Theme 01: Ecophysiology of Grasslands
Description
The purpose of this paper is to establish photosynthetic light response curves for Tanzania grass (Panicum maximum Jacq.) under four leaf temperature levels. Photosynthetic rate was measured as a response to levels of photosynthetic photon flux density (PPFD) on the youngest fully expanded leaves of 12 representative tillers with an infra red gas analyzer. The effect of PPFD was tested for each leaf temperature level in a randomized complete block design. Photosynthetic light response curves were adjusted for each leaf temperature using a non-linear hyperbolic model. The maximum photosynthetic response was 25,59; 31,43; 34,57 and 27,53 µmol CO2 m-2 s-1 for 25, 30, 35 and 40 oC of leaf temperature, respectively. Although light saturation was not attained, response to light increments declined with light levels higher than 1000 – 2000 µmol photon m-2 s-1, and the response curve approximated saturation slowly. Photosynthetic rates of Tanzania grass depend on light and temperature level and these must be considered when modelling crop yield potential.
Included in
Photosynthetic Light Response of Tanzania Grass under Four Levels of Leaf Temperature
The purpose of this paper is to establish photosynthetic light response curves for Tanzania grass (Panicum maximum Jacq.) under four leaf temperature levels. Photosynthetic rate was measured as a response to levels of photosynthetic photon flux density (PPFD) on the youngest fully expanded leaves of 12 representative tillers with an infra red gas analyzer. The effect of PPFD was tested for each leaf temperature level in a randomized complete block design. Photosynthetic light response curves were adjusted for each leaf temperature using a non-linear hyperbolic model. The maximum photosynthetic response was 25,59; 31,43; 34,57 and 27,53 µmol CO2 m-2 s-1 for 25, 30, 35 and 40 oC of leaf temperature, respectively. Although light saturation was not attained, response to light increments declined with light levels higher than 1000 – 2000 µmol photon m-2 s-1, and the response curve approximated saturation slowly. Photosynthetic rates of Tanzania grass depend on light and temperature level and these must be considered when modelling crop yield potential.
