Are some strains of subterranean clover (T. subterraneum) highly susceptible to low temperature stress?

Abstract

Two experiments, one with spaced plants and the other with swards, were conducted in a controlled-temperature glasshouse at Perth, Western Australia. Three strains-Phillip Island, CPI 18293 and CPI 68043H-were selected on the basis of field observations of apparent very poor winter growth in rows, and tested against Tallarook as a control. The temperature treatments were 22/17¦ (day/night) and 12/7¦C. In the spaced plant experiment (occupying the first 48 days of growth), temperature and strain effects were highly significant, but there was no indication of a strain x temperature interaction. In the sward experiment (from days 51 to 77) temperature effects were small; and in only one strain, Phillip Island, was the decline in tops growth due to low temperature greater (P< 0.05) than for Tallarook. The experiments failed to provide support for the so-called 'winter dormancy' phenomenon. Possible explanations for the discrepancy between the present findings and the field observations are given.