Screening of Rice ( Oryza sativa L.) Genotypes for Salinity Tolerance in Ethiopia

Abstract

This study was carried out to investigate the effect of 4 different salinity levels (0, 4, 8 and 12 dSm-1) on yield of 13 rice genotypes along with a salt-tolerant and susceptible check genotypes to identify salt tolerant rice genotype to be used under irrigation. A factorial combination of the fifteen genotypes and four salinity levels was laid out in completely randomized design (CRD) in two replications in a mesh house. The experiments were conducted at Werer Agricultural research Center, eastern Ethiopia, from December, 2008 to May, 2009. Since all plants of all genotypes died under salinity level of 12 dSm-1, grain yield data obtained from three salinity levels are included in the analysis. Statistical Analysis of Variance (ANOVA) revealed highly significant difference among the test genotypes in all traits studied, witnessing the availability of ample genetic variability which can be used in breeding rice for tolerance to salinity. Salinity levels affected all measured traits. The Genotype x Salinity interaction was also significant for all traits except for Plant Height during Heading, Panicle Length, Number of Panicle, Number of Grains per panicle and Number of Tillers per plant, indicating the inconsistency of the performance of genotypes by many of the traits over the salinity levels and the need for selection of rice genotypes specifically adapted to a particular salinity level. In the pot experiment an increase in salinity from 0 to 4 and to 8 dSm-1 consistently reduced growth parameters, biomass, grain yield and its components, but delayed phenology. Genotypes IR66946-3R-176-1-1 (G15) and IR68144-2B-2-2-3-2 (G8) were tolerant to salinity both during early growth and later during vegetative growth, and seed setting. IR59418-7B-21-3 (G1), IR59418-7B-27-3 (G2) and IR72593-B-18-2-2-2 (G13) were found to be salt tolerant during vegetative growth and seed setting. These five genotypes can therefore be recommended for further testing under salt stress. Higher grain yield and its components under salt stress and smaller reduction of these parameters under salt stress as compared with values under normal growth condition should be used as selection criteria to develop salt tolerant rice genotypes. AMMI biplot analysis enabled clear discrimination of genotypes response against root zone salinity stress.