, KOMBOKA, 17KH090014B, and AT058) were assigned randomly to main plots, while seven nitrogen rates (0-control, 17, 34, 51, 64.5, 83.4, 101 kg N ha⁻¹) formed the subplot treatments. Leaf length, leaf width, and number of leaves were measured at 45 days after transplanting (DAT) from five randomly selected plants per plot, excluding border rows and the central 1 m² area (8), while grain yield, 1000grain weight and dry biomass weight were determined from the middle 1 m² at crop maturity stage. Results: Soil type, genotype, and season significantly (p ≤ 0.05) affected dry biomass, grain yield, 1000-grain weight, leaf area index (LAI), and harvest index. Non- sodic soils supported higher yields for most varieties, with NERICA 1 (1.76 t ha⁻¹) and 17KH090014B (1.35 t ha⁻¹) outperforming others, while AT058 consistently yielded the lowest. On slightly saline soils, 17KH090014B (1.50 t ha⁻¹) and KOMBOKA (1.20 t ha⁻¹) achieved the highest yields. Across soil types, 17KH090014B recorded the greatest biomass (10.21 t ha⁻¹), 1000-grain weight (24.16 g), and grain yield (1.43 t ha⁻¹). Higher yields in NERICA 1 and 17KH090014B were linked to greater LAI and heavier grain weight. 17KH090014B was the most stable variety, especially during the long rains. Conclusion: Among the five upland rice varieties used in this study, NERICA1 and 17KH090014B attained higher yields in non-sodic soils, attributed to higher LAI and heavier grain weight. Nonetheless, further research to validate these findings across other regions and seasons, and to develop location-specific recommendations that support national rice development goals, is critical.