Abstract
Root‐tip, 1‐cm of Sorghum bicolor (L.) Moench cv SC283, SC574, GP‐10, and Funk G522DR were exposed to calcium (45Ca2+) at pH 5.5 for 2‐hr in the presence of nitrate‐nitrogen (NO3−‐N) or ammonium‐nitrogen (NH4+‐N). Nitrate (0.1 mM) induced significantly increased 45Ca uptake in Funk G522DR, SC283, and GP‐10 while 0.01 mM NO3 −‐N induced significantly increased 45Ca'uptake in SC574, but 45Ca absorption was significantly decreased at 1 mM NO3—N. In the presence of the NH4+ ion, 45Ca uptake was increased up to 8X that of the NH4 +‐N untreated roots. When ammonium chloride (NH4CI) was used, the Cl− tended to induce an increased 45Ca uptake. Cultivar variation was present.