Borage plant (Borago officinalis L.) is an herbaceous annual plant. It was used as a medicinal plant since ancient times. Seed oil of this plant has been used to treat many skin disorders. It is the richest plant source of gamma-linoleic acid (GLA). However, seed production of borage is limited by flower and seed abscission. Ethylene is responsible for plant organs abscission which may be inhibited by silver ion (Ag+). Therefore, this experiment was designed to study the effect of nano silver and silver nitrate on abscission and yield of seed in borage. The study was carried out in a randomized block design with three replications. Four levels of either silver nitrate (0, 100, 200, and 300 ppm) or nano silver (0, 20, 40, and 60 ppm) were sprayed on borage plant at seed growth stage. The results showed that there was no significant difference between 100 ppm of silver nitrate and 60 ppm concentration of nano silver on the shoot silver concentration. However, increasing the concentration of silver nitrate from 100 to 300 ppm caused a decrease in seed yield. On contrast, a raise in the concentration of nano silver from 20 to 60 ppm has led to an improvement in the seed yield. Additionally, the lowest amount of seed yield was found with control plants. Finally, with increasing level of silver nitrate, the polyphenols compounds content were raised, but the enhancing level of nano silver resulting in the reduction of these components. In conclusion, nano silver can be used instead of other compounds of silver.
