FACTORS AFFECTING ASSIMILATION OF AMMONIUM AND NITRATE NITROGEN, PARTICULARLY IN TOMATO AND APPLE

Abstract

Plants absorb ammonium and nitrate nitrogen in varying quantities, depending partly on the rate of assimilation2 of either ion in the plant. That certain specific conditions are necessary for the most efficient assimilation of either form of nitrogen has been pointed out (40) . Different species vary in the efficiency with which they utilize the nitrate or ammonium ion under a given set of conditions (29). The hypothesis that both ions probably are finally utilized as ammonium, even though external requirements may be different, involves an interesting study, a preliminary report of which has been published (40). A continuation of these studies has established certain relationships affecting the assimilation of nitrate and ammonium nitrogen. Such factors as hydrogen-ion concentration and available carbohydrates have a direct bearing on the assimilatory processes. That these relationships vary with the source of nitrogen, and that the location of the initial assimilatory processes varies with the type of plant, will be pointed out. Experimental methods