Selection responses of stomatal length and frequency, epidermal ridging, and other leaf characteristics inLolium perennel.‘grasslands ruanui’

Abstract

Selection was made for both extremes of stomatal pore length,stomatal frequency, upper epidermal ridging, mesophyll thickness and mean cell size, and individual leaf dimensions at the seedling stage within Lolium perenne L. ‘Grasslands Ruanuiߣ grown in a controlled environment. Realised heritabilities were calculated for both selection directions from individual selection responses and overall as regressions of mid-parent values on progeny means. Correlated responses to selection for stomatal and mesophyll characteristics were examined. Heritability of stomatal frequency was twice that of pore length and of frequency X length, but for all characteristics responses were large and sufficient to produce significant differences between the lines selected in opposite directions after only one generation. It was concluded from this that considerable additive genetic variation for the characters was present in the initial population. Stomatal frequency responded negatively to selection for stomatal length, but selecting for frequency had no significant effect on stomatal length. Response to selection for frequency X length was based on a response by stomatal frequency. Leaf length, width, and size all showed significant positive correlated responses to selection for a combination of mesophyll cell size and thickness. Recorded rates of leaf appearance did not differ significantly among any of the F₁ selection lines.