“…However, a measurable amount of PEG may be absorbed by the plant (1 1,14), and PEG has been reported to reduce phosphorous uptake (7,21,22), translocation (22), and the oxygen content of nutrient solutions (16). These difficulties have been partially overcome by separating the roots from the osmoticum with a semipermeable membrane enclosing a combination of roots and soil (5,8,28,29), or other rooting medium (26). The latter techniques reliably control water stress levels, but significantly restrict the available root volume, thus limiting the size of experimental plant material and the duration ofthe water stress treatment due to microbial degradation of the membranes (26).…”