Studies in the nutrition of the forage legumes

Summary The effect has been studied of varying levels of copper supply on the copper, iron and manganese contents of plants ofT. subterraneum in which the growth rate had been altered by variation in nitrate supply and light intensity.It has been found that the copper content of the plants is related logarithmically to the level of copper in the nutrient and is not affected by nitrate supply or intensity of illumination. Within the limits set, there is no change in the copper content of the tops with time, but the concentration in the roots shows a progressive increase, particularly at the higher levels of copper supply. Between one-fifth and one-quarter of the copper present in the roots is in the free space.The concentration of both iron and manganese decline with increase in copper supply. Although this is largely an indirect result arising from increased growth at the higher copper supply, a considerable distortion of the Fe/Mn ratio can occur. In the roots, however, there appears to be a direct restrictive effect of the higher copper supply on manganese concentration, over and above the indirect effect of growth dilution.The data on which this paper is based are mainly from the these submitted by M. G. Yates, P. E. Cansfield and J. T. Saul for the degree of Ph.D. of the University of Nottingham.