Red clover varieties show nitrogen fixing advantage during the early stages of seedling development
2017
Thilakarathna, M.S. | Papadopoulos, Y.A. | Grimmett, M. | Fillmore, S.A.E. | Crouse, M. | Prithiviraj, B.
Plant and environmental factors affect root nitrogen (N) exudation dynamics in legumes. To better understand the genotypic variability and plant factors affecting root N release nodulation, plant growth, tissue N content, and root N exudation, six (three diploid and three tetraploid) red clover (Trifolium pratense L.) varieties were evaluated under controlled environmental conditions during the first 8 wk of plant growth after rhizobia inoculation. Genotypic differences were found for nodulation, plant dry weight (DW), leaf area, root attributes (root length, surface area, volume, and diameter), shoot and root N concentration, and N content. Genotypic differences were also found for root exudate N content in terms of NO₃⁻-N, NH₄⁺-N, and dissolved organic N (DON). In general, root exudate inorganic N content was greater in tetraploid varieties than in the diploids throughout the growth period. Root exudate DON content was greater than the inorganic N content. The NO₃⁻-N content in root exudate was positively correlated with root growth attributes and root N concentration, whereas NH₄⁺-N content was positively correlated with nodule number. Root exudate DON was positively correlated with shoot N concentration and average nodule DW. These results highlight the existence of genotypic differences among red clover varieties for plant morphological factors affecting root N release during the early stages of plant development.
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