Plant growth regulators improve in vitro flowering and rapid generation advancement in lentil and faba bean

Rapid generation technology (RGT) involves applying plant growth regulators to accelerate in vitro flowering and the use of immature seed to shorten the time required to produce the next generation of plants. The effect of different concentrations of flurprimidol and combinations of one cytokinin and two auxins on in vitro flowering was evaluated using two lentil (Lens culinaris Medik.) and two faba bean (Vicia faba L.) cultivars. Adding flurprimidol to the medium reduced the internode length of plants, and plant height was decreased to approximately 10 cm in both species. The optimal concentration of flurprimidol depended on the species and the light intensity. The combination of 0.3 mu M flurprimidol, 5.7 mu M indole-3-acetic acid, and 2.3 mu M zeatin resulted in 100% of faba bean plants flowering and 90% setting seed. The combination of 0.9 mu M flurprimidol, 0.05 mu M 4-chloroindole-3-acetic acid, and with a perlite growth substrate resulted in 90% of lentil plants flowering and over 80% with seed set. However, faba bean showed better response with agar as the substrate. Under optimized conditions, a single generation cycle was achieved in 54 d for faba bean and 45 d for lentil. RGT could produce seven and eight generations per year for faba bean and lentil, respectively. For the single seed descent breeding method for self-pollinated plants, a seed of each plant in each generation is advanced three times per year until near-homozygosity, thus requiring more than 2 yr. The RGT method produces about double the number of generations per year and therefore has potential for significant acceleration of pulse crop breeding programs.