Exploring Salinity Tolerance in Advanced Rice Lines: Agronomic and Molecular Characterization for Breeding Advances

Background and Objective: Salinity is a major constraint for sustainable rice production, and developing new rice varieties with inherent tolerance against this major abiotic stress will help achieve a sustained increase in rice production under unfavorable conditions. The present study was conducted to identify which of the rice promising lines possess the genetic capacity to withstand salt stress as compared to their tolerant parent. Materials and Methods: These experiments were carried out in a randomized complete design with three replications to test 14 rice genotypes under normal and saline stress at Sakha Research Station, Egypt, as normal soil, and El-Sirw, Damietta, as saline soil, respectively, during the 2022 and 2023 summer seasons. Further molecular analysis was applied. Results: The data obtained revealed a big variation among the tested rice lines as compared with their parents for the studied agronomical characteristics and molecular markers. The genotypes, including the elite lines and their parents, and all plant characteristics, were affected significantly and negatively by salinity stress. The rice genotype GZ12103-3-4-6-4 recorded the highest grain yield under normal soil at Sakha (11.23 ton/ha), while the genotype GZ12103-3-11-14-24-2 recorded the lowest grain yield under the same conditions. The GZ12103-3-4-6-4, GZ12103-3-4-6-1, and GZ12103-3-4-5-2 were the highest yielding genotypes under saline soil conditions (5.53 and 5.50 ton/ha) compared with their parents, GZ9461-4-2-3-1 and GZ9399-4-1-1-3-2-2 (2.80 and 3.63 ton/ha). The phenotypic coefficient of variability was higher than the genotypic coefficient of variability for all plant characteristics, indicating the environmental effect on the expression of these characters. While the biggest portion of PCV (%) was contributed by the genotypic component, less by the environmental component. Conclusion: Cluster analysis based molecular results revealed the separation of those three high-yielding genotypes together with their salinity tolerance parent GZ9399-4-1-1-3-2-2. Current results shed light on the incorporation of those advanced, promising lines in the breeding program for salinity tolerance.