Premium
Longleaf Pine Photosynthetic Response to Soil Resource Availability and Elevated Atmospheric Carbon Dioxide
Author(s) -
Runion G. B.,
Mitchell R. J.,
Green T. H.,
Prior S. A.,
Rogers H. H.,
Gjerstad D. H.
Publication year - 1999
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1999.00472425002800030020x
Subject(s) - photosynthesis , water use efficiency , stomatal conductance , carbon dioxide , soil water , agronomy , xylem , carbon dioxide in earth's atmosphere , chemistry , horticulture , environmental science , botany , biology , soil science , organic chemistry
Abstract Gas exchange responses during a drought cycle were studied in longleaf pine ( Pinus palustris Mill.) seedlings after prolonged exposure to varying levels of atmospheric CO 2 (≈365 or ≈730 µmol CO 2 mol −1 ), soil N (40 or 400 kg N ha −1 yr −1 ), and water (“adequate” and “stressed”). Elevated atmospheric CO 2 concentration increased photosynthesis, tended to decrease stomatal conductance, and increased water‐use efficiency (WUE). Although soil resource availability influenced gas exchange measurements, it generally did not affect the magnitude or direction of the response to CO 2 concentration. However, significant interactions among treatment variables were observed for plant xylem pressure potential. In seedlings grown with high N, a positive growth response to elevated atmospheric CO 2 increased whole‐plant water use resulting in more severe plant water stress, despite increased leaf‐level WUE; however, under low N conditions the lack of a growth response to elevated CO 2 reduced whole‐plant water use, decreased water stress severity, and increased WUE. Photosynthetic response to CO 2 was greatest in the high N treatment at the beginning of the drought cycle, but diminished as water stress increased; however, plants grown with low N showed greater photosynthetic responses to CO 2 later in the drought cycle. Therefore, plant gas exchange rates interact with growth response in determining the severity of water stress under drought and, thus, the ability of elevated atmospheric CO 2 to ameliorate the effects of drought and allow plants to maintain increased rates of photosynthesis may be influenced by the availability of other resources, such as N and water.