Evaluation of Different Treatments to Improve Germination of Iris Spuria Subsp. Musulmanica

  Iris spuria subsp. Musulmanica is a rhizomatous herb growing as wild in Iran, Turkey and, Caucasia. This species is important from ornamental and medicinal perspective and could be used as flowering pot plant, cut flower and landscape plant. A few of Iris seeds germinate under natural conditions. Therefore, an experiment was designed to improve germination of Iris seeds using different treatments that could be accessible for floriculture purpose. This experiment was carried out based on completely randomized design with 10 treatments and 4 replications (each replication contains 25 seeds). Treatments were control without treatment, priming in hydroxide sodium 20M for 10 minutes, priming in sodium hydroxide 15M for 20 minutes, W100-10: in water 100°C for 10 minutes, W80-15: in water 80°C for 15 minutes, priming in sulfuric acid 98% for 10 minutes, priming in sulfuric acid 98% for 15 minutes, stratification for 30 days, stratification for 60 days, and stratification for 90 days. For all treatments, germination variables including germination, germination rate, mean germination time, seed vigor index, mean germination daily, shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, and root dry weight were measured. Treatment effect on germination variables was significant (p<0.05). The results improvement of that treating seeds with 20 mM of hydroxide sodium solution for 10 minutes led to improve the seed germination parameters like germination percentage, germination rate, seed vigor index, shoot and root length, fresh and dry weight of root and shoot compared to control. In three levels of stratification treatments, germination percentages were less than control treatment. Also, the results showed that treating seeds with sulfuric acid for 10 minutes improved as partially seed germination and other germination variables in comparison with control treatment. Previous studies revealed that the seed coating played an important role in seed dormancy of Iris species. In this study, scarification treatment with hydroxide sodium resulted in increased germination which may correspond to the reduced seed mechanical inhibitory and the improvement in gas and water exchange. Moreover, sodium hydroxide solution facilitated the seed germination via the elimination of seed coat and increasing the seed capsule Intercellular space which finally promoted the exchange of materials between seed and its surrounded environment. Like too many Iris species, a non-deep morphophysiological mechanism may play the most important role in dormancy of I. spuria subsp. Musulmanica.