Germination, Growth and Seedling Quality Index of Common Ash in Immature and Mature Seed

The aim of this study was to investigate the effect of seed maturation on germination, growth and seedling quality index of common ash (Fraxinus excelsior L.) in Kelardasht forest nursery. In 2017, the seeds of immature in late August and the seeds of mature in late November were collected and following stratification in moist sand were sown in nursery bed in mid-Feberaury each with three 100-replications . From the mature seeds, some of them germinated in 2nd year (April 2018) and the seed germination, biomass and quality indices of their seedlings were statistically (paired t-test) compared with the results of immature seeds germinated in spring 2017. The highest percentage of cumulative germination allocated to the immature seeds, followed by mature seeds germinated in 2nd year. Due to the lack of germination of most of the mature seeds in spring 2017, showed the seed dormancy, their germination traits were not considered in the statistical test. Germination percentage, mean germination time and germination speed and also, dry biomass, root biomass, root length and seedling quality index in immature seeds were greater than those in mature seeds germinated in second year. Generally, it is best to collect the seedlings of immature seed in order to achieve the optimum germination and growth, because the mature seeds are often dormant and unable to germinate during the first growing season. If mature seeds are supplied, it is advisable that these seeds to be stratified until spring of the second year.