Annals of Botany

Seed behaviour: can we blame the mothers?

In cool temperate regions, an unusually cool, wet summer often results in some cereal seeds germinating on the parent plant. This is an extreme case of a more general phenomenon, namely that the conditions experienced by the parent plant during flowering and seed set can affect the dormancy and subsequent performance of the seeds. Although there have been many investigations of this, one group that has not been studied are Australian native plants. To remedy this deficiency, Hoyle et al. (St Lucia, Queensland, Australia and Royal Botanic Gardens, Kew, UK, pp. 93–101) have studied the effects of parental environment on seed dormancy in Goodenia fascicularis, a species that has potential for use in re-vegetation programmes. In G. fascicularis dormancy is broken by stratification in warm and damp conditions. Germination itself has a strong requirement for light. Thus, seeds that are shed in spring and which lie on or near the soil surface delay germination until the more favourable autumn conditions develop. In investigations of the effects of parental growth conditions plants were grown under two temperature regimes, 39/21 °C and 26/13 °C. In both regimes, some plants were well-watered while others had a limited water supply. The effects of temperature on growth were readily apparent: plants in the cooler environment were taller, with greater above-ground biomass. They set seed later and produced fewer seeds than in the warmer environment. However, seeds from the plants in cooler conditions had a higher level of viability. Seeds from both sets of plants were, as expected, dormant at maturity; however, those from the plants grown under warmer conditions were less dormant in that it took shorter periods of warm stratification to break dormancy. Water supply also had effect: in both temperature regimes, the water-restricted plants produced fewer, less-dormant seeds. Seed biology is thus subtly affected by maternal environment, exhibiting a physiological fine-tuning rather than a dramatic change in behaviour.