Forms and Levels of N on Growth and Nutrition of Cacao.
(S04-baligar293539-poster)
Authors:
V.C. Baligar* - USDA-ARS-ACSL-BARC-W J.A. Bunce - USDA-ARS-ACSL-BARC-W E.A. Johnson - USDA-ARS-ACSL-BARC-W R.C. Sicher - USDA-ARS-ACSL-BARC-W B.A. Bailey - USDA-ARS-ACSL-BARC-W
Abstract:
Ammonium and nitrate are the major forms of N present in tropical soils. A climatically controlled growth chamber was used to assess the influence of forms (nitrate, ammonium and mix of
nitrate+ammonium) and levels (1.5 to 12.0 mM) of N on the growth and concentration of
macronutrients of cacao. Plants were grown in 1 gal. containers of vermiculite and exposed 14 hours to 350 ìmoles/s/m squre light intensity at 30 degree C and 75% RH. At harvest, growth parameters were measured, shoot samples were analyzed for nutrient content. Growth parameters and macro-nutrient concentrations of cacao varied depending on the form and level of N. Increasing nitrate-N from 1.5 to 6.0 mM and ammonium-N from 1.5 to 9 mM increased the growth parameters. In mixed N treatment, growth parameters increased with increasing N up to 3.0 mM of nitrate-N. However, there was decline in growth at 6.0 mM nitrate, but further increases in N increased the growth parameters. Irrespective of forms of N, increasing levels of N increased the concentration of N and S. Forms and levels of N had no effect on concentrations of Ca and Na. Concentrations of K and Mg increased with increasing levels of nitrate-N and decreased with increasing levels of ammonium and mixed N. Levels of N had no effect on P concentration, however P concentrations were higher for nitrate-N and mixed N. Based on these results it appears that higher levels of N, irrespective of its form, are toxic to cacao.
Speaker Information: Virupax Baligar, USDA-ARS-ACSL-BARC-W, Bldg. 001, Room 342,10300 Baltimore Avenue, Beltsville, MD 20705-2350; Phone: 301-504-6492; E-mail: [email protected]
Session Information: Monday, November 3, 2003, 4:00 PM-6:00 PM Presentation Start: 4:00 PM (Poster Board Number: 1221) Keywords: Cacao; Nitrate; Ammonia; Shoot and Root Mineral Nutrition
