Effects of solution pH, temperature, nitrate/ammonium ratios, and inhibitors on ammonium and nitrate uptake by Arabica coffee in short-term solution culture
Solution pH, temperature, nitrate (NO3-)/ammonium (NH4+) ratios, and inhibitors effects on the NO3- and NH4+ uptake rates of coffee (#Coffea arabica# L.) roots were investigated in short-term solution culture. At intermediate pH values (4.25 to 5.75) typical of coffee soils, NH4+ and NO3- uptake rates were similar and nearly independent of pH. Nitrate uptake varied more with temperature than did ammonium. Nitrate uptake increased from 0.05 to 1.01 micromol/g FW/h between 4 and 16°C, and increased three-fold between 16 to 22°C. Between 4 to 22°C, NH4+ uptake rate increased more gradually from 1.00 to 3.25 micromol/g FW/h. In the 22-40°C temperature range, NH4+ and NO3- uptake rates were similar (averaging 3.65 and 3.56 micromol/g FW/h, respectively). At concentrations ranging from 0.5 to 3 mM, NO3- did not influence NH4+ uptake rate. However, NO3- uptake was significantly reduced when NH4+ was present at 3 mM concentration. Most importantly, total uptake(NO3- + NH4+) at any NO3-/NH4+ ratio was higher than that of plants fed solely with either NH4+ or NO3-. Anaerobic conditions reduced NO3- and NH4+ uptake rate by 50 and 30%, respectively, whereas dinitrophenol almost completely inhibited both NH4+ and NO3- uptake. These results suggest that Arabica coffee is well adapted to acidic soil conditions and can utilize the seasonally prevalent forms of inorganic N. These observations can help optimizing coffee N nutrition by recommending cultural practices maintaining roots in the temperature range optimum for both NH4+ and NO3- uptake, and by advising N fertilization resulting in a balanced soil inorganic N availability.
| Main Authors: | , , |
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| Format: | article biblioteca |
| Language: | eng |
| Subjects: | F61 - Physiologie végétale - Nutrition, Coffea arabica, racine, absorption de substances nutritives, azote, nitrate, ammoniac, culture hydroponique, facteur du milieu, pH, température, anaérobiose, http://aims.fao.org/aos/agrovoc/c_1721, http://aims.fao.org/aos/agrovoc/c_6651, http://aims.fao.org/aos/agrovoc/c_5273, http://aims.fao.org/aos/agrovoc/c_5192, http://aims.fao.org/aos/agrovoc/c_5187, http://aims.fao.org/aos/agrovoc/c_349, http://aims.fao.org/aos/agrovoc/c_3734, http://aims.fao.org/aos/agrovoc/c_2594, http://aims.fao.org/aos/agrovoc/c_5753, http://aims.fao.org/aos/agrovoc/c_7657, http://aims.fao.org/aos/agrovoc/c_23990, |
| Online Access: | http://agritrop.cirad.fr/390298/ http://agritrop.cirad.fr/390298/1/390298.pdf |
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