caa a22 4500 397522398 CHVBK 20180308164636.0 cr unu---uuuuu 161202e199503 xx s 000 0 eng 10.1093/jxb/46.3.285 doi (NATIONALLICENCE)oxford-10.1093/jxb/46.3.285 The effect of waterlogging on nitrogen fixation and nodule morphology in soil-grown white clover (Trifolium repens L.) [Elektronische Daten] [Ruth Pugh, John F. Witty, Lance R. Mytton, Frank R. Minchin] Nodulated, pot-grown plants of white clover (Trifolium repens cv. Katrina) were subjected to different soil moisture regimes and the effect of these treatments on dry matter production, nitrogenase activity, aerenchyma formation, and bacteroid distribution was determined. In the first experiment, after 9 weeks growth shoots were significantly (P<0.01) heavier for clover plants which were flooded from germination compared with those subjected to normal watering, indicating that clover can adapt to long-term waterlogging. In the second experiment, time-courses of acetylene reduction showed a lag phase of only 10 min for waterlogged plants, suggesting that gas exchange was occurring through aeration pathways rather than the water. Flooded plants that were drained 24 h prior to acetylene reduction assays had substantially greater nitrogenase activity than normally watered or continually flooded plants. However, there was a marked decrease in nitrogenase activity when plants which had been watered normally were flooded, suggesting a sensitivity of white clover to sudden changes in moisture conditions. Morphological studies of nodules from plants grown in normally watered and continually flooded soil showed increased aerenchyma production around roots and nodules of waterlogged plants. In addition, the infected cells of submerged nodules were larger and had larger vacuoles than those from nodules of normally watered plants. This increase in vacuole volume to protoplast volume in infected cells may play a role in the tolerance of white clover nodules to waterlogging. © Oxford University Press Research Papers nationallicence White clover nationallicence waterlogging nationallicence hypoxia nationallicence nitrogen fixation nationallicence root nodule morphology nationallicence Pugh Ruth Department of Environmental Biology, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Dyfed SY23 3EB, UK aut Witty John F. Department of Environmental Biology, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Dyfed SY23 3EB, UK aut Mytton Lance R. Department of Environmental Biology, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Dyfed SY23 3EB, UK aut Minchin Frank R. Department of Environmental Biology, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Dyfed SY23 3EB, UK aut Journal of Experimental Botany Oxford University Press 46/3(1995-03), 285-290 0022-0957 46:3<285 1995 46 exbotj https://doi.org/10.1093/jxb/46.3.285 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jxb/46.3.285 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pugh Ruth Department of Environmental Biology, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Dyfed SY23 3EB, UK aut NATIONALLICENCE 700 1- Witty John F. Department of Environmental Biology, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Dyfed SY23 3EB, UK aut NATIONALLICENCE 700 1- Mytton Lance R. Department of Environmental Biology, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Dyfed SY23 3EB, UK aut NATIONALLICENCE 700 1- Minchin Frank R. Department of Environmental Biology, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Dyfed SY23 3EB, UK aut NATIONALLICENCE 773 0- Journal of Experimental Botany Oxford University Press 46/3(1995-03), 285-290 0022-0957 46:3<285 1995 46 exbotj Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford