DIFFERENCES AMONG SEEDLING PEACH CLONES IN STOMATAL RESPONSE UNDER GREENHOUSE CONDITIONS

Twenty three local clones of seedling peach were included to determine the variation among clones in stomatal response to air temperature (T), air vapor pressure deficit (VPD) and soil moisture (PW). Differences in isozyme banding among clones were also studied. Temperature was the variable best related to stomatal conductance in well-watered plants but there were differences in stomatal response. Vapor pressure deficit was significantly related to stomatal conductance in some of the included clones but it was not determinant in others. Under drought cycles, peach stomata did not longer respond to T or VPD but it was related to PW. Stomata of seedling peach clones also responded diversely to drought cycles, varying their rates of stomatal closure. Stomata partially closed at temperatures above 30° C and vapor pressure deficits above 2.84 Kpa. Slight differences among clones in isozyme patterns for malate dehydrogenase (MDH) were recorded.