Repeated mechanical stress from leaf cuvette influences leaf gas exchange.
Marler T. E., Mickelbart M. V.
Author Affiliation: Fairchild Tropical Garden, Miami, FL 33156, USA.
HortScience 27 : 432-434
Abstract : Long-term effects on stomatal conductance of mechanical stress from repeated clamping of a porometer leaf cuvette to laminas of avocado, carambola (Averrhoa carambola), hibiscus (Hibiscus rosa-sinensis), mango and sugar apple (Annona squamosa) plants were determined under greenhouse conditions. Following 10 weeks of applying the mechanical stimulus to mature leaves 7 times during every 4th day, stomatal conductance was lower than for untreated leaves of all species except mango. Similarly, following 10.5 weeks of applying the stimulus once every 4th day to expanding leaves of avocado, carambola, H. rosa-sinensis and sugar apple, stomatal conductance was lower than for untreated leaves of the same age in all species except H. rosa-sinensis. Carambola and sugar apple were more sensitive to the mechanical stress than the other species. Thus, the indirect effect of leaf chamber clamping on gas exchange should be known before any conclusions are formulated regarding environmental, cultural or genetic effects on gas exchange. Random leaf samples from a canopy instead of measurements on a fixed set of leaves may be more appropriate for repeated determinations of leaf gas exchange on a set of plants.