The effect of temperature on germination and seedling growth of temperate perennial pasture legumes.

Abstract

Germination of 10 perennial pasture legumes, white clover, red clover, strawberry clover, lucerne, Caucasian clover, cicer milkvetch, crownvetch, birdsfoot trefoil, big trefoil and sericea lespedeza, was compared under five day/night temperature regimens: 24/20, 20/15, 15/10, 12/6 and 8/2¦C. Growth of seedlings of Caucasian clover, birdsfoot trefoil, cicer milkvetch, crownvetch and sericea lespedeza was compared with that of white clover at four serial harvests over a 5-week period at the three highest temperatures. Three main patterns of germination were observed. Firstly, temperature had little effect on maximum percentage, time to first germination and rate of germination in lucerne. Secondly, all Trifolium species and birdsfoot trefoil exhibited reductions in rate of germination and increases in time to germination at the two lowest temperatures. Thirdly, the remaining species showed either very slow or no germination at the two lowest temperatures, where there were large reductions in the maximum germination where germination occurred. Seedling growth was characterized by better dry matter and leaf production from white and Caucasian clovers at 15/10¦C than for the other species, but very marked increases in growth at the higher temperatures by the other four species. Lespedeza was always the least vigorous seedling, and birdsfoot trefoil and crownvetch grew as well or better than the Trifolium species at 24/20¦C. Slow first leaf appearance in crownvetch and cicer milkvetch seemed to be associated with a much greater capacity for cotyledon expansion in these species. While Caucasian clover appears to be well suited for establishment under Australian conditions, promising species such as cicer milkvetch and crownvetch will require selection for better germination and seedling growth at low temperatures or the introduction of more winter active germplasm if they are to become useful plants in Australian pastures.