Screening for salinity tolerance in rice landraces through morphological and molecular markers

Salinity stress is a major challenge to global rice production and agricultural sustainability, especially as climate change intensifies its impact. This study highlights the need for salinity-tolerant rice genotypes to support climate-resilient agriculture. Seventeen traditional rice landraces were evaluated alongside a salt-tolerant check (PTB 33) and a susceptible check (IR 64) using phenotypic and molecular approaches. Phenotypic assessments included germination percentage, salt tolerance index, seedling growth and growth reduction under NaCl-induced salinity levels of 2500 ppm, 5000 ppm, 7500 ppm and 10000 ppm. Molecular characterization involved 20 simple sequence repeat (SSR) markers, of which six (RM 8094, RM 237, RM 314, RM 3412, RM 562 and RM 284) were identified as polymorphic. The polymorphic information content (PIC) values were calculated for all six markers to assess marker informativeness. Genetic diversity analysis using DARwin 6.0 software grouped genotypes into four distinct clusters, demonstrating substantial variability. Among the genotypes, Kothamalli Samba showed strong salinity tolerance with high germination rates, robust seedling growth and minimal growth reduction across all salinity levels. Maikuruvai and Nellaiyappar exhibited moderate tolerance, whereas Kallundai was highly susceptible. The molecular findings corroborated the phenotypic results, offering valuable insights into the genetic basis of salinity tolerance. These findings provide a foundation for developing mapping populations and precision breeding strategies aimed at enhancing salinity resilience in rice. By leveraging genetic diversity, breeders can optimize heterosis, accelerate the development of high-yielding, salt-tolerant rice varieties and strengthen climate-resilient agriculture.