Nutrient absorption by pea plants during dinitrogen fixation. 1. Comparison with nitrate nutrition.

In experiments with pea cv. Rondo grown hydroponically for 6 wk with nitrate as the only N source, an acidic nutrient uptake pattern was observed. When effectively nodulated plants were fixing nitrogen, however, cation absorption exceeded anion absorption resulting in an alkaline ion uptake pattern. Maintaining ambient temp. at 13 deg C allowed for comparison of the effects of N acquisition on nutrient absorption and proton or hydroxyl/bicarbonate excretion by the roots in plants with similar DM yield and N content.The amount of excreted alkalinity or acidity for both nitrate-supplied and nitrogen-fixing plants corresponded well with the respective excess absorption of nutritive anions or cations. Physiological and agronomic consequences of the alkaline nutrient uptake pattern and acidity generation by nitrogen-fixing legumes are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)