Nguyen A, Lamant A
I.N.R.A., Laboratoire d'Amélioration des Arbres Forestiers, Pierroton, 33610 Cestas, France.
Tree Physiol. 1989 Mar;5(1):123-33. doi: 10.1093/treephys/5.1.123.
Hydroponically cultivated Pinus pinaster Ait. seedlings of a drought-sensitive population from France (Landes) and of a more drought-adapted population from Morocco (Tamjoute) were subjected to a progressive increase in water stress by additions of an osmoticum (polyethylene glycol 600) to the nutrient solution. The final osmotic potential (Psi(ms)) of the nutrient solution was achieved over a period of up to 6 days, and ranged from -0.03 (control, no added osmoticum) to -0.8 MPa. In the 6 days during which water stress was imposed, roots elongated faster in the Moroccan provenance than in the French provenance, but the applied water deficits did not inhibit root elongation in either population. Among treatments, root dry weight per unit root length, total root dry weight and root/shoot dry weight ratio increased with decreasing Psi(ms) in both provenances. Both the water potential (Psi(w)) of the roots (apices) and the water potential difference between the roots and the nutrient solution decreased as Psi(ms) decreased. The reduction in Psi(w) was matched by a decrease of comparable magnitude in cell osmotic potential (Psi(pi)) so that root turgor was unaffected by the Psi(ms). Osmotic adjustment was greater, however, in the Moroccan provenance than in the French provenance. Consequently, under the osmotically imposed water stress, the water potential difference between root and nutrient solution was greater in the Moroccan provenance than in the French provenance. Similar changes in plant water relations were observed when seedlings were grown in drying sand.
对水培种植的来自法国（朗德省）干旱敏感种群和来自摩洛哥（塔姆朱特）更适应干旱种群的海岸松幼苗，通过向营养液中添加渗透压物质（聚乙二醇600）使其遭受逐渐增加的水分胁迫。营养液的最终渗透势（Ψ(ms)）在长达6天的时间内达到，范围从-0.03（对照，未添加渗透压物质）至-0.8兆帕。在施加水分胁迫的6天里，摩洛哥种源的根系伸长速度比法国种源快，但施加的水分亏缺并未抑制任何一个种群的根系伸长。在各处理中，两个种源单位根长的根干重、总根干重和根/茎干重比均随Ψ(ms)降低而增加。随着Ψ(ms)降低，根系（根尖）的水势（Ψ(w)）以及根系与营养液之间的水势差均降低。Ψ(w)的降低与细胞渗透势（Ψ(π)）相当程度的降低相匹配，因此根膨压不受Ψ(ms)影响。然而，摩洛哥种源的渗透调节比法国种源更大。因此，在渗透胁迫诱导的水分胁迫下，摩洛哥种源根系与营养液之间的水势差比法国种源更大。当幼苗在干燥的沙子中生长时，观察到植物水分关系有类似变化。
