Somatic Polymorphism Variation in Crotalaria retusa L. Seeds

摘要

The article describes the somatic polymorphism in style="font-family:Verdana;">Crotalaria retusa style="font-family:""> style="font-family:Verdana;">L. seeds. Each individual may produce yellow dormant seeds, brown quiescent seeds and unviable dark brown ones. Therefore, regarding physiology it is a dimorphism. We style="font-family:""> style="font-family:""> style="font-family:Verdana;">show that autogamy reduces dimorphism, favoring the style="font-family:Verdana;">formation of dormant seeds. However, the significant variation in style="font-family:Verdana;"> dimorphism is seasonal as consequence of increased viability of dormant seeds under drier weather conditions. style="font-family:""> style="font-family:Verdana;">The variation is a phenotypic response to changes of humidity in the environment during plant reproduction, a mechanism inducing the prevalence of dormant seeds in the dry season style="font-family:""> style="font-family:""> style="font-family:Verdana;">and quiescent seeds during the rainy season. The seasonal alternation between dormancy and quiescence in seasonally dry environments has an apparent adaptive value. The chromatic polymorphism increases on the more humid coast and during the rainy season, due to increased mortality of dormant seeds under wetter weather conditions. Unviable seeds accumulate oxidized phenols in their seed coat that possibly act as induced chemical defenses. Its proportion increases with humidity, accentuating polymorphism, also in response to the increase in the predation rate by larvae of style="font-family:Verdana;">U. ornatrix style="font-family:""> style="font-family:Verdana;">during the rainy style="font-family:""> style="font-family:Verdana;">season.