More isn’t always better – The effect of environmental nutritional richness on male reproduction of Taxus baccata L.

Abstract

Limited pollen availability contributes to lower seed production, especially in dioecious species. It can result from a lower quantity and/or a lower quality of pollen grains. Since the environment can impact pollen development, the effect of long-term nutritional availability on the male parameters of the dioecious, long-lived plant, Taxus baccata was investigated. The quantity (production of male flowers) and quality (pollen viability and germination under in vitro conditions, pollen volume, morphology, carbon and nitrogen content) of pollen grains collected from plants growing under different nutritional conditions were analyzed in a long-term pot experiment. Although plants grown in a poorer nutritional environment produced fewer male flowers, they produced pollen grains with greater viability and longevity (e.g. better morphology after in vitro incubation, higher germination rate). Pollen grains also exhibited differential morphology and chemical composition in different nutritional environments. Moreover, it was found that the C: N ratio can be used as a potential marker of pollen viability. Collectively, these results clearly demonstrate the impact of the nutritional environment on pollen grain development. In summary, male plants growing in poor nutritional environments produced a lower number of pollen grains because they produced fewer male flowers, but the pollen produced had much better quality, relative to pollen grains produced in much richer nutritional conditions.