Grassland is one of the main vegetation types in semiarid area． Ｒesearch on the response and mechanism
of forage to soil moisture content is of great significance for the sustainable utilization of water resources and the con-
struction of ecological environment in this area． In this study，four grass species，response of forage morphology，water
physiology，photosynthetic and physiological characteristics to water stress and water recovery process in the Loess
Plateau were analyzed． The results showed that:① Under water stress，the aboveground morphological indexes (i． e． ，
the single leaf area and shoot dry weight) of the grass species were in a decrease trend，but the underground ones (i．
e． ，the root dry weight and root-shoot ratio) were in an increase trend． After re-watering，the forage morphological
characteristics were obviously recovered，and an over compensation of Elymus nutans Griseb． and Lolium multiflorum
Lam． occurred;② Under water stress，the water physiological characteristics of forage were significantly decreased，but
they were gradually recovered after re-watering and resumed to the level of the control group after 2 －3 weeks． These
2 species of leguminous forage could maintain a high water potential and had a strong water conservation capability，
which belonged to a delayed dehydration by increasing water potential，and these 2 species of forages belonged to an
enduring dehydration by developing low water potential under water stress;③ Under water stress，the photosynthetic
physiological characteristics of forage were also in a significant decrease trend，and the short-term water stress could
temporarily improve the photosynthetic capacity of forage;the photosynthetic characteristics of legumes and grasses
were different in sensitivity and adaptation mechanism to drought． Leguminous forage closed the stomata in time to a-
void drought so as to reduce water loss，while grasses sacrificed leaf water to keep stomata open to maintain normal
plant growth．
修改评论