Influence of decreasing soil moisture on stem water potential, transpiration rate and carbon exchange rate of the lowbush blueberry (Vaccinium angustifolium Ait.) in a controlled environment

Abstract

SummaryA controlled environment study was performed to examine the direct short-term effects of decreasing soil moisture in the lowbush blueberry. Four computer controlled growth chambers were used and stem water potential (SWP), transpiration rate and net carbon exchange rate (NCER) were measured. The experiment was arranged as a randomized complete block design including a control and drought stressed treatment replicated six times using individual growth chambers as the blocking factor. At the conclusion of the experiment, the control treatment displayed a soil moisture value of 75% while the drought treatment had decreased to 50%. After 116 h of nonreplenished moisture loss, the drought stressed plants showed greater variability and a decrease of at least 60% in stem water potential. Decreasing water availability resulted in lowered transpiration and photosynthetic rates (Pn), with a slight decrease in nighttime respiration rates in the drought stressed plants compared with the control plants. Like most drought tolerant plants, the adaptive mechanism of the lowbush blueberry appears to regulate water loss via stomatal and mesophyll conductance.