Upland Rice Genotype Evaluations for Acidity Tolerance

Upland rice is an important crop in South American cropping systems. In Brazil it is mainly grown in the central area, locally known as the Cerrado region. Soils of the Cerrado region are acidic and have poor fertility. A greenhouse experiment was conducted with the objective to evaluate thirty upland rice genotypes for acidity tolerance. Two acidity levels were created: high (without lime addition) and low (addition of 2.5g dolomitic lime per kg soil). Plant height, straw yield, grain yield, panicle number, thousand-grain weight, spikelet sterility, grain harvest index (GHI), maximum root length, and root dry weight were significantly influenced by lime and genotype treatments. Limexgenotype interactions were also significant for most of these traits, indicating variation in these treats with the variation in acidity levels. Based on grain yield acidity tolerance index (GYATI), genotypes were classified as tolerant, moderately tolerant, and susceptible to soil acidity. Among thirty genotypes, 30 percent were classified as tolerant, 53 percent were classified as moderately tolerant, and 17 percent were classified as susceptible to soil acidity. Most of the growth, yield, and yield components had significant quadratic positive association with grain yield across two acidity levels. Soil acidity indices such as pH, base saturation, calcium (Ca) saturation, magnesium (Mg) saturation, and potassium (K) saturation increased with the addition of lime. Phosphorus content also increased with the addition of lime. However, hydrogen and aluminum (H+Al) and iron (Fe) content decreased with the addition of lime. Adequate soil acidity indices for grain yield were established.