Molyneux D E, Davies W J
Department of Biological Sciences, University of Lancaster, Bailrigg, LA1 4YQ, Lancaster, UK.
Oecologia. 1983 May;58(2):220-224. doi: 10.1007/BF00399220.
Seedlings of perennial ryegrass (Lolium perenne L. S23), cocksfoot (Dactylis glomerata L. S37) and Timothy (Phleum pratense L. S48) were rooted into tubes of soil and plants were either watered well or remained unwatered for a period of seven days. Measurements were made of root water relations and of growth of roots and shoots. Root turgor of Dactylis was larger than that of Lolium and Phleum. As a result of accumulation of solutes, turgor of Dactylis and Lolium was maintained as the soil dried. Phleum roots lost turgor in drying soil and this characteristic correlated well with a water stress-induced reduction in root and shoot growth. Soil drying had marked effects on the rooting patterns of two of the three species. Phleum seedlings which, in wet soil are deep rooting were restricted in their depth of rooting, while roots of water-stressed Dactylis seedlings grew deeper into the profile than did roots of well-watered plants. When water was withheld from plants, deeper rooting apparently resulted in a more favourable shoot water balance which had a beneficial effect on shoot growth.
多年生黑麦草（Lolium perenne L. S23）、鸭茅（Dactylis glomerata L. S37）和梯牧草（Phleum pratense L. S48）的幼苗被种植在装有土壤的试管中，植株要么得到充分浇水，要么连续七天不浇水。对根系水分关系以及根和茎的生长进行了测量。鸭茅的根膨压大于黑麦草和梯牧草。由于溶质积累，随着土壤变干，鸭茅和黑麦草的膨压得以维持。梯牧草的根在干燥土壤中失去膨压，这一特性与水分胁迫导致的根和茎生长减少密切相关。土壤干燥对三种植物中的两种的生根模式有显著影响。在湿润土壤中深扎根的梯牧草幼苗，其扎根深度受到限制，而水分胁迫下的鸭茅幼苗的根比充分浇水的植株的根更深地扎入土壤剖面。当不给植株浇水时，更深的扎根显然导致了更有利的地上部水分平衡，这对地上部生长有有益影响。
