Inter-population variabilities in seed mass and germination of Panicum turgidum and Pennisetum divisum in the desert of Kuwait

Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation purposes.The knowledge of germination and dormancy patterns among populations of desert grasses is crucial for determining the potential of the species and populations to be used for restoration and conservation as well as forage production.Variability in seed germination of Panicum turgidum Forssk and Pennisetum divisum(Gmel.)Henr.in the desert of Kuwait was evaluated in different populations in May 2017.Experiment of seed germination(25 seeds and 4 replicates)was conducted for each population at night/day temperatures of 15℃/20℃and 20℃/30℃under the following light condition:continuous darkness or 12 h/12 h light/dark.Results showed that seed masses of both species strongly varied according to their seed provenances,and both species produced heavier seeds in population with a higher soil electrical conductivity.Seed germination percentage considerably varied between two species,and the variation in P.turgidum was greater(17%–49%)than that of P.divisum(72%–93%).Germination percentage in P.turgidum was greater at high temperature(20℃/30℃)than at low temperature(15℃/20℃).However,temperature regimes had no effect on germination percentage of P.divisum seeds.Mean germination time of both species exhibited significant inter-population variability.This result is especially relevant to assure the selection of the best population of each species and the regeneration success of the species.Besides this,inter-population variability also provides valuable information for enhancing our understanding of the mechanisms that regulate seed germination and how they might be related to seed provenance.

Seed provenance determines germination responses of Rumex crispus (L.) under water stress and nutrient availability

Aims Seeds of Rumex crispus from six provenances were studied in relation to their germination under drought and presence of nitrogen in the germination and emergence media.We also investigated whether adaptation to soil increases the ability of the species to colonize and establish in contrasting environments along a longitudinal gradient in western Spain by means of a reciprocal transplantation experiment.Methods We conducted a germination trial in the lab to test for the germination responses to water scarcity along a polyethylene glycol gradient and to varying concentrations of nitrogen compounds.Simultaneously reciprocal transplantations experiment was conducted,where seeds from six provenances were grown in the soils from the very same provenances.Seedling emergence,survivorship and fitness-related variables were measured in all plots.Important Findings We found that R.crispus has a cold-stratification requirement that enhances its germination.Significant differences between the six provenances were detected for time-to-germination,total seedling emergence,plant mortality and reproductive effort in all the experiments.The differences between provenances with respect to germination were confirmed by the significant statistical analyses of the variance,thus providing evidence that seeds from parent plants grown in different environmental conditions have an intrinsically different abilities to germinate and establish.Soil nitrogen content where seed germination and seedlings establish also play an important role in their performance in terms of survivorship and reproduction,being the higher levels of inorganic nitrogen and of microbial biomass those that increased biomass production,enhanced inflorescence formation and reduced plant mortality.We conclude that one of the main reasons for the spread and maintenance of R.crispus would be the increased levels of nitrogen in agricultural soils.