Caringella, Marissa , Bobich, Edward , Ewers, Frank .
Seasonal nighttime transpiration in adults and resprouts of southern California black walnut and coast live oak.
Nighttime transpiration has been reported in many species, but the seasonal patterns, which may provide insight as to the mechanisms and function, have been little studied. We examined day and nighttime transpiration in two species with differing leaf habit, the deciduous southern California black walnut (Juglans californica) and evergreen coast live oak (Quercus agrifolia). For each species two growth forms were examined, adults and 2-year post-fire basal resprouts. Daytime (12pm-4pm) and nighttime (12am-4am) stomatal conductance was measured in order to determine if nighttime transpiration was occurring, and to compare the levels of occurrence between species and growth forms. Results showed consistent nighttime stomatal conductance for both species, although at a greater percentage of the daytime rate in Q. agrifolia. Mean day and nighttime stomatal conductance were also significantly higher in Q. agrifolia (day 89.5 mmol m-2s-1; night 53.5 mmol m-2s-1) as compared to J. californica (day 49.3 mmol m-2s-1; night 22.4 mmol m-2s-1). Within both species the resprouts had greater mean day and nighttime stomatal conductance as compared to the adults. Day and nighttime water potential measurements showed a slight increase in stomatal conductance as leaf water potential increased across both species and growth forms. No correlation was shown between stomatal conductance and percent relative humidity. The level of nighttime stomatal conductance in Q. agrifolia suggests an unseen benefit to nighttime transpiration in this species that outweighs the cost of transpirational water loss even in a water-limited Mediterranean-type climate.
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1 - California State Polytechnic University, Pomona, Biological Sciences, 3801 West Temple Avenue, Pomona, CA, 91768, USA
2 - California State Polytechnic University, Pomona, 3801 W. Temple AVE, Pomona, CA, 91768, USA
3 - California State Polytechnic University, Pomona, Department Of Plant Biology, 3801 West Temple Avenue, Pomona, CA, 91768, USA
Presentation Type: Poster:Posters for Topics
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM