Winter temperatures and reproductive development affect the productivity and growth components of white clover and phalaris growing in a mixed pasture

Abstract

The effects of low winter temperatures (means down to 5�C, daily air minimums to 3�C and 82 potential frost days), frost damage and reproductive development on productivity and growth components of white clover ( Trifolium repens cv. Haifa) and phalaris (Phalaris aquatica cv. Australian Commercial) growing together in a mixed pasture were studied during winter and spring. Initially there was a higher proportion of white clover in the pasture which was maintained throughout winter and early spring. Leaf appearance rates were similar for both species, but petiole extension rates of white clover were significantly less than leaf extension rates of phalaris. Growth rates were higher per tiller for phalaris than per stolon for white clover. Larger sward yields of white clover were only maintained because of the higher density of white clover growing points. The lower extension rates of white clover were due to a different temperature response curve to phalaris. Below 10�C there was little growth of white clover leaves whereas phalaris had some leaf growth down to below 5�C. There was evidence that leaf extension rates of both white clover and phalaris were stimulated by reproductive development. This had a larger effect on phalaris, but also resulted in greater susceptibility to frost damage, though the damage to phalaris was not enough to reduce leaf growth to the same level as white clover. Leaf damage from frost/low temperatures was generally marginal.