Effects of Seed Nano-priming with Multiwall Carbon Nanotubes (MWCNT) on seed germination and seedlings growth parameters of mountain ash (Sorbus luristanica Bornm.)

A comprehensive study on breaking dormancy of mountain ash(Sorbus luristanica Bornm.) endemic species is still lacking. Here, the high efficient potentials of multiwall carbon nanotubes were used to break seed dormancy and improve seed germination in mountain ash. First, the seeds were primed with different concentrations of the nano-material including 0, 75, 150, 250, 350 and 500 mg l-1 during 24 hours. Then warm (two weeks) and cold (three or four months) stratifications were performed. The results showed that the seeds require cold stratification for at least 3 months. After the cold stratification period, the seeds were transferred to petri dishes in germinator. Daily seed germinations were recorded during 22 days. Eventually seed germination parameters such as seed germination percent, germination speed as well as mean germination time were calculated and compared. To understand the effects of nano-materials on the seedlings from different treatments, the subsequent growth of seeds was studied. The results revealed that all germination parameters were improved by 350 mg l-1 treatment. The microscopic seed observations showed that the nano-priming treatments led to seed endocarp abrasion and increased oxygen and moisture infiltration into seeds. Increasing root height growth was associated with the most considerable effects of treatments. Conclusively, it seems that increase in seedling moisture is one of the functional mechanisms of the MWCNT.