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 pronounced at the highest temperatures (21 and 24 degrees C); and the warmer the temperature, the earlier appearance of the differences in growth rate between NO3- and NH4-fed plants. A sharp acceleration of root growth was characteristic of NO3-fed plants grown at 21 and 24 degrees C and was associated with a temporary increase in auxin concentration measured by immunoassay.