Stomatal Opening, Transpiration, and Need/e Moisture in Loblolly Pine Seedlings From Two Texas Seed Sources

Relationships among percentage of open stomates, transpiration, and needle moisture content in seedlings of loblolly pine of two Texas provenances were studied under changing soil moisture conditions. Needle moisture content correlated very well with transpiration under favorable moisture conditions, and with percentage of open stomates under soil moisture stress. Transpiration and percentage of open stomates were correlated under a wide range of moisture conditions. Foliage moisture content was still relatively high in both ecotypes when stomates closed and transpiration drastically declined. The Lost Pines seed source appeared to have superior ability to conserve moisture under droughty conditions by closure of stomares and reduction of transpiration. FOREST SCI. 23: 457-462