Responses to CO2 Enrichment by Two Genotypes of Arabidopsis thaliana Differing in their Sensitivity to Nutrient Availability

The responses of two genotypes of Arabidopsis thaliana, whichdiffer in their sensitivities to nutrients to present and predictedfuture CO₂ concentration were determined under rich vs. poornutrient regimes on the basis of both single traits and thewhole plant. Based on individual traits, the two genotypes respondedsimilarly to CO₂ enrichment for all the traits measured exceptfor rate of increase in crown diameter, for which a decreasewas observed in the less nutrient-sensitive genotype grown atincreased CO₂. Based on the overall response of the whole plant,by analysing groups of plant traits using multivariate analysis,the two genotypes differed substantially from one another andboth responded more strongly to nutrient availability than toCO₂ concentration, especially for traits measured at harvestthat related to reproductive fitness. The less nutrient-sensitivegenotype also showed a weaker overall response to CO₂, and thepattern of the overall response was strikingly similar at differentnutrient supply. In contrast, the more nutrient-sensitive genotyperesponded more strongly to CO₂ than the less nutrient-sensitivegenotype, and responded differently to CO₂ at low vs. high nutrientavailability.Copyright 1995, 1999 Academic Press Plasticity, CO₂ enrichment, nutrient status, nutrient x CO₂ interaction, Arabidopsis thaliana, canonical analysis