Sobrado M A, Turner Neil C
Department of Environmental Biology, Research School of Biological Sciences, The Australian National University, P.O. Box 475, 2601, Canberra City, A.C.T., Australia.
CSIRO Division of Plant Industry, P.O. Box 1600, 2601, Canberra City, A.C.T., Australia.
Oecologia. 1983 Jun;58(3):309-313. doi: 10.1007/BF00385228.
The effect of water deficits on the water relations and stomatal responses of Helianthus annuus and Helianthus petiolaris were compared in plants growing in the glasshouse under controlled conditions. Unirrigated plants of both genotypes were subjected to two different stress rates in which predawn leaf water potentials declined steadily at either 0.15 MPa day or 0.50 MPa day. In both genotypes water stress induced a gradual and similar decrease in leaf conductance from 1.6 to 0.3 cm s as water potential decreased from-0.5 to-2.0 MPa. The relationship between leaf conductance and leaf water potential was not affected by the rate of stress development.Development of predawn leaf water potentials of-1.3 MPa had no significant effect on the relative water content at zero turgor, the apoplastic water content or the volumetric elastic modulus of whole leaves in either species, but decreased the osmotic potential at full turgor and zero turgor by 0.22 MPa and decreased the turgid weight: dry weight ratio from 10.6 to 8.4 in H. annuus, but not in H. petiolaris. In H. annuus leaves expanded during stress development, changes in the osmotic potential at full turgor induced by water deficits did not disappear on rewatering.
在可控条件下，对温室中生长的向日葵和叶柄向日葵水分亏缺对其水分关系和气孔反应的影响进行了比较。两种基因型的未灌溉植株均经历了两种不同的胁迫速率，黎明前叶片水势分别以每天0.15 MPa或每天0.50 MPa的速率稳步下降。在两种基因型中，随着水势从-0.5 MPa降至-2.0 MPa，水分胁迫均导致叶片导度从1.6降至0.3 cm/s，且下降趋势逐渐且相似。叶片导度与叶片水势之间的关系不受胁迫发展速率的影响。黎明前叶片水势达到-1.3 MPa对两种植物零膨压时的相对含水量、质外体含水量或全叶的体积弹性模量均无显著影响，但使完全膨压和零膨压时的渗透势降低了0.22 MPa，使向日葵的膨压重量：干重比从10.6降至8.4，而叶柄向日葵则未受影响。在向日葵中，胁迫发展过程中叶片会扩展，水分亏缺引起的完全膨压时渗透势的变化在再浇水后并未消失。
