Responses to drought preconditioning in Eucalyptus globulus Labill. provenances
Responses to drought preconditioning in Eucalyptus globulus Labill. provenances
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DOI：
10.1007/s00468-003-0264-0
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发表时间：
2003-11-01
影响因子：
2.3
通讯作者：
Basci, SO
中科院分区：
文献类型：
--
作者：
Guarnaschelli, AB;Lemcoff, JH;Basci, SO
以蓝桉3个种源5个月生幼苗为试材，在温室盆栽条件下进行36 d的不同水分处理，研究了蓝桉幼苗冠部水分关系及形态对干旱预处理的响应。中度胁迫的植物每6天浇水，严重胁迫的植物每9天浇水。对照植物每天浇水。干旱周期引起的形态和生理特性的显着变化。预处理幼苗的大小，根颈直径，高度和叶面积比对照苗小。冠根比不受干旱的影响。重度胁迫处理下的完全膨压渗透势（psipi（FT））和膨压丧失点渗透势（psipi（TLP））显著低于中度胁迫处理，而渗透调节幅度显著高于中度胁迫处理。在严重胁迫的植物肿胀质量/干质量的减少有助于渗透调节。在随后的驯化试验中，预处理的幼苗表现出较高的气孔导度，黎明前相对含水量和水势值和较低的死亡率比对照植物。这些变量与psipi（FT）显著相关。我们认为，在预处理幼苗中观察到的叶面积减少和渗透调节有助于所选E. globulus种源导致更好的气体交换率和改善的水分状况比非空调植物。种源表现出不同的干旱反应，虽然主要是形态差异。e.球状亚种Tumbarumba的bicostata生长快（直径和高度的相对生长速率较大），说明其对水分胁迫的耐受能力较强。可以预期的是，预处理的幼苗将显示出比未处理的植物更大的水分胁迫耐受性，并且在早期建立期间表现得更好（更高的存活率和早期生长）。
Shoot water relations and morphological responses to drought preconditioning were studied by subjecting 5-month-old seedlings of three provenances of Eucalyptus globulus to different water regimes for 36 days in a greenhouse pot study. Moderately stressed plants were watered every 6 days and severely stressed plants were watered every 9 days. Control plants were watered daily. Drought cycles induced significant changes in morphological and physiological characteristics. Preconditioned seedlings were smaller in size, root collar diameter, height, and leaf area than control seedlings. Shoot/root ratio was not affected by drought. Osmotic potential at full turgor (psipi(FT)) and osmotic potential at turgor loss point (psipi(TLP)) were significantly lower and the magnitude of osmotic adjustment was significantly higher under the severe than under the moderate stress treatment. In severely stressed plants a decrease of turgid mass/dry mass contributed to osmotic adjustment. In a subsequent acclimation test, preconditioned seedlings showed higher values of stomatal conductance, predawn relative water content and water potential and lower mortality than control plants. These variables were significantly related to psipi(FT). We assume that the reduced leaf area and osmotic adjustment observed in preconditioned seedlings contributed to drought acclimation in the selected E. globulus provenances leading to better rates of gas exchange and improved water status than non-conditioned plants. Provenances exhibited differences in their responses to drought, albeit mainly morphological differences. E. globulus subsp. bicostata from Tumbarumba grew more quickly (larger diameter and height relative growth rate) than the other provenances, implying a greater ability to tolerate water stress. It can be expected that preconditioned seedlings will display greater tolerance of water stress than non-conditioned plants and perform better during early establishment (higher survival and early growth).