Evaluation of Segregating Tomato Lines for Salinity Tolerance

Salinity is a major abiotic stress affecting plant growth and productivity during all developmental stages. Responses of fourteen tomato genotypes to salinity was investigated using five water salinity levels of NaCl (0.5 control treatment, 2.4, 4.8, 7.2, and 9.6 dS·m^-1 ) through drip irrigation system. Based on the performance of the tomato genotypes at different salinity levels, L46, L66, and L56 genotypes were selected to represent salinity susceptible, moderately salinity tolerant and salinity tolerant genotype, respectively. The salt-tolerant breeding line BL 1076, was also selected as a reference for salinity tolerance. Development of the genetic populations (parents, F₁s and F₂s) were produced. The data of the first generation hybrids under both reference and high salinity levels reflected pronounced hybrid vigor on the general performance of some vegetative growth traits, fruit number and total yield. In all families, the F₁ hybrids showed significant superiority in fruits’ number and total yield over their respective higher parents. This general trend, apparently, indicated that the inheritance of these traits involved complete- to over -dominance for high over low number of fruits and total yield per plant. The comparisons between the two successive generations, the F₁ vs. F₂ within each family, reflected an obvious inbreeding depression on the general performances of the these traits. In all cases, the F₂’s were significantly lower in number of produced fruits and total yield than those of their respective F₁ parents. Primers for qPCR were engineered to be on two consecutive exons spanning an intron. The qPCR fold increases were detected for all selected probe for the salinity tolerant L56 under salinity stress compared to the reference similar to gene expression data. However, some genes  showed higher fold increase in expression than in qPCR, e.g. four time increase for the Les.4483.1.S1. Similar trends were also revealed for the salinity intermediate L66 under salinity stress compared to the reference.