Article by VICTOR A. TIEDJENS
FACTORS AFFECTING ASSIMILATION OF AMMONIUM AND
NITRATE NITROGEN, PARTICULARLY IN
TOMATO AND APPLE
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.