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Evaluating rice for salinity using pot-culture provides a systematic tolerance assessment at the seedling stage

Kakar, Naqeebullah, Jumaa, Salah H., Redoña, Edilberto Diaz, Warburton, Marilyn L., Reddy, K. Raja
Rice 2019 v.12 no.1 pp. 57
Oryza sativa, breeding, crop production, culture media, electrical conductivity, genes, genotype, ligases, parents, pot culture, principal component analysis, rice, roots, salinity, salt stress, salt tolerance, sand, screening, seedlings, shoots, soil heterogeneity, sowing, staple crops, stress response, weather
BACKGROUND: Rice (Oryza sativa L.) is one of the major staple food crops consumed globally. However, rice production is severely affected by high salinity levels, particularly at the seedling stage. A good solution would be the development of an efficient screening methodology to identify genotypes possessing genes for salt tolerance. RESULT: A new salinity tolerance screening technique using rice seedlings in pot-culture was tested. This method controls soil heterogeneity by using pure sand as a growth medium and minimizes unexpected extreme weather conditions with a movable shelter. Seventy-four rice genotypes were screened at three salinity treatments including high salt stress (electrical conductivity (EC) 12 dSm⁻ ¹), moderate salt stress (EC 6 dSm⁻ ¹), and control (no salt stress), imposed 1 week after emergence. Several shoot and root morpho-physiological traits were measured at 37 days after sowing. A wide range of variability was observed among genotypes for measured traits with root traits being identified as the best descriptors for tolerance to salt stress conditions. Salt stress response indices (SSRI) were used to classify the 74 rice genotypes; 7 genotypes (9.46%) were identified as salt sensitive, 27 (36.48%) each as low and moderately salt tolerant, and 13 (17.57%) as highly salt tolerant. Genotypes FED 473 and IR85427 were identified as the most salt tolerant and salt sensitive, respectively. These results were further confirmed by principal component analysis (PCA) for accuracy and reliability. CONCLUSION: Although tolerant genotypes still need to be confirmed in field studies and tolerance mechanisms identified at the molecular level, information gained from this study could help rice breeders and other scientists to accelerate breeding by selecting appropriate donor parents, progenies and potential genotypes at early growth stages necessary for salinity tolerance research.