Effects of light and temperature on leaf anatomy and photosynthesis in Fragaria vesca

Abstract

Fragaria vesca, the woodland strawberry, was grown under a series of controlled environments including variations in light intensity, average temperatures, and temperature amplitude around a constant mean. Observations on CO exchange capacities, leaf anatomy, and cell ultrastructure were made for each treatment to determine relationships between these variables. With increasing light intensity, leaf thickness, leaf density, and mesophyll cell surface area and volume per leaf surface area increased. Net photosynthesis (NPS) per leaf weight decreased with increasing light pretreatment while NPS per area increased from low to medium intensity, then decreased at the highest intensity. Depression of photosynthesis at the highest light pretreatment may have been due to massive starch accumulation in the chloroplasts associated with the sodium vapor lamps used. Correlation of all anatomical variables was highly significant with dark respiration and NPS per dry weight but insignificant for NPS per leaf area. In the variable temperature treatments, photosynthetic acclimation occurred with a shift in optimum temperature for NPS in the direction of prevailing growth temperature. Absolute rates were highest at moderate pretreatment temperatures and were reduced by extreme growth temperatures. Thick leaves with low density mesophyll became thinner and more dense with increasing growth temperature corresponding to an increase in maximum net photosynthetic rates. Leaves became thicker and more dense at the highest temperatures, but with an increase in cell damage and indications of changes in metabolic pathways. Highest correlations for gas exchange rates were with specific leaf weight (weight per area). Correlation with other anatomical variables were scattered or insignificant. It was concluded that adaptation to a range of environmental conditions cannot be consistently attributed to changes in mesophyll cell volume or surface area.

Early generation performance of Fragaria species hybrids in crosses with cultivated strawberry

“…The shade species, F. moschata and F. nubicola, had significantly higher LDW and LA and lower SLW compared with F. nilgerrensis, a sun-adapted species and F. vesca, which is adapted to a range of habitats. High SLW in the sun-adapted species is consistent with observations of sun-adapted leaves of F. vesca (Chabot and Chabot 1977). This can be attributed to increased mesophyll cell number and size (Chabot and Chabot 1977), increased accumulation of assimilates in the leaf, and high Rubisco content in the leaf as Rubisco can account for 60% of leaf proteins (Schaffer et al 1986).…”

“…High SLW in the sun-adapted species is consistent with observations of sun-adapted leaves of F. vesca (Chabot and Chabot 1977). This can be attributed to increased mesophyll cell number and size (Chabot and Chabot 1977), increased accumulation of assimilates in the leaf, and high Rubisco content in the leaf as Rubisco can account for 60% of leaf proteins (Schaffer et al 1986). Poor fruit set has been observed in lower-ploidy species as many have dioecious flowers (Darrow 1966).…”

Factors affecting leaf morphology: a case study of Ranunculusnatans C. A. Mey. (Ranunculaceae) in the arid zone of northwest China

“…Due to their considerable natural physiological diversity, leaves of aquatic plants have been used in many studies of morphological variation. Experiments have demonstrated that a switch from aquatic to aerial placement or a transition from aquatic to terrestrial habitat can result in remarkable changes in leaf physiology and appearance (Chabot and Chabot 1977;Cook 1968;Cook and Johnson 1968). Such differences may indeed be adaptive, improving the fitness of the organism under the new habitat conditions (Schlichting and Pigliucci 1998).…”

Optofluidics of plants

“…17 The portion of the light that is not used by photosynthesis is converted to heat and raises the temperature of the liquid in and around the cell leading to water evaporation. 18 The water vapor finds an outlet to the outside through openings in the leaf membrane. These openings are called stomata.…”