Journal Article

Ecotypic variation in growth responses to simulated herbivory: trade-off between maximum relative growth rate and tolerance to defoliation in an annual plant

Iván D. Camargo, Rosalinda Tapia-López and Juan Núñez-Farfán

in AoB PLANTS

Published on behalf of Annals of Botany Company

Volume 7, issue
Published online March 2015 | e-ISSN: 2041-2851 | DOI: http://dx.doi.org/10.1093/aobpla/plv015

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It has been hypothesized that slow-growing plants are more likely to maximize above-ground biomass and fitness when defoliated by herbivores than those with an already high relative growth rate (RGR). Some populations of the annual herb Datura stramonium L. can tolerate foliar damage better than others. The physiological basis of this difference is examined here in a comparative study of two ecotypes that differ in tolerance and maximum growth rate, using a growth analytical approach. One hundred and fifty-four plants of each ecotype grown under controlled conditions were suddenly defoliated (35 % of total leaf area removed) and a similar sample size of plants remained undefoliated (control). Ontogenetic plastic changes in RGR and its growth components [net assimilation rate (NAR), specific leaf area and leaf weight ratio (LWR)] after defoliation were measured to determine whether these plastic changes maximize plant growth and fitness. Different ontogenetic phases of the response were discerned and increased RGR of defoliated plants was detected at the end of the experimental period, but brought about by a different growth component (NAR or LWR) in each ecotype. These changes in RGR are putatively related to increases in fitness in defoliated environments. At the intra-specific scale, data showed a trade-off between the ability to grow under benign environmental conditions and the ability to tolerate resource limitation due to defoliation.

Keywords: Datura stramonium; defoliation tolerance; growth response coefficients; net assimilation rate; ontogenetic plasticity response to defoliation; plant relative growth rate

Journal Article.  8431 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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