Daily variation in transpiring water-consumption rates of three seedling tree species under different drought stresses

صينى. 采用盆栽称重法，研究了不同水分胁迫条件下针叶树种樟子松（Pinus sylvestris var._mongolica）及阔叶树种新疆杨（Populus alba var.pyramidalisa Bunge）和紫穗槐（Amorpha fruticos）的耗水量和耗水速率日变化规律。结果表明，3树种苗木的耗水量和耗水速率在正常水分条件下均呈“单峰型”变化，峰值出现在12:00～14:00；不同树种苗木的最大耗水量和耗水速率差异较大，新疆杨的最大耗水量最高，其次为紫穗槐，樟子松最低，在12:00～14:00时间段，新疆杨、紫穗槐和樟子松平均耗水量分别是59.53，39.25和29.54 g/h，最大耗水速率分别为(247.26±7.18)，(145.92±8.19)，(56.76±9.75) g/(m2•h)；在轻度水分胁迫条件下，3树种耗水量和耗水速率（除新疆杨外）均呈不明显的“单峰型”变化，峰值不在同一时间段出现；在中度和严重水分胁迫条件下，3树种日耗水量和耗水速率相差极小，没有明显的日变化趋势。

إنجليزي. The daily variation of the quantity and rate of transpiring water-consumption of seedlings of three tree species including Pinus sylvestris var. mongolica, Populus alba var. pyramidalisa Bunge and Amorpha fruticos under different drought stresses were studied by using BP3400 precision electronic balance. The result showed that the daily variation of the water-consumption rate of the three tree species presented a convex curve in normal water conditions, in which the maximum value appeared between 12 o’clock to 14 o’clock. The maximum water-consumption quantity and rate varied greatly among different tree species, in which Populus alba consumed the most, sencondly Amorpha fruticos and Pinus sylvestris the least and that the average water consumption rate in the period of 12:00-14:00 and the maximum water consumption rate of Populus alba, Amorpha fruticos and Pinus sylvestris were 59.53, 39.25 and 29.54 g/h and (247.26±7.18), (145.92±8.19), (56.76±9.75) g/(m2•h) respectively. And the daily variation of the water-consumption rate of the three tree species did not present a convex curve under light drought stress conditions and the maximum value appeared at different time. The difference was slightly in medium and serious drought stress conditions and the water-consumption rate had no obvious daily variation.