Response of Oryza glaberrima Steudel to Salt Stress at Seedling Stage

Abstract

Salt stress is one of the major environmental challenges that limit rice 
production globally. As climate change exacerbates this issue, the development 
of salt-tolerant rice varieties has become crucial for sustaining food security. 
This study evaluated the salt tolerance of Oryza glaberrima genotypes and 
explored the genetic associations of salt tolerance using tagged SSR markers. 
The research was conducted under hydroponic conditions at the Department of 
Botany, Ahmadu Bello University, Zaria, using standard methods. Forty-three 
Oryza glaberrima genotypes were studied. The genotypes were sown in 
styrofoam floats suspended in 15-liter, four-cornered, dark-coloured plastic 
bowls. After seven days, 1 g of FeSO4 and 10 g of Peter’s 20-20-20 water
soluble fertilizer were added to the nutrient solution. Subsequently, NaCl, 
FeSO4 and fertilizer were added to simulate saline conditions. Plant biometrics 
were evaluated, and DNA was extracted from young leaf samples. PCR 
amplification with seven SSR primers associated with salt tolerance revealed 
significant genetic variation among the genotypes. The response to salt stress 
was genotype-dependent, with approximately 14% of the genotypes showing 
tolerance or moderate tolerance, while 86% were highly susceptible to salt 
stress. The susceptible genotypes exhibited severe visual symptoms of salt 
injury. Two distinct genetic clusters were observed based on the SSR markers, 
with the majority of the susceptible genotypes (97.3%) clustering in one group, 
except for TOG14101, which clustered separately. The study confirmed that 
SSR markers are effective tools for distinguishing between salt-tolerant and 
susceptible Oryza glaberrima genotypes, providing valuable insights for 
breeding programmes.