Phenotypic plasticity of sowthistle and its offspring in response to light availability

An indoor study was conducted to assess the effects of both light quantity and quality (green shade) on the development and performance of sowthistle and its offspring. The stands of sowthistle were grown at three different levels of light availability (50, 70, and 100%), and their phyllochron, height, number of branches and biomass were measured. To determine whether maternal environment influences the growth of offspring, seeds from the sowthistles grown under deep shade were planted in an optimum condition and a range of morphological characters measured. Although light availability had significant effects on the growth and development of sowthistle, there was no effect on offspring performance. Sowthistle canopy biomass was decreased by up to three and two times when the light availability was about 50 and 70%, respectively. In lower light availability (50%), the number of branches was suppressed up to nine fold. The results supported the concept that environmental light controls the growth of sowthistle and decreases the number of seeds but it does not have any effects on the quality of seeds and the performance of the next generation.