Jiang Y, MacDonald S E, Zwiazek J J
School of Forest Resources, University of Georgia, Athens, GA 30602, USA.
Tree Physiol. 1995 Apr;15(4):267-73. doi: 10.1093/treephys/15.4.267.
To determine the effects of lifting time and storage on water-stress resistance of nursery-grown white spruce (Picea glauca (Moench) Voss) seedlings, we compared gas exchange, water relations and mortality of 3-year-old seedlings lifted in October 1991 and stored at -2 degrees C for 3 months with seedlings lifted in January 1992. The seedlings were placed in nutrient solution and subjected to -1.1 or -2.7 MPa water stress induced by polyethylene glycol 3350 for 9 days. Water stress, but not lifting time, had a significant effect on seedling net assimilation, symplastic volume and turgor loss point. In a second experiment, seedlings lifted in October 1991 were stored at -2 degrees C for 7 months and compared with seedlings lifted in May 1992. The seedlings were planted in pots, and their gas exchange and water relation parameters measured in response to gradual water stress. The results suggest that prolonged cold storage retards photosynthetic recovery of seedlings after planting. Higher rates of net assimilation in seedlings lifted in May were not directly related to their water status. Nonstomatal limitations were the primary factor influencing photosynthetic rate. We conclude that the inferior ability of cold-stored seedlings to tolerate water stress was due to poor osmotic adjustment and a lag in recovery of photosynthesis.
为了确定起苗时间和贮藏对苗圃培育的白云杉（Picea glauca (Moench) Voss）幼苗抗水分胁迫能力的影响，我们比较了1991年10月起苗并在-2℃贮藏3个月的3年生幼苗与1992年1月起苗的幼苗的气体交换、水分关系和死亡率。将幼苗置于营养液中，用聚乙二醇3350诱导产生-1.1或-2.7 MPa的水分胁迫，持续9天。水分胁迫而非起苗时间对幼苗净同化率、共质体体积和膨压丧失点有显著影响。在第二个实验中，将1991年10月起苗的幼苗在-2℃贮藏7个月，并与1992年5月起苗的幼苗进行比较。将幼苗种植在花盆中，测定其气体交换和水分关系参数以响应逐渐增加的水分胁迫。结果表明，长时间冷藏会延缓幼苗种植后光合恢复。5月起苗的幼苗较高的净同化率与它们的水分状况没有直接关系。非气孔限制是影响光合速率的主要因素。我们得出结论，冷藏幼苗耐受水分胁迫能力较差是由于渗透调节不良和光合恢复滞后。
