Pollination and fertilization in crops of Vicia faba

Abstract

Crops of faba beans (Vicia faba cv. Fiord) were surveyed for the frequencies of pollination of stigmas, and fertilization of ovules, based on the detection of pollen tubes by fluroescence of aniline blue fluorochrome. The frequency of pollination ranged from 89.8 to 99.6% over crops, with an overall mean of 96.8%. Pistil fertilization varied from 88.4 to 99.1% about a mean of 95.5%; overall, 82.2% of all ovules examined were fertilized. There was no significant main effect of flower position in the raceme, although there were significant crop x floral position effects on fertilization. Mean ovule fertilization rate declined from a mean 91.6% for ovule 1 closest to the stigma to 56.7% for the fourth. Pollination was the controlling factor in the steps toward fertilization, there being a 99% likelihood that pistil fertilization would occur following pollination. It was concluded that neither pollination nor fertilization were limiting seed yield in these crops. There was also no evidence that measurable postfertilization abortion of ovules occurred, but that reductions in potential yield occurred owing to pod abortion.