title: Root features related to plant growth and nutrient removal of 35 wetland plants.
abstract: Morphological, structural, and eco-physiological features of roots, nutrient removal, and correlation between the indices were comparatively studied for 35 emergent wetland plants in small-scale wetlands for further investigation into the hypothesis of two types of wetland plant roots (Chen et al., 2004). Significant differences in root morphological, structural, and eco-physiological features were found among the 35 species. They were divided into two types: fibrous-root plants and thick-root plants. The fibrous-root plants had most or all roots of diameter (D) ≤ 1 mm. Roots of D > 1 mm also had many fine and long lateral roots of D ≤ 1 mm. The roots of these plants were long and had a thin epidermis and a low degree of lignification. The roots of the thick-root plants were almost all thicker than 1 mm, and generally had no further fine lateral roots. The roots were short, smooth, and fleshy, and had a thick epidermis. Root porosity of the fibrous-root plants was higher than that of the thick-root plants (p = 0.001). The aerenchyma of the fibrous-root plants was composed of large cavities which were formed from many small cavities, and distributed radially between the exodermis and vascular tissues. The aerenchyma of the thick-root plants had a large number of small cavities which were distributed in the mediopellis. The fibrous-root plants had a significantly larger root biomass of D ≤ 1 mm, of 1 mm < D < 3 mm, above-ground biomass, total biomass, and longer root system, but shorter root longevity than those of the thick-root plants (p = 0.003, 0.018, 0.020, 0.032, 0.042, 0.001). The fibrous-root plants also had significantly higher radial oxygen loss (ROL), root activity, photosynthetic rate, transpiration rate, and removal rates of total nitrogen and total phosphorus than the thick-root plants (p = 0.001, 0.008, 0.010, 0.004, 0.020, 0.002). The results indicate that significantly different root morphological and structural features existed among different wetland plants, and these features had a close relationship to nutrient removal capacity.
authors.affiliation: Key Laboratory of Ecology and Environmental Science of Guangdong Higher Education, College of Life Science, South China Normal University, 510631 Guangzhou, PR China.
authors.forename: Wen-Ling
authors.initials: WL
authors.lastname: Lai
authors.forename: Shu-Qiang
authors.initials: SQ
authors.lastname: Wang
authors.forename: Chang-Lian
authors.initials: CL
authors.lastname: Peng
authors.forename: Zhang-He
authors.initials: ZH
authors.lastname: Chen
mesh_terms: D018533:Biomass; D010788:Photosynthesis / Q000502:physiology; D063245:Plant Development; D018517:Plant Roots / Q000033:anatomy & histology* / Q000254:growth & development* / Q000378:metabolism; D010944:Plants / Q000033:anatomy & histology* / Q000378:metabolism; D053833:Wetlands