Root excision and dehydration effects on water uptake in four range species

Abstract

Germinating seeds of crested wheatgrass (Agropyron desertorum), Russian wildrye (Elymus junceus), alfalfa (Medicago sativa), and cicer milkvetch (Astragalus cicer) were dehydrated for 4 days at -22 MPa, and/or their roots were excised, and used as treated materials. In an experiment in root growth boxes, where the seedlings depended for 60 days on the initial soil water supply, seminal primary and seminal lateral roots of grasses penetrated to the same depth. Both types of roots were similarly effective in taking up water, mainly from the upper 50 cm of the soil profile. In a sealed pot experiment under favorable moisture conditions, water uptake increased with seedling age up to 34 and 41 days for crested wheatgrass and Russian wildrye, respectively, and up to the end of the experiment (53 days) for the legume species. Leaf area of grasses was not affected by root excision alone, but it decreased due to the combined effects of root excision and temporary dehydration. Leaf area was generally proportional to water uptake within each species. In all 4 species, root excision and temporary dehydration did not affect transportation rates, while transportation rate decreased as a function of age. Transportation rates were higher in legumes than grasses and were higher in Russian wildrye than crested wheatgrass.