Morphogenetic adaptation to defoliation and soil fertility in perennial ryegrass (lolium perenne)

Abstract

Morphogenetic adaptation, plasticity, and mortality of four perennial ryegrass populations, representing different selection histories, were compared in response to soil fertility and to defoliation severity. In a second experiment, morphogenetic adaptation and plasticity in response to defoliation frequency were studied in two divergent sub-populations. Genetic variability was found between ryegrass populations for leaf appearance and elongation rates, leaf size, and tiller number. All populations exhibited plasticity in response to defoliation severity and soil fertility. There was no genetic variation for plasticity, the morphological response to the environment. Morphogenetic differences between populations remained constant across environments and resulted in differential mortality under the most severe defoliation. Both leaf length and rate of leaf appearance were positively correlated with greater mortality. The ryegrass ideotype for hill country is a compromise between yield and persistence. © 2001 Taylor & Francis Group, LLC.