半干旱黄土丘陵区五种植物的生理生态特征比较

通过测定陕北黄土丘陵区5种植物在旱季的光合速率、蒸腾速率和叶水势日变化,将植物划分为不同的水分生态适应类型.结果表明:柳枝稷的光合生理特征属于高光合、低蒸腾和高水分利用效率类型,其抗旱适应性特征属于高水势延迟脱水类型；苜蓿属于高光合高蒸腾低水分利用效率类型,耐旱性为高水势延迟脱水型；达乌里胡枝子属于低光合、低蒸腾、低水分利用效率类型,耐旱性为高水势延迟脱水型；白羊草属于高光合、蒸腾较高的水分利用效率中等型,耐旱性属于能忍耐脱水造成的低水势的一类.沙打旺属于高光合中等蒸腾速率中等水分利用效率类型，耐旱性为低水势延迟脱水型.

Comparison of ecophysiological characteristics of seven plant species in semiarid loess hilly-gully region

The diurnal course of photosynthetic rate, transpiration rate, and leaf water potential (psi L) of five plant species in North Shaanxi loess hilly-gully region were measured in dry seasons. Based on the daily maximum photosynthetic and transpiration rates, daily total assimilation and transpiration, and diurnal change characteristics of psi L, the test plants were classified into different eco-adaptation types. Panicum virgatum L. had high photosynthetic rate, low transpiration rate and high water use efficiency (WUE), and its drought adaptation strategy was to delay dehydration by developing high psi L. Medicago sativa had high photosynthetic and transpiration rates but low WUE, while Lespedeza dahurica had low photosynthetic and transpiration rates and low WUE. Their drought adaptation strategies were the same, namely, by increasing psi L delay dehydration. Bothriochloa ischaemum had high photosynthetic rate, relative high transpiration rate and medium WUE, and its drought-resistant strategy was to decrease psi L to endure dehydration. Astragalus adsurgens had similar characteristics in diurnal courses of photosynthesis with B. ischaemum, and its drought adaption strategy was to delay dehydration by developing low psi psi L.