Environmental adaptability of the genus Carex-A case study of Carex heterostachya and Carex breviculmis in northwest China

Carex heterostachya (CH) and Carex breviculmis (CB) are easy to develop lawns in a short period and exhibit high ornamental value in northwest China. So, what type of plant functional traits has they formed for long-term survival and adaptation to this environment, which plant is more adaptable, as well as which leaf functional traits are critical to photosynthetic characteristics. The result of this study suggests that (1) CB is a slow investment-return plant with strong environmental adaptability and plasticity in long-term shaded environments. It is characterized by its weak photosynthetic capacity, smaller specific leaf area, low CO2 compensation point, high water utilization rate, high maximum carboxylation rate, as well as dark breathing rate. Moreover, it also has a thick cuticle, and epidermal cells make CB resistant to drought and barrenness. (2) CH is a quick investment-return plant, which is characterized by its higher photosynthetic rate, transpiration rate, stomatal conductance, as well as larger specific leaf area. With the increase of the temperature and photosynthetically active radiation, CH maintains high photosynthetic capacity by decreasing the transpiration rate and increasing the utilization rate of light energy. Its conducting tissue is well developed. CH have lower light saturation points and light compensation points, and CH was more shade-tolerant than CB. (3) Carex have strong environmental adaptability, large variation in leaf structure traits, as well as strong plasticity. Leaf anatomical characters are stable, whereas there are differences in the interspecific variability and plasticity. (4) Specific leaf area (SLA) can serve as the main factor affecting the photosynthetic availability of Carex, the thickness of the stratum corneum(CUT), the thickness of the upper(UET) are secondary factors. These finding can provide a theoretical basis for the cultivation and application of Carex and the expansion of turfgrass germplasm resources.