Abstract:

For understanding regional desert ecosystem process of drought causing disaster and the influence of drought on growth of Agropyron cristatum and Cornulaca alaschanica, three treatments including continuous drought stress, supplement irrigation and natural growth were designed firstly. Then the changes of two desert herbaceous plants’ morphology and dry matter yield were compared under different soil moisture conditions. The results show that the continuous drought stress made the vegetative growth stage of Cornulaca alaschanica and Agropyron cristatum extend, the reproductive stage and the whole growth period shorten. As affected by drought stress, the growth height, dry matter and cover of Cornulaca alaschanica and Agropyron cristatum decreased, and the effects of drought stress gradually increased. As affected by the continuous drought stress, when volumetric soil water content was only 0.4-0.6 mm, the period of 64 to 73 days after turning green was the inflection point of growth height of Cornulaca alaschanica, and when volumetric soil water content went down to 0.3-0.4 mm, the period of 130 to 135 days after turning green was growth height inflection point of Agropyron cristatum. The period of 106 to 121 days after turning green was the critical stage of drought stress influence on dry matter accumulation of Cornulaca alaschanica when volumetric soil water content decreased to 1.0-1.1 mm. While the period of 181 to 197 days after turning green was key stage of dry matter accumulation of drought stress effect on Agropyron cristatum when volumetric soil water content was about 1.5 mm.

Key words: Cornulaca alaschanica, Agropyron cristatum, drought stress, growth

摘要：

为认识区域荒漠生态系统干旱致灾过程和干旱对冰草、刺蓬生长的影响，设计持续干旱胁迫、补充灌水和自然生长3种处理，比较2种荒漠草本植物在不同土壤水分下外部形态和干物质产量的变化。结果表明： 持续干旱胁迫导致荒漠刺蓬和冰草营养生长期延长，生殖生长期缩短，全生育期缩短。受干旱胁迫影响，荒漠刺蓬和冰草的生长高度、干物质和覆盖度减小，且随生育进程影响逐渐增大。受持续干旱胁迫影响，在土壤体积含水量只有0.4～0.6 mm，返青64～73 d是刺蓬生长高度的拐点；在土壤体积含水量低至0.3～0.4 mm，返青130～135 d是冰草生长高度的拐点。返青106～121 d，土壤体积含水量下降至1.0～1.1 mm，是持续干旱胁迫对刺蓬干物质积累影响关键期；而返青181～197 d，土壤体积含水量低至1.5 mm左右是冰草干物质积累影响关键期。

关键词: 刺蓬（Cornulaca alaschanica), 冰草（Agropyron cristatum）, 干旱胁迫, 生长