Studies on the nutrition of pasture plants in the South-west of Western Australia. IV The Growth of Subterranueum Clover (Trifolium subterraneum L.) as affected by lime, molybdenum, and Potassium

Abstract

The results of a pot-culture experiment in which subterranean clover was grown on a coarse siliceous sand slightly acid in reaction are presented. Maximum yields resulted from application of potassium, together with either molybdenum or lime. The lime X molybdenum interaction was almost always negative, but its magnitude varied with time and potassium: in the absence of potassium it diminished in magnitude, but increased markedly in its presence. The lime X potassium and molybdenum X potassium interactions were strongly positive during the later stages of growth, but only in the absence of molybdenum and lime respectively. The effects of treatment on leaf-weight and leaf-area ratio were not closely related to those on relative growth rate. The latter were determined primarily by treatment effects on net assimilation rate. Both relative growth rate and net assimilation rate were increased by potassium. The results provide further support for the findings of Anderson and Oertel (1946) that, in legumes, nitrogen is the primary nutrient concerned in the response to lime and molybdenum, and that the molybdenum concentration gives little indication of the minimum requirements for satisfactory growth. The possible effect of lime on the transport of molybdenum from roots to tops is discussed.