A Comparison of the Ecology of Deschampsia Cespitosa and Dactylis Glomerata in Relation to the Water Factor: II. Controlled Experiments in Glasshouse Conditions

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Abstract
The effects of waterlogging and varying degrees of soil water deficit on germination and growth of Deschampsia caespitosa (L.) Beauv. and Dactylis glomerata L. were investigated in controlled experiments. Germination and early seedling growth of both species were reduced if the soil water deficit exceeded 10 mm between waterings. In plants which were first grown for 8 wk from germination with free watering, and were then subjected to water deficit, the increase in dry weight was not reduced by the most extreme treatment, in which a soil water deficit of .apprx. 200 mm developed during the ensuing 7 wk. There was little consistent evidence of any difference in response of the 2 species to soil water deficit. A high water-table reduced both germination and growth much more in Dactylis glomerata than in Deschampsia caespitosa. Dry matter production of Dactylis glomerata was about twice that of Deschampsia caespitosa in all treatments except high water-table, when production of the 2 species was approximately equal. The range of soil water conditions in the experiments was similar to that observed in a field study, and the experiments supported conclusions from the field study that Deschampsia caespitosa is characteristic of wet soils because it is tolerant of poor aeration, and is excluded from drier soils by competition.