Ascorbic acid (AsA) has different roles in plant metabolism. Current research was done to evaluate the effect of various concentrations of AsA on growth and micropropagation of Aloe barbadensis Mill., an important medicinal and ornamental herb, for the first time. In this regards, results obtained from applying different concentrations of AsA on variables of aerial part length, length and number of root, number of propagule, brownness of medium, and fresh and dry weights of plants were analyzed after 8 weeks. Control plants showed slower growth in aerial parts than plants treated by AsA. Also, leaves were smaller in control plants. Fresh and dry weights in aerial parts were less in control plants than those of treated with AsA. There was a significant increase in produced numbers of propagules in different treatments compared with control treatment. Average number and length of produced roots in plants treated with AsA were more than those of produced in roots of control plants. In addition, brownness of medium and tissue cultures were reduced in plants treated with AsA, due to existence of different phenolic compounds in these plants. Totally, 80 mg L-1 AsA had the highest effect on induction of growth and development of A. barbadensis Mill. in vitro. تفاصيل المقالة

Seed germination of some woody species is done with difficulty and at a low rate due to various reasons, including physiological and mechanical dormancy and the presence of inhibitory substances in the seed tissues. Priming is one of the most important treatments to increase the germination capacity of seeds. The purpose of this study was to investigate the effect of different treatments of stratification and sulfuric acid on the growth and germination percentage of Robinia pseudoacacia, Ailanthus altissima and Fraxinus excelsior seeds. This research was done as factorial in the randomized completely block design with two factors; plant and stratification in four replications. The results showed that the highest percentage of germination (72%) was obtained in the 50% sulfuric acid treatment on R. pseudoacacia, seeds and the lowest one (18 and 12%) in the control and 95% sulfuric acid treatments on F. excelsior seeds, respectively. The overall results of this research showed that the best stratification treatment for most of the measured traits was 50% sulfuric acid and 3°C cold for 20 days. تفاصيل المقالة