Assessment of salinity tolerance in polycross progenies of tall fescue [Lolium arundinaceum (Schreb) S. J. Darbysh.)]

Abstract

The effect of salinity on germination factors was evaluated for twenty five genotypes as the parents and first generation synthetic progenies (Syn1) of tall fescue. To produce polycross seeds, four groups of six parental plants with contrasting levels of diversity based on phenotypic traits and contrasting levels of AFLP molecular marker diversity constructed. An experimental factorial, in a randomized complete block design was conducted under five salinity levels (0, 50, 100, 150, 200 mM NaCl). In each experiment 10 ml from salt solution was added to each Petri dish. Seeds were allowed to germinate at 25 ± 1°C for 14 days. Daily, final germination and emergence percentage, as well as germination and seedling emergence rate, and seedling fresh and dry weight were measured in the study under controlled and stress conditions in parental genotypes and also first generation progenies. The results showed that the differences between parents of populations were not significant for the evaluated traits but the effect of population in progenies were significant for all of the evaluated traits. It seems that the polycrosses of the parental genotypes gathered the positive genes in progenies and caused the significant increases in the evaluated traits such as germination percent, germination rate, fresh weight of leaf and radical length. HMD and LMD populations had the highest means for most of the evaluated traits such as germination percentage and germination rate in all stress and non-stress conditions. The parents of these population selected based on molecular markers diversities. The correlation between similarity matrix of parents based on molecular markers and the similarity matrix of first generation of progenies based on morphological traits was significant (r=0.35). The highest broad sense heritability was observed for fresh weight of radical in parents and progenies (70% and 80%), while the lowest was observed for radical length in both parents and progenies (13% and 15%). Our results demonstrate that molecular markers can be reliable tools to efficiently selecting parental genotypes and improving tall fescue breeding programs.