The aim of this study was to duble the chromose number of elephantgrass and pearl millet triploid hybrids in order to obtain hexaploid fertile plants. This strategy would allow the use of the hexaploids in the elephantgrass breeding program as a bridge for transfering alleles of desired characteristics and making possible propagation by seed. Seedlings, plantlets and stem segments were cultivated in vitro and treated with 0.05% or 0.1% colchicine for 12 or 24 h. Seedlings of different hybrid genotypes and meristems of two interspecific hybrids were cultivated in vivo and treated for 24 h with 0.05% colchicine. Chromose duplication was confirmed by countings in the root tip cells. Pollen viability, in vitro germination tests and seed production were used to evaluate the fertility of the hexaploids. Seedlings cultivated in vitro and treated with 0.1% colchicine for 24 h were the most efficient method of polyploidy induction, as 38% of the surviving plants have twice the number of chromose viable pollen grains and fertile seeds.
Chromose duplication; colchicine; polyploidy; interespecific hybrid; Pennisetum purpureum; P. glaucum
