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This study evaluated the effects of soil moisture deficit and subsequent watering on the growth of Bromus inermis Leyss., Dactylis glomerata L., Lolium perenne L. and Phleum pratense L. under a non-heat-stressed condition. Plants grown in pots were exposed either to a dry or control soil condition (irrigated 30 and 80 g water /kg soil, respectively) at 10.3 degrees C for 38 days (drought treatment phase), and thereafter to the control soil condition for 27 days (recovery phase). D. glomerata maintained relative water content (RWC) during the drought treatment with the greatest depression in the growth and physiology (photosynthesis and transpiration), suggesting a relatively high ability of dehydration postponement as a drought adaptation mechanism. By contrast, B. inermis showed the smallest growth depression during the drought treatment despite the reduction in RWC, indicating a relatively high ability of dehydration tolerance. During the drought treatment, L. perenne and P. pratense showed similar degrees of growth depression, which was lighter than that in D. glomerata. However, the growth of P. pratense was still strongly depressed as compared with the control during the recovery phase, whereas that of L. perenne received no after-effect of the preceding dry treatment, which demonstrated a relatively low ability of dehydration recovery in P. pretense. The results show that L. perenne has higher overall drought tolerance than P. pratense and D. glomerata.