Temperature-induced variation in reproductive success: field and control experiments with the C4 grass Echinochloa crus-galli

Abstract

To examine the influence of weather patterns on the flowering of a C4 plant, 11 transplant gardens were sown with seeds of Echinochloa crus-galli var. crus-galli within and beyond the species range. Both the isolated effect of climate and the joint effect of competition and soil quality on the flowering of E. crus-galli were analyzed. Although vegetative growth was significantly more vigorous in the southernmost site, Echinochloa plants were able to grow actively even at high latitudes. Conversely, flowering decreased gradually from south to north. The maximum temperature in August was the best predictor of floral emergence. Data from controlled experiments confirmed that flowering of E. crus-galli was size independent, and temperature was shown to have an effect on biomass accumulation and allocation as well as on floral emergence. Plants grown in the coolest thermoperiod produced a small number of heavy seeds, whose germinability was superior to that of plants grown in the other temperature treatments. Finally, the results indicate that maternal families represent a significant source of variability for reproductive characteristics. The presence of genetic effects suggests that E. crus-galli has the potential for further evolution with regard to temperature. Key words: flowering, reproduction, low temperature, C4 plants, Echinochloa crus-galli.