Influences of Thidiazuron Concentrations and Exposure Duration on Axillary Shoot Proliferation of Faba Bean [Vicia faba (L.)] Genotypes

Abstract

Background: Faba bean is one of the most important feed grain legume crops in the world. However, this crop is a recalcitrant species for in vitro regeneration. Methods: In this study, in vitro shoot proliferation of ten faba bean genotypes, that are classified according to their seed size into small, medium and large, were investigated in response to different light regimes and thidiazuron (TDZ) treatments. Result: Incubation under different light regimes, explant type as well as genotypes influenced seedling growth and axillary shoot multiplication of faba bean. The explants with single cotyledon and incubated under continuous darkness for 6 days resulted higher number of shoot than nodal explants. Medium size seeded genotype (ILB4347) produced the highest shoot and root length and shoot proliferation as compared with large (Luz) or small (Triple White) seeded genotypes. The effects of TDZ concentrations (2-10 mM/L) and exposure duration (10 and 20 days) on axillary shoot multiplication were investigated for the ten faba bean using cotyledonary explants. The overall mean of TDZ time exposure showed that treatment of 20 days exposure had higher number of shoot compare to 10 days exposure treatment with 3.77 shoot per explant. On the basis of genotype used, the three most responsive genotype in tissue culture were medium sized seeds genotypes (ILB4347, Hassawi 2 and Misr 3 with 4.76, 4.40 and 4.15 shoot per explant, respectively). ILB4347 were the most responsive genotype in tissue culture. Treatment of 8 mM TDZ after 20 days followed by 2 weeks on MS medium without PGRs generated the highest proliferation with 6.63 shoot per explant. These findings contribute towards effective in vitro propagation of faba bean.