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Einfluß des Lichtangebotes auf das Wachstum und die biologische Stickstoff‐Fixierung von Weißklee ( Trifolium repens L.)
Author(s) -
Kessler W.,
Boller B. C.,
Nösberger J.
Publication year - 1988
Publication title -
journal of agronomy and crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.095
H-Index - 74
eISSN - 1439-037X
pISSN - 0931-2250
DOI - 10.1111/j.1439-037x.1988.tb00326.x
Subject(s) - nitrogenase , trifolium repens , nitrogen fixation , photoperiodism , chemistry , nitrogen , horticulture , nitrate , photosynthesis , zoology , dry weight , botany , biology , organic chemistry
Influence of light quantity on growth and biological nitrogen fixation of white clover ( Trifolium repens L.) The influence of photon irradiance (E p ; 100 to 500 μmol m −2 s −1 ) and of the photoperiod (16 or 11 h) on growth and nitrogenase activity of nodulated white clover plants was studied in growth chambers at two nitrate levels (1.0 and 7.5 mM NO 3 − ). Total dry mass production, the root proportion and nitrogenase activity increased with increasing E p and photoperiod. Nitrogenase activity generally increased proportionally to root mass. Only at low E p (100 μmol m −2 s −1 ) and under a short photoperiod (11 h) was the specific nitrogenase activity per unit root mass reduced. An abrupt change in E p led to a rapid and parallel change in nitrogenase activity and relative growth rate. A higher NO 3 − concentration in the nutrient solution (7.5 mM) led to a marked decrease in specific nitrogenase activity, but increased growth between 200 and 500 μmol m −2 s −1 during early development only. At 100 μmol m −2 s −1 , there was no growth response to nitrate, although its effect on nitrogenase activity was more marked than at a higher E p . The results show that with changing light quantity, biological nitrogen fixation of white clover adapts to the existing demand for nitrogen and does not limit growth except during early development, even when light supply is low.