Høgh-Jensen, Dr Henning; Schjoerring, Dr Jan K. and Soussana, Dr Jean-Francois (2002) The influence of phosphorus deficiency on growth and nitrogen fixation of white clover plants. Annals of Botany, 90, pp. 745-753.
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The effects of P deficiency on growth, N2-fixation and photosynthesis in white clover (Trifolium repens L.) were investigated using three contrasting relative addition rates of P, or following abrupt withdrawal of the P supply. Responses to a constant below-optimum P supply rate consisted of a decline in N2-fixation per unit root weight and a small reduction in the efficiency with which electrons were allocated to the reduction of N2 in the nodules. Abrupt P removal arrested nodule growth and caused a substantial decline in nitrogenase activity per unit root weight, but not per unit nodule mass.
Similarly, the rate of photosynthesis per unit leaf area was unaffected by abrupt P removal, while the CO2 acquisition for the plant as a whole decreased due to a decline in total leaf area, leaf area per unit leaf weight and utilisation of incoming radiation. These changes followed the decline in tissue P concentrations. The ratio between CO2-fixation and N2-fixation was maintained under short-term P deprivation but increased under long-term low P supply indicating a down-regulation of nodule activity following morphological and growth adjustments. It is concluded that N2-fixation does not limit the growth of clover plants experiencing P deficiency. A low P status induces changes in the relative growth of roots, nodules, and shoots rather than changes in N and/or C uptake rates per unit mass or area of these organs.
|EPrint Type:||Journal paper|
|Keywords:||fodder legumes, phosphorus, phosphorus deficiency, N2-fixation, nitrogenase activity, white clover, Trifolium repens|
|Subjects:||Crop husbandry > Production systems > Pasture and forage crops|
|Research affiliation:||Denmark > DARCOF I (1996-2001) > I.2 Nitrogen fixation, recycling and leaching in organic cropping systems|
|Deposited By:||Jensen, Dr Henning Høgh|
|Deposited On:||20 Dec 2002|
|Last Modified:||12 Apr 2010 07:27|
|Refereed:||Peer-reviewed and accepted|
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