Leaf ontogeny strongly influences photosynthetic tolerance to drought and high temperature in Gossypium hirsutum.
Temperature and drought are major abiotic limitations to crop productivity worldwide. While abiotic stress physiology research has focused primarily on fully expanded leaves, no studies have investigated photosynthetic tolerance to concurrent drought and high temperature during leaf ontogeny. To address this, Gossypium hirsutum plants were exposed to five irrigation treatments, and two different leaf stages were sampled on three dates during an abnormally dry summer. Early in the growing season, ontogenic PSII heat tolerance differences were observed. Photosystem II was more thermotolerant in young leaves than mature leaves. Later in the growing season, no decline in young leaf net photosynthesis (PN) was observed as leaf temperature increased from 31 to 37°C, as average midday leaf water potential (ΨMD) declined from -1.25 to -2.03MPa. In contrast, mature leaf PNdeclined 66% under the same conditions. Stomatal conductance (gs) accounted for 84-98% of variability in leaf temperature, and gswas strongly associated with ΨMDin mature leaves but not in young leaves. We conclude that young leaves are more photosynthetically tolerant to heat and drought than mature leaves. Elucidating the mechanisms causing these ontogenic differences will likely help mitigate the negative impacts of abiotic stress in the future.
Delta Research and Extension Center, Plant and Soil Sciences, Mississippi State University, P.O. Box 197, Stoneville, MS 38776, USA. Electronic address: daryl.chastain@msstate.edu.
Daryl R
DR
Chastain
Department of Crop and Soil Sciences, University of Georgia, 115 Coastal Way, Tifton, GA 31794, USA.
John L
JL
Snider
Department of Biology, University of Central Arkansas, 201 Donaghey, Conway, AR 72035, USA.
John S
JS
Choinski
Department of Crop Science, North Carolina State University, Upper Coastal Plains Research Station, 2811 Nobles Mill Pond Road, Rocky Mount, NC 27801, USA.
Guy D
GD
Collins
College of Agriculture and Environmental Sciences, University of Georgia, 8207 Georgia 37, Camilla, GA 31730, USA.
Calvin D
CD
Perry
Department of Crop and Soil Sciences, University of Georgia, P.O. Box 8112, GSU Statesboro, GA 30460, USA.
Jared
J
Whitaker
Department of Crop and Soil Sciences, University of Georgia, 115 Coastal Way, Tifton, GA 31794, USA.
Timothy L
TL
Grey
United States Department of Agriculture, Agricultural Research Service, National Peanut Research Laboratory, P.O. Box 509, Dawson, GA 39842, USA.
Ronald B
RB
Sorensen
Department of Horticulture, University of Georgia, Athens, GA 30602, USA.
Marc
M
van Iersel
Texas A&M AgriLife Extension, Lubbock, TX 79403, USA.
Seth A
SA
Byrd
Department of Crop and Soil Sciences, University of Georgia, 115 Coastal Way, Tifton, GA 31794, USA.
Wesley
W
Porter
D002734:Chlorophyll / Q000378:metabolism; D055864:Droughts; D003368:Gossypium / Q000033:anatomy & histology / Q000502:physiology*; D006358:Hot Temperature; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology; D012621:Seasons; D013312:Stress, Physiological; D014867:Water / Q000378:metabolism
D045332:Photosystem II Protein Complex; D014867:Water; D002734:Chlorophyll
Drought; Gossypium hirsutum; Heat tolerance; Leaf expansion; Photosynthesis