Ecophysiology of Two Solar-Tracking Desert Winter Annuals. I. Photosynthetic Acclimation to Growth Temperature

Abstract

The ability of two solar-tracking desert winter annuals, Lupinus arizonicus Watson and Malvastrum rotundifolium Gray, to acclimate their photosynthetic characteristics to different growth temperatures was examined. Plants were grown in growth chambers under 25/15°C and 40/30°C thermal regimes. The plants grown at 40/30°C were also subjected to a drying cycle in order to assess whether or not drought affected the photosynthetic acclimation to high temperatures. Both species exhibited shifts in their temperature optima and thermal death points for photosynthesis. The droughted plants showed no further acclimation than did the watered plants grown at 40/30°C. Using representative meteorological conditions measured in Death Valley, California, it was predicted that photosynthetic acclimation plays only a small role in enhancing daily carbon-gaining ability for late-season conditions. However, under conditions of drought stress and high temperatures, the acclimation may prevent thermal death and extend plant life.

Comparison of temperate and tropical rainforest tree species: photosynthetic responses to growth temperature

“…Forseth and Ehleringer 1982;Vallejos and Pearcy 1987). In the rainforest species of this study, the highest rates of net photosynthesis at extreme temperatures were shown in leaves grown under moderate temperatures.…”

Tolerance of Photosynthesis to High Temperature in Desert Plants

“…This suggests that the acclimation response of these cool season plants may be related to a benefit of having a low thermal stability during the cool portion of their growing season. Other studies (2,5,9,12) have shown that photosynthetic rates at cool temperatures (15-25°C) generally fall significantly when plants acclimate to increased temperature. The ability to acclimate to a low thermal stability could, thus, be a requirement for the high rates of photosynthesis characteristic of the winter annuals during the early part of their growing season (8,19).…”

“…Previous attempts to analyze the benefit of acclimation have considered the differential effect of the acclimation response on carbon gain by the plants during the warm season (5,7). These analyses generally show very little benefit (and in one case a disadvantage [7]) of the acclimation response.…”

Seasonal Acclimation of Stem Photosynthesis in Woody Legume Species from the Mojave and Sonoran Deserts of California

“…Are these seasonal changes in stem Pn adapltive by analogy with that found in leaves of desert species? Severa1 studies have demonstrated seasonal shifts in the thermal optimum for leaves of desert species (Strain and Chase, 1966;Pearcy, 1977;Berry and Bjorkman, 1980;Badger et al, 1982;Forseth and Ehleringer, 1982). For example, the thermal optimum of leaf Pn for L. tridenfata iiicreased by 10°C (35-45OC) between the spring and summer (Mooney et al, 1977).…”