EVALUATION OF THE RESPONSES OF EIGHT RICE (Oryza sativa, L.) GENOTYPES TO VARIOUS CONCENTRATIONS OF NaCl IN A CONTROLLED ENVIRONMENT

Abstract

Salinity is an ever increasing problem that reduces rice yield in many rice fields around the world. Developing salt tolerant rice (Oryza sativa L.) genotype is one of the solutions to the problem of salinity. This experiment was carried out in the Department of Crop Science and Horticulture at SUA to assess the salinity tolerance of 8 rice genotypes at the seedling stage. Ion accumulation in plants and dry matter content along with molecular markers were used to evaluate the tolerance of each rice genotype. The genotypes were IRRI 112, IRRI 124, FL 478, IRRI 113, IR65912-4B-10-3, IRRI 128, NERICA-L-19 and SUAKOKO-10. In this experiment, the genotypes were exposed to three salinity levels in a randomized complete block design arranged in factorial with three replications. The salinity levels were 100 mM NaCl, 50 mM NaCl and 0 mM NaCl. The homogenous mixture of sand, farm yard manure and rice husk (ratio of 6:2:10 respectively) was used as the planting medium for all rice genotypes. The soil texture was sandy clay-loam. The growth of the genotypes, ion accumulation and dry matter contents were significantly (p ≤ 0.05) affected by increase in NaCl concentration. Two Saltol SSR markers (RM7075 and RM562) were used to determine the presence of salinity tolerance (saltol) gene in rice genotypes.  Based on the SSR markers, ion accumulation and dry weight of plants, two genotypes (IR65192-4B-10-3, and IRRI112) along with FL478 were selected as salt tolerant while two (IRRI-113 and IRRI-128) were moderately tolerant, and three (NERICA-19, SUAKOKO-10 and IRRI-124) were the most susceptible genotypes.  Therefore, two susceptible parents (NERICA-19 and SUAKOKO-10) were selected and two donor parents (FL478 and IR65192-4B-10-3) were selected.

Keywords: salinity stress; NaCl concentration; genotypes; markers; seedling stage; Oryza sativa;