Photosynthetic-respiratory Responses of ‘Merion’ Kentucky Bluegrass and ‘Pennlawn’ Red Fescue at Reduced Light Intensities
1975
Wilkinson, J. F. | Beard, J. B. | Krans, Jeff
The objectives were to characterize the photosynthetic-respiratory responses of Kentucky bluegrass (Poa pratensis L. ‘Merion’) and red fescue (Festuca rubra L. ‘Pennlawn’) to reduced light intensities. Merion and Pennlawn were grown in separate growth chambers at light intensities of 2.7, 10.8, and 43 klux. Light quality, soil moisture, and soil temperature were standardized among chambers. Infrared CO₂ analysis was used to measure assimilation rates, light saturation levels, and light compensation points of both swards and individual plants. Both species had decreased net photosynthesis (PN) and dark respiration (RD), lower light saturation levels, and decreased light compensation points under reduced light intensity. Swards generally had lower PN and RD rates but higher light saturation levels and light compensation points than individual plants. Both species responded similarly to reduced light intensity in terms of PN, light saturation levels, and light compensation points. These factors could not be associated with the ability of Pennlawn to provide a more desirable turf than Merion in the shade. RD of individual plants of Pennlawn was reduced at the lowest light intensity, whereas the RD of Merion was not. This response may contribute to the positive CO₂ balance of Pennlawn at reduced light intensities and thus to its shade adaptability.
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