INFLUENCE OF AMMONIUM-NITRATE RATIOS ON THE GROWTH AND NITROGEN UPTAKE OF PEARL-MILLET

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a potentially high-yielding grain crop for the Southern Coastal Plain region of the USA. Information on the growth and N nutrition of pearl millet is limited therefore, this study was initiated with the objective of studying pearl millet growth, N content, N uptake patterns and N-form preference. Plants were grown in solution culture using a modified Hoagland's solution. Solutions were changed weekly and transpirational losses replaced daily. The N-form ratios were 1:0, 3:1, 1:1, 1:3 and 0:1 NH4+ to NO3-. Uptake was determined by difference between the initial and final solutions. Nitrate and NH4+ uptake patterns were different from each other and were influenced by the ratio of NH4+ to NO3-. After the plants had been transferred to the solutions, ammonium was preferred for the first two weeks, with NO3- preferred thereafter. Nitrate uptake was highest during the grain filling period. Plant growth as measured by leaf, stem, root, and seed weight, plant height, average seed weight, and head length was generally reduced as NH4+ increased. The largest reduction was. © 1990, Taylor & Francis Group, LLC. All rights reserved.