Evaluating quinoa genotypes for salinity tolerance at germination and seedling stages is a prerequisite for plant breeders. Thus, the scrutiny of 19 quinoa genotypes at different salinity levels under controlled laboratory and greenhouse conditions occurred at the germination and seedling stages. This study aimed to identify the most tolerant genotypes to elevated salinity levels at germination and seedling stages and to determine the traits of a robust association with salinity tolerance using a factorial experiment based on a randomized complete block design in three replications. The four salinity solutions used were zero (control), 3000, 6000, and 9000 ppm NaCl. Increasing concentrations of NaCl caused a gradual and significant decrease for all studied traits except mean germination time, which significantly increased. At all salinity-stress levels (3000, 6000, and 9000 ppm NaCl), the studied 19 genotypes underwent classification based on their salinity tolerance index (STI) into three categories, i.e., tolerant, moderately tolerant, and sensitive. The four most salinitytolerant quinoa genotypes under all studied salinity-stress conditions were Rainbow-2, Ql3, RH, and KvlSRA2. The strongest correlations were between STI and each of seedling length, root length, seedling fresh weight, seedling vigor index I, and seedling vigor index II under 3000 ppm; germination percentage, speed germination index, seedling extent, root length, seedling fresh weight, and seedling vigor index II under 6000 ppm; and shoot length and seedling vigor index I under 9000 ppm salinity concentration level. Traits showing sturdy correlations with STI, high heritability estimates, high expected genetic advance, and wide phenotypic and genotypic variability were seedling dry weight, seedling fresh weight, seedling vigor index II, and speed germination index at all salinity stress concentrations; they are recommendable as selection criteria for salinity tolerance in quinoa at germination and seedling stages.
Quinoa, salinity tolerance, germination, seedling stage, selection criteria, heritability
The results will help quinoa breeders identify salinity-tolerant genotypes and the selection criteria for salinity tolerance in quinoa at the germination and seedling stages.