Dasberg, S., The Volcani Institute of Agricultural Research, Bet Dagan, Israel
Mendel, K., The Volcani Institute of Agricultural Research, Bet Dagan, Israel

The time rate of germination and the final germination percentage of Oryzopsis holciformis decreased with increasing water stress. The optimum matric potential for germination was-0.005 bar in coarse sand and -0.5 bar in sandy loam soil. This discrepancy was explained by changes in the rate of water-supply to the seed, as determined by the area of contact between seed and germination medium, and by the hydraulic conductivity of the medium.At high soil moisture potentials germination also decreased. Such a decrease was not foundat equivalent osmotic potentials. It seems that this decrease in germination was brought about by the thickening of the water films around the seeds, which interfered with oxygen diffusion. This assumption was supported by determinations with Pt electrodes, and by previous work on germination at lowered oxygen concentrations. © 1971 OXFORD UNIVERSITY PRESS.