Abstract

Salt stress is an abiotic stress known to affect plant growth and distribution. In this investigation, this expectation was tested on germination, seedlings’ survival and genetic diversity of Robinia pseudoacacia (black locust). To do this, seeds of R. pseudoacacia collected from a natural population were sown on soil media of different salt concentrations (0.6, 1, 2, 3, 4, 5, 6, 7 and 8 g/kg), after which germination and seedlings survival rates were observed. Subsequently, genomic DNA was isolated from leaf samples for genetic analysis using 10 nuclear SSR primers. The results show that seed germination and seedling survival significantly reduced with increase in salt concentration. Specifically, R. pseudoacacia seedlings did not grow on soils with salt concentrations higher than 6 g/kg. As regards the effect of salt stress on genetic diversity of R. pseudoacacia seedlings, the overall result from 10 nuclear microsatellite primers revealed an increase in heterozygosity as salt concentration increased, which suggested selection against homozygosity under salt stress. This result further supports the fact that heterozygosity is one of the factors that ensures that tree populations are adaptable to salt stress. Therefore, management of forest tree populations should be geared towards managing genetic diversity in order to engender survival under salt stress.

Key words: Robinia pseudoacacia, salt stress, genetic diversity, nuclear microsatellite, adaptability.