Photosynthesis, water relations, and leaf morphology of xeric versus mesic Quercus rubra ecotypes in central Pennsylvania in relation to moisture stress

摘要: Differences in photosynthesis and water relations during drought, leaf morphology, were evaluated 1-year-old greenhouse-grown Quercusrubra L. seedlings from neighboring mesic xeric sites central Pennsylvania, U.S.A. Xeric had higher photosynthetic rates stomatal conductance to vapor than well-watered conditions. During a drought cycle, maintained positive net at significantly lower predawn potential relative content. Mesic exhibited greater intrasource variation gas exchange which may be related reduced selection pressure for tolerance characteristics on the site or gene flow adjacent, upslope site. Nonstomatal limitations increased accounted 98% of reduction as both sources approached incipient wilting. less nonstomatal inhibition photosynth...