Acclimation of Photosynthetic Activity of Zantedeschia `Best Gold' in Response to Temperature and Photosynthetic Photon Flux

Photosynthetic activity of individual leaves of Zantedeschia Spreng. `Best Gold' aff. Z. pentlandii (Wats.) Wittm. [syn. Richardia pentlandii Wats.] (`Best Gold'), were quantified with leaf expansion and diurnally, under a range of temperature and photosynthetic photon flux ( PPF ) regimes. Predictive models incorporating PPF , day temperature, and percentage leaf area expansion accounted for 78% and 81% of variation in net photosynthetic rate (P n ) before, and postattainment of, 75% maximum leaf area, respectively. Minimal changes in P n occurred during the photoperiod when environmental conditions were stable. Maximum P n (10.9μmol·m -2 ·s -1 or 13.3 μmol·g -1 ·s -1 ) occurred for plants grown under high PPF (694 μmol·m -2 ·s -1 ) and day temperature (28 °C). Acclimation of P n was less than complete, with any gain through a greater light-saturated photosynthetic rate (P max ) at high PPF also resulting in a reduction in quantum yield. Similarly, any gain in acclimation through increased quantum yield under low PPF occurred concurrently with reduced P max . It was concluded that Zantedeschia `Best Gold' is a shade tolerant selection, adapted to optimize photosynthetic rate under the climate of its natural habitat, by not having obligate adaptation to sun or shade habitats.