A Method for Inducing Controlled Moisture Stress on Seedlings
1983
Sikurajapathy, M. | Cappy, J. J. | Gross, H. D.
Selectively permeable sleeves filled with soil were held in tanks containing various polyethylene gylcol (PEG) 10 000 solutions in order to evaluate seedling tolerance to soil moisture stress. The soil columns, made of 7.6 cm diam dialysis tubing (molecular weight (MW) cut off 8000), were fitted to plexiglas bases and placed in tanks containing PEG 10 000 solutions calibrated to provide the desired soil water potentials (−0.01, −0.1, −0.5, and −1.5 MPa). The columns contained 2.5 kg soil. The membrane maintained its integrity over a 30-day period. Soil water moved in response to gradients created by the osmoticum; the small pore size of the permeable sleeves prohibited the PEG from entering the soil. Water loss measured for soil columns immersed in PEG solution maintaining −0.01 MPa potential revealed no movement in either direction. At −0.5 MPa, water moved gradually out of the soil column. At the lower potentials (−0.01 and −0.1 MPa), rapid movement of water out of the soil occurred within 20 h, leading to a loss of 60% of the water in the columns. Water content at various column depths after 12 and 30 days immersion at the different potentials were very uniform. No detectable amounts of PEG were found in roots, shoots, or leaves of mungbean [Vigna radiata (L.) Wilczek] or rice (Oryza sativa L.). The technique makes possible precise control of water-stress intensity (water potential), water-stress duration, and recovery from water stress.
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