Red Clover Seed‐Parent and Pollen‐Parent Correlated Reproductive Success and its Relationship to Polycross Mating Metrics

Abstract

Outbred forage species syn1 polycross seed production has a major impact on expected inbreeding depression in later seed increase generations. In this study, we examined the relationship between seed‐parent and pollen‐parent fecundity and how this relationship relates to other polycross mating metrics. Twelve bumble bee (Bombus impatience Cr.)‐pollinated red clover (Trifolium pratense L.) polycrosses ranging in size from 13 to 96 parents were evaluated for median seed yield per plant, seed‐parent fecundity Weibull distribution shape parameter λ‐values, pollen‐parent fecundity distribution λ‐values, and seed‐pollen‐parent fecundity correlations. Seed‐pollen‐parent fecundity correlations were significant and varied from r2 = 0.187 to 0.879 with a median value of 0.464. Seed‐pollen‐parent fecundity was negatively correlated with seed‐parent fecundity distribution λ‐values (r = −0.633), indicating that less panmictic polycross mating was associated with more correlated seed‐ and pollen‐parent fecundity. Multiple regression of a polycross's median seed yield per plant and seed‐parent fecundity distribution λ‐values onto seed‐pollen‐parent fecundity correlations revealed a positive slope with median seed yield per plant (partial r2 = 0.255) and a negative slope with seed‐parent fecundity distribution λ‐values (partial r2 = 0.400). This study reveals that seed‐ and pollen‐parent fecundity are correlated and that this correlation is higher when median seed yield per plant is lower and when polycross mating is less panmictic. To mitigate the impact of increased inbreeding due to this correlation, we recommend creating a stress‐free polycross environment that maximizes seed production per plant in the polycross.