Open AccessWater Deficits and Environmental Factors Affect Photosynthesis in Leaves of Cucumber (Cucumis sativus)
Author(s) -
Abdul K. Janoudi,
Irvin E. Widders,
J. A. Flore
Publication year - 1993
Publication title -
journal of the american society for horticultural science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.408
H-Index - 80
eISSN - 2327-9788
pISSN - 0003-1062
DOI - 10.21273/jashs.118.3.366
Subject(s) - cucumis , photosynthesis , sucrose , carbon dioxide , raffinose , stachyose , compensation point , chemistry , vapour pressure deficit , horticulture , botany , turgor pressure , assimilation (phonology) , transpiration , biology , biochemistry , linguistics , organic chemistry , philosophy
Cucumber plants were cultured in a greenhouse and subjected to either well-watered or water deficit conditions that reduced leaf water potential to-0.6 MPa. Leaf gas exchange measurements were conducted using an open gas exchange system. Carbon dioxide assimilation (A) attained saturation at a photon flux density (PFD) of 1000 μmol·m -2 ·s -1 (400-700 nm). There were no significant differences in A at ambient temperatures between 16 and 34C. Water use efficiency decreased rapidly with increasing vapor-pressure deficits to 2.5 kPa. Water stressed plants had lower stomata1 conductances and CO 2 assimilation rates. The decrease in A was only partially due to stomata1 closure. The A vs. intercellular CO (C i ) relationship for stressed leaves revealed a change in the CO, compensation point, and that nonstomatal factors were contributing to the decrease in A in stressed plants. Thus, feedback inhibition of A may have occurred through photoassimilate accumulation. The concentrations of sucrose and raffinose were higher, and the concentration of stachyose was lower in leaves of stressed than of well-watered plants.