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Influence of flood-preconditioning and drought on leaf gas exchange and plant water relations in seedlings of pecan
Authors:Michael W. Smith and Susan M. Huslig
Affiliation:

Department of Horticulture and Landscape Architecture, Oklahoma State University, Stillwater, OK 74078, U.S.A.

Abstract:Four-month old seedlings of pecan [Carya illinoensis (Wangenh) C. Koch] were either not flooded or flooded for 14 days, then transferred to well-drained conditions for 23 days. Water was withheld from one-half of the trees for 6 days, then trees were rewatered, and water was withheld from all trees. Leaf expansion, leaf dry weight, and the number of new leaves that developed were reduced by flooding, but not trunk or root dry weights. Evapotranspiration rates of flooded trees after transfer to well-drained conditions were initially higher than those of unflooded trees, but decreased to rates of control trees after 12 days. Flooding had no effect on photosynthesis after trees had been transferred to well-drained conditions for 23 days. Drought-stressed trees with leaf water potentials as low as − 1.93 MPa had lower leaf photosynthetic CO2 assimilation rate (A), transpiration (E), and leaf conductance to CO2 (gL) as compared to wellwatered trees. Leaf internal CO2 concentration (ci) was reduced only by the most severe water-stress treatment. Water use rates and relative water content were lower at the permanent wilting point during a second drought stress when trees had been exposed previously to drought stress.
Keywords:Leaf net photosynthetic rate (A)   transpiration (E)   leaf conductance to CO2 (gL)   leaf internal CO2 concentration (ci)   relative water content (RWC)   leaf water potential (ψL)   leaf osmotic potential (ψs)   leaf turgor potential (ψp)
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