COMPARISON OF THE EFFECTS OF NITRATE AND AMMONIUM FORMS OF NITROGEN ON AUXIN CONTENT IN ROOTS AND THE GROWTH OF PLANTS UNDER DIFFERENT TEMPERATURE CONDITIONS

Average root length, root/shoot ratio and auxin content in roots were higher in plants supplied with nitrate rather than ammonium and grown at 18, 21, 24 degrees C. The effects on root length were most pronounc ed at the highest temperatures (21 and 24 degrees C); and the warmer t he temperature, the earlier appearance of the differences in growth ra te between NO3- and NH4-fed plants. A sharp acceleration of root growt h was characteristic of NO3-fed plants grown at 21 and 24 degrees C an d was associated with a temporary increase in auxin concentration meas ured by immunoassay.