Production of Hybrid Seeds by Intraspecific Crossing in Yam Dioscorea alata L

Manual crosses were carried out over two successive years on Dioscorea alata for the production of hybrid seeds between five females and seven males� parents with contrasting characteristics. A total of 22951 flowers were manually pollinated in both years (14145 in 2016 and 8806 in 2017) in 33 parental combinations. The ploidy levels of the parents were determined by flow cytometry. The crossed parents were all diploids except the female OA49 which was triploid. In both years the fruiting and seed rates were comparable (25.06 % and 22.82 %; 30.05 % and 30.18 %). A significant variation in fruiting rates was observed between the different parental combinations. Analysis of variance have shown that there is both a male effect on the fruit setting. The lowest rates were observed in combinations involving male clones 23 and Ma01 (2.04 % and 2.77 %) and the highest rates involved males TDa00/00128 and TDa00/00095 (48.25 % and 33.91 %). The triploid female OA49 is sterile. Females TDa01/00003, TDa01/00018, TDa99/00240 and TDa01/00295 gave comparable fruiting rates which are respectively (37.87 %, 29.38 %, 24.70 % and 20.92 %). For seeds production, there is no male and female effect. The fruiting rate according to the time slot depends on each male variety involved. For some males, the fruiting rate is influenced by the time slot of pollination while for others, there is no time slot effect on the fruiting rate.