Exogenously-applied plant growth biostimulators increase the growth and productivity of Vicia faba plants

The use of plant growth biostimulators (PGBs), including diluted bee honey solution (BHS), silymarin (Sm) and iodine (I) can improve growth and productivity of crop plants, including faba bean (Vicia faba L.). BHS is rich in osmoprotectants, nutrients, vitamins, and many antioxidants making it effective plant growth biostimulator, compared to Sm or iodine, in increasing plant growth and productivity. Therefore, the present study was planned to investigate the potential improvement in leaf chlorophyll content, growth, and pods yield of V. faba plants by foliar application of BHS, Sm or iodine by using a completely randomized design. The enhancing impacts of these three PGBs were observed on leaf chlorophyll content, growth, and pods yield of V. faba plants. However, BHS (at a rate of 7.5 g L–1) was superior to Sm and iodine mediated further increases in leaf chlorophyll content, growth, and pods yield by 13.4 and 11.8%, 15.7–36.3 and 13.4–22.8%, and 20.0 and 22.7%, respectively. These results suggest the use of 7.5 g bee honey L–1 as a stimulator to increase the growth and productivity of V. faba plants.