Burschka Cornelia, Tenhunen J D, Hartung Wolfram
Lehrstuhl Botanik I der Universität Würzburg, Mittlerer Dallenbergweg 64, D-8700, Würzburg, Federal Republic of Germany.
Lehrstuhl Botanik II der Universität Würzburg, Mittlerer Dallenbergweg 64, D-8700, Würzburg, Federal Republic of Germany.
Oecologia. 1983 Apr;58(1):128-131. doi: 10.1007/BF00384552.
Endogenous abscisic acid content (ABA) of Arbutus unedo leaves growing under natural conditions in a macchia near Sobreda, Portugal, was very high (0.25 to 2.3 μg g fresh weight). Highest concentrations were found during the very early morning hours and at midday. During the late morning hours and in the late afternoon ABA concentrations decreased to between one-third and one-fourth of peak values. The samples for ABA content were obtained from both irrigated (Ψ between-10 and-25 bar) and non-irrigated plants experiencing natural water stress during the dry season (Ψ of-50 bar). During the course of the measurement day, stomatal conductance was relatively constant and conductance of watered plants was 50 to 100% greater than that of unwatered plants. No clear correlations between ABA content and stomatal conductance and/or xylem water potential were observed. Despite large differences in water potential and differences in degree of stomatal opening, absolute concentrations of ABA were not found to differ.Small quantities (8-14 pmoles cm leaf area) of ABA were applied to leaves of irrigated and non-irrigated Arbutus unedo plants by injection into the petiole. These extremely small ABA doses resulted in transient reductions in stomatal conductance. The effectiveness with which injected ABA closed stomata was highest during the morning and decreased substantially at midday. Increased sensitivity to injected ABA may again occur in the late afternoon but recent measurements suggest that this may depend on long-term drought experience of the plants. The characteristics of the response to injected ABA were similar in irrigated and non-irrigated plants although irrigated plants responded in general more strongly.
在葡萄牙索布雷达附近一片地中海常绿矮灌木丛中自然条件下生长的草莓树叶片内，内源脱落酸含量（ABA）非常高（0.25至2.3微克/克鲜重）。在凌晨时分和中午时发现其浓度最高。在上午晚些时候和傍晚时分，ABA浓度降至峰值的三分之一至四分之一之间。ABA含量的样本取自灌溉植株（水势在-10至-25巴之间）和旱季经历自然水分胁迫的未灌溉植株（水势为-50巴）。在测量日期间，气孔导度相对恒定，且浇水植株的导度比未浇水植株大50%至100%。未观察到ABA含量与气孔导度和/或木质部水势之间存在明显相关性。尽管水势差异很大且气孔开放程度不同，但未发现ABA的绝对浓度存在差异。通过向叶柄注射，将少量（8 - 14皮摩尔/平方厘米叶面积）ABA施用于灌溉和未灌溉的草莓树植株叶片上。这些极低剂量的ABA导致气孔导度短暂降低。注射ABA关闭气孔的效果在上午最高，中午时大幅下降。在傍晚时分可能会再次出现对注射ABA的敏感性增加，但最近的测量表明这可能取决于植株长期的干旱经历。灌溉和未灌溉植株对注射ABA的反应特征相似，尽管灌溉植株的总体反应更强。
