Natural out crossing in common buckwheat.

Kedar. N. Adikari^1,2, and Clayton. G. Campbell³

¹ Department of Plant Science, University of Manitoba, Winnipeg, Canada R3T 2N2; ² Present address: Plant Sciences, faculty of Agriculture, University of Western Australia, Nedlands, WA 6907 Australia; ³ Agri-Food Diversification Centre, Morden, Manitoba, Canada R6M 1Y5

K.N. Adikari, and Clayton. G. Campbell. 1998. Natural out crossing in common buckwheat. Euphytica 102: 233-237.

Abstract: Common buckwheat is an obligate cross pollinating crop because of its sporophytic self-incompatibility system. Therefore a study to assess the extent of natural out crossing was undertaken for two years at Morden and Portage la Prairie, Manitoba using a semi-dwarf character, which is due to a homozygous genotype with regard to a recessive gene, as a marker. The semi-dwarf genotype was grown in 100 m rows running in four directions at 90° from a central 36 m² plot of a normal tall variety. At maturity, seed samples were taken from the semi-dwarf at designated intervals. At least 200 F₁ seeds of each sample were grown in the greenhouse to the 3-4 leaf stage and the proportion of tall plants was used to determine the percentage of out crossing. Approximately 50% out crossing occurred where the semi-dwarf plants were immediately next to the normal plants and then the proportion decreased with increasing distance. Although out crossing occurred throughout the distance tested, there was no significant differences from 12 m onward from the pollen source. Lack of directional influence in out crossing and a sharp reduction in the proportion of tall plants within a m distance from the pollen source suggested that wind was not a major factor in disbursing the buckwheat pollen over long distances. Although a substantial cross pollination was limited to a few metres from the pollen source, nearly 1% out crossing occurred even at 100 m. Since the distance in this experiment was limited to 100 m from the pollen source, the present results do not allow us to recommend the minimum isolation distance required to met certain standards for buckwheat seed production.

Key words: Fagopyrum esculentum, insect pollination, out crossing, varietal purity, wind pollination