Sionit N, Kramer P J
Department of Botany, Duke University, Durham, North Carolina 27706.
Plant Physiol. 1976 Oct;58(4):537-40. doi: 10.1104/pp.58.4.537.
Plants of two varieties of soybean (Glycine max (L.) Merr.) and two varieties of sunflower (Helianthus annuus L.) were grown in controlled environments and subjected to water stress at various stages of growth. Leaf resistances and leaf water potentials were measured as stress developed. In soybeans the upper leaf surface had a higher resistance than the lower surface at all leaf water potentials and growth stages. Resistance of the upper surface began to increase at a higher water potential and increased more than the resistance of the lower surface. Resistances returned to prestress values 4 days after rewatering. In sunflowers upper and lower leaf surfaces had similar resistances at all water potentials and growth stages. Leaf resistances were higher in sunflower plants stressed before flowering than in those stressed later. Sunflower plants stressed to -16 bars recovered their prestress leaf resistance and water potential a few days after rewatering, but leaves of sunflower plants stressed to -23 bars died. Leaves of soybean and sunflower plants stressed before flowering suffered less injury than those of older plants and sunflowers stressed after flowering suffered more injury than soybeans.
两种大豆品种（大豆（Glycine max (L.) Merr.））和两种向日葵品种（向日葵（Helianthus annuus L.））的植株在可控环境中生长，并在生长的不同阶段遭受水分胁迫。随着胁迫的发展，测定了叶片阻力和叶片水势。在大豆中，在所有叶片水势和生长阶段，叶片上表面的阻力都高于下表面。上表面的阻力在较高的水势下开始增加，且增加幅度大于下表面的阻力。复水4天后，阻力恢复到胁迫前的值。在向日葵中，在所有水势和生长阶段，叶片上表面和下表面的阻力相似。开花前遭受胁迫的向日葵植株的叶片阻力高于开花后遭受胁迫的植株。胁迫至-16巴的向日葵植株在复水几天后恢复了胁迫前的叶片阻力和水势，但胁迫至-23巴的向日葵植株的叶片死亡。开花前遭受胁迫的大豆和向日葵植株的叶片受到的损伤比老植株的叶片小，开花后遭受胁迫的向日葵植株的叶片比大豆植株的叶片受到的损伤更大。
