Effect of pollen source and stigma receptivity on seed production in ten cultivars of Dianthus plumarius L.

Abstract

Dianthus plumarius L. is usually propagated vegetatively, but seed propagation is an option. However, erratic and often poor seed setting can be a problem in Dianthus spp. Pollen viability, stigma receptivity and the effect of pollen source on seed set were therefore investigated in ten "Hammett" D.plumarius cultivars. Pollen viability was high (>87%) in all ten cultivars. Hand pollination showed stigma receptivity was either nil or very low on the first day of flower opening, and generally peaked between the fourth and sixth days after flower opening, depending on cultivar. Pollen source determined the number of seeds produced, in that for some cultivars as pollen providers seed set was nearly double that when the same cultivars were pollen receivers. Seed set averaged 39% for all cultivars, but was greatest (64%) for cv. Far North when selfed, and lowest (14%) for cv. Spot On, also when selfed. Six of the cultivars were equally receptive to both self and cross pollination, but two (Far North and Neat and Tidy) produced more seeds after self pollination, while the other two (Spot On and Double North) produced more seeds after cross pollination. Reasons for the variability in seed setting are still to be determined.