IMPROVED METHOD FOR MAINTAINING SOIL-MOISTURE LEVELS FOR PLANT SEEDLING RESEARCH

Semipermeable membrane systems are available, yet, plant seedling rese arch requires adaptations that allow for consistent performance by uti lizing materials that encourage adequate growth responses. Soilfilled semipermeable membrane envelopes, enclosed in 1-cm-thick stainless ste el wire frames, equilibrate with polyethylene glycol (PEG) 10000 solut ion with osmotic potential (PSI(pi)) of -0.4 MPa within 36 h and equil ibrate with -0.8 MPa solution within 60 h. Linear relationships existe d between predawn plant water potential (PSI), soil matric potential ( PSIm), and PEG PSI(pi), Improvements compared with previously reported methods included reduced equilibration time and stainless steel frame construction which aided in avoiding Zn toxicity associated with galv anized metal.