title: Contrasting responses to water-deficit among Encelia canescens populations distributed along an aridity gradient.
abstract: OBJECTIVE
  Drought is the most limiting factor for plant growth and recruitment in arid environments. For widespread species, however, plant responses to drought can vary across populations because environmental conditions can vary along the range of the species. Here, we assessed whether plants of Encelia canescens from different populations along an aridity gradient in the Atacama Desert respond differently to water-deficit conditions.
  
  
  METHODS
  We conducted a common-garden experiment using plants grown from seeds from three populations distributed along an aridity gradient to test for differences in relative growth rate (RGR), biomass, root to shoot ratios, and photosynthesis between watered and water-deficit plants. Additionally, we examined the relationship between root to shoot ratios with RGR and total plant biomass along the gradient.
  
  
  RESULTS
  Water deficit affected root to shoot ratios, biomass, and RGR, but not photosynthesis. Populations varied in RGR and biomass; plants from the most arid population had higher RGRs, but lower biomass than those from the least arid population. In watered conditions, root to shoot ratios did not vary with RGR or biomass. Conversely, with the water deficit, root to shoot ratios were negatively and positively related to biomass and RGR, respectively.
  
  
  CONCLUSIONS
  Response to water deficit differed among E. canescens populations; plants from the lowest rainfall environment adjusted root to shoot ratios, which may have allowed for equal biomass production across treatments. In contrast, plants from the wettest population did not adjust root to shoot ratios, but were reduced in biomass. These morphological and physiological changes to water availability showed that populations can use different strategies to cope with water deficit.
authors.affiliation: Universidad de La Serena, Departamento de Biología, Raúl Bitrán #1305, Colina El Pino, La Serena 1720170, Chile Instituto de Ecología y Biodiversidad (IEB), Santiago, Chile.
authors.forename: Danny E
authors.initials: DE
authors.lastname: Carvajal
authors.affiliation: Universidad de La Serena, Departamento de Biología, Raúl Bitrán #1305, Colina El Pino, La Serena 1720170, Chile Instituto de Ecología y Biodiversidad (IEB), Santiago, Chile aloayza@userena.cl.
authors.forename: Andrea P
authors.initials: AP
authors.lastname: Loayza
authors.affiliation: Universidad de La Serena, Departamento de Biología, Raúl Bitrán #1305, Colina El Pino, La Serena 1720170, Chile Instituto de Ecología y Biodiversidad (IEB), Santiago, Chile Centro de Estudios Avanzados en Zonas Áridas (CEAZA), La Serena, Chile aloayza@userena.cl.
authors.forename: Francisco A
authors.initials: FA
authors.lastname: Squeo
mesh_terms: D019659:Asteraceae / Q000254:growth & development / Q000502:physiology*; D002677:Chile; D003889:Desert Climate; D055864:Droughts; D010788:Photosynthesis; D018517:Plant Roots / Q000254:growth & development / Q000502:physiology; D018520:Plant Shoots / Q000254:growth & development / Q000502:physiology; D014867:Water / Q000502:physiology
chemical_list: D014867:Water
keywords: Asteraceae; Atacama Desert; Encelia canescens; aridity gradient; biomass; photosynthesis; relative growth rate; root to shoot ratio