Author
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Sinclair, Thomas |
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VADEZ, V. - UNIVERSITY OF FLORIDA |
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Submitted to: Plant and Soil
Publication Type: Review Article Publication Acceptance Date: 7/25/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Due to economic or environmental limitations many crops in the world must be grown on soils with low nitrogen (N) and/or phosphorus (P) availability. This review, coauthored by an USDA, ARS scientist at Gainesville, FL, considers concepts for altering the physiology of plants to allow increased crop productivity on nutrient-limited soils. An underlying fact, however, is that both N and P are essential in many of the biochemical activities of the plant, including a requisite minimum concentration of these elements in the seed. As a result, increased amounts of both elements must be acquired by the plants to achieve increased crop yields. Plants are well adapted to recover N and P from the soil solution even at low concentrations. The key approach for dealing with low N soil is to increase the use of biological fixation of atmospheric N2. In particular, legumes can be used directly as producers of grain or indirectly as the source of fixed N for other crops. Phosphorus uptake can be improved by releasing unavailable P in the soil into the soil solution. From a plant perspective, specific compounds could be excreted from the roots into the soil at sufficient quantities to recover previously unavailable P. Technical Abstract: Nitrogen and phosphorus are recognized as essential elements in crop production but the full extent of the requirement for these elements in the physiological processes leading to crop growth is not always fully appreciated. Virtually all biochemical compounds in plants that support development and growth contain N and/or P. Deficiencies in either element lead to a lost ability for plant growth such that there is a quantitative relationship between the accumulation of each of these elements and crop yield. Few options appear to exist to greatly diminish the requirement for either element. Consequently, crop yields cannot be increased without increased acquisition of N and P by plants. While little opportunity exists to increase N recovery under low nutrient environments, several options can be investigated for increasing P accumulation by the crop. However, the rigid limitation of N on yields means that without an external N supply, biological N2 fixation must be enhanced to increase N input. In particular, research needs to be focused on whole-plant processes in legumes that lead to enhanced symbiotic N2 fixation. A critical aspect of increased legume production will be improved management of P to allow legumes to achieve high N2 fixation rates. |
