晋西常见造林树种叶水势变化研究

Leaf Water Potential Change of Four Common Afforestation Tree Species under Different Soil Water Conditions in the West of Shanxi Province

2005年在山西方山,采用PSYPRO露点水势仪于6月中旬、7月下旬、9月底3个典型晴天测定了3个不同土壤水分条件下紫穗槐、刺槐、仁用杏、臭椿2年生盆栽苗木的叶水势,分析了4种苗木叶水势的日进程及其随季节变化的规律。结果表明,紫穗槐与仁用杏在3个水分处理下随季节变动表现了一致的规律:9月份的叶水势都明显低于6月份与7月份的,且两种苗木在7月份水势变幅都很小,3个处理全天变幅都不过0.5 Mpa;仁用杏在每个月份还表现了各自特定的“水势阈”。刺槐各水分条件下各月水势日进程均呈不对称的单谷曲线,波谷出现在上午10点左右,早晚水势较高,且3个水分处理各月日变化曲线无太大差异;臭椿6月份时各水分条件下都呈不规则“W”形,7月份时水分胁迫者水势严重下降,傍晚也难以恢复。比较各树种严重水分胁迫时叶水势,发现紫穗槐、刺槐与仁用杏有高水势延迟脱水的抗旱机理表现;而臭椿则显示出低水势忍耐脱水的耐旱机理,即其叶组织抗脱水能力较强。

In order to study the diurnal and seasonal change of tree leaf water potential （ψw）,four three-year-old pot-cultured seedlings （Amorpha fruticosa, acacia,kernel apricot, Ailanthus altissima） growing in three situations with different soil water content （SWC）, were measured by using PSYPRO Dew Point Microvolmeter on three sunny days in June, July, and September, 2005, in Fangshan County, Shanxi Province. The results showed that： Amorpha fruticosa and kernel apricot had the lowest water potential in September and had a narrow change range in July, which was below 0. 5Mpa. Moreover, kernel apricot revealed a specific leaf water potential range in every month. Leaf water potential of all acacia samples took a dissymmetrical U shape, with the fall appearing at around 10am. The leaf water potential was higher in the morning and in the evening, not much discrepancy among the three treats. The diurnal change of Ailanthus altissima in different SWC conditions took a crude W shape in June. However, in July, leaf water potential of the treat under severe water stress dropped dramatically, not being able to recover in the evening. Comparing the leaf water potential of each tree species suffered severe water stress, we found Amorpha fruticosa, acacia, kernel apricot, Ailanthus altissima can maintain comparatively high leaf water potential to delay dehydration, while Ailanthus altissima can endure drought in low leaf water potential, that is, Ailanthus altissima leaf tissue has a strong drought-resistance ability.