Plasticity of reproductive traits responding to variation in light availability at the rosette stage of the first year in a strict biennial, Pedicularis torta, from a field on the Qinghai-Tibet Plateau, China

Light is a fundamental heterogeneous environmental factor for plants and often varies at both spatial and temporal scales. In the present study, we carried out a shading experiment to investigate the effect of variable light availability at the rosette stage of the first year in the strict biennial species Pedicularis torta (an endemic species of the Qinghai-Tibet Plateau) on reproductive traits (i.e. total number of flowers per plant, total number of fruits per plant/total number of flowers per plant, the number of seeds per fruit, mean individual seed mass and estimation of the total number of seeds per plant, plant size at maturity in the second year and on the relationships between reproductive traits and plant size at this stage). We found that light availability affected most of the reproductive traits (except for mean individual seed mass), plant size at maturity in the second year, and the relationship between the total number of flowers per plant and plant size at this stage. Our results indicate that reproductive traits respond to changes in light availability during the rosette plant stage.