Effects of Phosphorus Deficiency on Growth and Metabolism of Black Mustard. Contributions from the Hull Botanical Laboratory 631

Abstract

The effects of P deficiency on black mustard (Brassica nigra) plants grown in sand culture were studied. The first symptom noted was the deeper green color of the leaves. Later plants became decidedly stunted. Leaves were small, and stems thin and short. Tops were stunted more than roots so that the top-root ratio of -P plants was low. Neither chlorosis nor anthocyanin development were prominent symptoms of P deficiency. Minus-P stems were high in reducing sugars and sucrose but contained about the same amt. of starch as +P ones. The accumulation of sugars seemed to be due mainly to a greater leaf-stem ratio, but also partly to a disturbance of protein synthesis at the amide stage. There was a slight accumulation of amides in the -P stems, but they were lower in total N, soluble N, and nitrates than the checks. The % of ammonia was about the same in the stems of the 2 sets. The -P stems were much lower in total P, soluble P and insoluble P, but more of the total P was in the soluble state.