Seasonal Changes in the Germination Response of Cyperus inflexus Seeds to Temperature and Their Ecological Significance

Abstract

Seeds of the summer annual sedge Cyperus inflexus Muhl. are innately dormant at maturity in autumn. Seeds afterripen in the field during winter and germinate in light over a wide range of temperatures in spring and early summer. Seeds that do not germinate during spring and summer are prevented from germinating in autumn and winter because they lose their ability to germinate at lower temperatures. During autumn and winter these seeds regain their ability to germinate at lower temperatures and may germinate the next spring or summer. This narrowing and widening of the temperature range for germination may continue for several years in ungerminated seeds, until light, temperature, and soil moisture all become favorable for germination at the same time. These seasonal changes in the germination responses of the seeds allow germination to occur in spring and summer, when plants can complete their life cycle, and they prevent germination in autumn and winter, when plants cannot complete their life cycle.