Is root nutrient uptake a modular function？ A test using Solidago canadensis

• Published in: Journal of forestry research Vol. 27; no. 2; pp. 321 - 328
• Main Authors: Li, Shou, Mou, Pu, Hu, Fengqin
• Format: Journal Article
• Language: English
• Published: Harbin Northeast Forestry University 01.04.2016; Springer; The College of Life Sciences, Beijing Normal University, 19 Xinjiekouwai Avenue, 100875 Beijing,People's Republic of China%Institute of Soil, Chinese Academy of Sciences, 71 East Beijing Rd., 210008 Nanjing, People's Republic of China
• Subjects: ammonium nitrate; Biomedical and Life Sciences; Forestry; Life Sciences; nitrogen; nutrient uptake; O3处理; Original Paper; roots; Solidago canadensis; stable isotopes; transportation; 养分吸收; 加拿大一枝黄花; 去离子水; 根系; 模块化; 生命周期; 稳定同位素; Root module; Nitrogen uptake; Modularity; N; Solidago canadensis; 15N
• DOI: 10.1007/s11676-015-0151-8
• ISSN: 1007-662X

Plant roots have been recognized to be modu- lar, and a third order root cluster has been proposed to be the basic root module unit based upon the life cycle. This experiment examines root modularity of the nutrient-up- take function using stable isotope 15N. Solidago canadensis root clusters of second or third orders--from the same third or fourth order roots, respectively--were treated with 15NH15NO3, NH4NO3, and de-ionized water for 15 and 180 min. The δ15N values of the root clusters were then analyzed and compared. The 15N values of 15N-treated root clusters of both second and third orders were hundreds of times higher than that of the 15N untreated root clusters. However, the differences of the δ15N values among 15N untreated root clusters （though expressed some significant variations）, did not indicate the 15N shared by the sister root clusters came from a common higher-order root. These results demonstrated functional modularity of root nutrient uptake, revealed a second order root, perhaps even a first order root to be a base module unit in terms of root nutrient uptake. The results also suggested that the concept of root modularity is function-specific. This experiment further revealed the importance of treatment timing in stabilizing the internal 15N/14N ratio in roots and avoiding top-down transportation of 15N back into roots to secure unbiased measurements.