
TY  - JOUR
A1  - Zhang, Hehui 
A1  - Sharifi, MR 
A1  - Nobel, PS 
T1  - Photosynthetic Characteristics of Sun Versus Shade Plants of <I>Encelia farinosa</I> as Affected by Photosynthetic Photon Flux Density, Intercellular CO<sub>2</sub> Concentration, Leaf Water Potential, and Leaf Temperature
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1995
VL  - 22
IS  - 5
SP  - 833
EP  - 841
KW  - 
UR  - https://doi.org/10.1071/PP9950833 
N2  - Limitations to photosynthesis were examined for Encelia farinosa Toney et A.Gray, a common C3 sub-shrub in arid regions of south-westem United States, for plants grown in full sunlight and those shaded to 40% of full sunlight. The initial slopes of CO2 assimilation (A) versus intercellular CO2 concentration curves were similar for sun and shade plants at low photosynthetic photon flux density (PPFD) but higher for sun plants as the PPFD increased, indicating a greater limitation by carboxylation capacity in shade plants. Sun plants had higher electron transport rates but a lower ratio of electron transport capacity to carboxylation capacity (Vmax); the ratio was inversely proportional to mesophyll conductance for both sun and shade plants. Dark respiration decreased with decreasing leaf water potential (&#936;1) in sun plants but remained unchanged in shade plants; day respiration was little affected by PPFD for both sun and shade plants. Stomatal conductance (gs) was similar for sun and shade plants under high soil-moisture conditions but higher in sun plants as &#936;1 decreased; for all data considered together, changes in the leaf-air vapour pressure difference accounted for 71% of the variation in gs. The lower A for shade plants of E. farinosa apparently resulted from a lower Vmax, as well as a lower gs when plants were under water stress. 
ER  -

