Effects of temperature and osmotic stress on leaf appearance rate

Plant leaf regrowth stage is widely accepted as the key determinant for grazing interval, however regular monitoring and assessment of leaf appearance rate on farm is often neglected due to time and ambiguity in assessment. Ambient temperature and soil moisture availability are two of the principle factors determining the production and morphology of temperate pasture species. A controlled glasshouse study in which differing moisture stress treatments were applied at different ambient temperatures via a hydroponic culture system, showed that leaf appearance rate of perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) can be successfully estimated using a linear regression model. The model produced from the glasshouse study was evaluated and further developed using historical leaf appearance rate data collated on farm over three years. A simple decision support tool was subsequently developed to quantify the expected leaf appearance rate of these species over the range of ambient temperature and soil moistures that are experienced in the temperate environment.