Factors affecting in-vitro gynogenic haploid production in niger (Guizotia abyssinica (L. f.) Cass.)

The effects of growth regulators, cold-pretreatment of flower buds, ovule (embryo sac) developmental stage and genotype on induction of gynogenesis in unpollinated ovule cultures were assessed in niger (Guizotia abyssinica (L. f.) Cass.). Indirect callus-mediated gynogenesis occurred in cvs JNC-6 and Ootacamund when the ovules were cultured on MS medium supplemented with 30 g l(-1) sucrose and 2,4-D either alone (0.5-2.0 mu M) or in combination (2.0 mu M) with different cytokinins, such as adenine, BA, 2iP and kinetin (0.5-2.0 mu M). An optimum induction of gynogenesis was fostered on medium supplemented with 2.0 mu M 2,4-D and 1.0 mu M kinetin. Cold-pretreatment of flower buds had no stimulatory effect, but ovules collected one day before anthesis were most responsive to gynogenesis. The results showed significant variations in genotypic competence for gynogenesis with cv. Ootacamund being the most responsive (12.5%) and cv. IGP-76 the least (2.5%). Gynogenic embryos differentiated and matured on media (30 g l(-1) sucrose) supplemented with 0.5 mu M NAA plus 1.0 mu M kinetin, and 0.5 mu M ABA, respectively. The haploidy (2n = 1x = 15) of gynogenic plants was confirmed by cytological analysis.