两种药用植物生长和水分利用效率对干旱胁迫的响应

以田间持水量的30%、50%和75%为3个水分处理梯度，研究了决明子和菘蓝2种药用植物在不同水分处理和生长阶段的生长特性，并对稳定碳同位素分辨率(Δ¹³C)和水分利用效率(WUE)特征及二者之间的关系进行了分析．结果表明：与田间持水量的50%和30%相比，决明子和菘蓝在田间持水量75%的条件下具有较高的生长指标，说明这2种植物在充足或适当的水分条件下具有较高的生产力.随干旱胁迫程度的增加，决明子和菘蓝地上生物量和总生物量的Δ¹³C均逐渐减小，而地上生物量和总生物量的WUE均逐渐增加.决明子和菘蓝在不同水分处理之间各指标差异较小，说明这2种药用植物对干旱胁迫反应不敏感．菘蓝WUE与地上生物量和总生物量均呈显著负相关，决明子WUE与根冠比呈显著正相关.

Effects of drought stress on growth and water use efficiency of two medicinal plants.

Growth characteristics, stable carbon isotope discrimination (Δ¹³C), water use efficiency (WUE), and their correlation of Cassia obtusifolia and Isatis indigotica were measured at three soil water levels, i.e., 30%, 50% and 75% of field water holding capacity (FWHC), and at three growth stages. The growth indices of the two medicinal plants at 75% of FWHC were higher than those at 30% and 50% of FWHC, suggesting that the two medicinal plants could obtain high production under sufficient moisture condition. The Δ¹³CA (aboveground biomass based Δ¹³C) and Δ¹³CT(total biomass based Δ¹³C) decreased, and the WUE-A(aboveground biomass based WUE) and WUE-T(total biomass based WUE) of C. obtusifolia and I. indigotica increased with the increasing degree of drought stress. The growth indices of the two medicinal plants had little difference in the different water treatments, which indicated that the two medicinal plants were insensitive to drought stress. Water use efficiency of I. indigotica had significant negative relationships with aboveground biomass and total biomass, while that of C. obtusifolia had a significant positive correlation with the root/shoot ratio.