Semipermeable membrane system for subjecting plants to water stress.
A system was evaluated for growing plants at reproducible levels of water stress. Beans (Phaseolus vulgaris L.) were grown in vermiculite, transferred to a semipermeable membrane system that encased the root-vermiculite mass, and then placed into nutrient solutions to which various amounts of polyethylene glycol (PEG) 20M were added to control solution water potential. The membrane (Spectrapor 1) had a minimum molecular weight cutoff that excluded the PEG 20M. The plants equilibrated with the nutrient solution within 1 to 4 days, and exhibited normal diurnal water relations. Use of the semipermeable membrane system to induce water stress reduces many of the problems associated with hydroponic media.
Tingey
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United States Environmental Protection Agency, Corvallis Environmental Research Laboratory, 200 SW 35th Street, Corvallis, Oregon 97330.
Stockwell
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