Pollen allelopathy among sympatric grassland species: in vitro evidence in Phleum pratense L.

Abstract

summaryPollen extracts from live locally‐common grassland species in eastern Ontario, Canada were tested for in vitro allelopathic effect on the pollen germination of 17 sympatric target species in 1987. The flowering phenologies of the test and target species were recorded to determine if any phenologically‐divergent species showed evidence of in vitro pollen‐allelopathic interactions. Phleum pratense L. demonstrated pollen‐allelopathic effects on all targets except Linaria vulgaris Hill. P. pratense also exhibited significant phenological divergence with seven of the target species. Pollen extracts from Agrostis stolonifera L., Melilotus alba Desr., and Vicia cracca L. inhibited pollen germination in some of the target species, but the results suggest that these effects were pH‐mediated. The pollen extract of Erigeron annuus (L.) Pers. did not cause inhibition of pollen germination in any of the target species. Further tests with pollen extract of P. pratense and another 23 sympatric target species were performed in 1988. Pollen germination was significantly inhibited in all but two of these species: A. stolonifera and P. pratense. Hence the pollen of P. pratense was not auto‐allelopathic. The breeding system, relatively tall growth habit and relatively large quantity of pollen produced all support the in vitro evidence of P. pratense as a pollen‐allelopathic species.