Beyers Jan L, Riechers George H, Temple Patrick J
Statewide Air Pollution Research Center, University of California, Riverside, CA 92521-0312 USA.
New Phytol. 1992 Sep;122(1):81-90. doi: 10.1111/j.1469-8137.1992.tb00055.x.
Seedlings of ponderosa pine (Pinus ponderosa Laws.) were grown for three years under three atmospheric ozone concentrations - clean air (CF), ambient ozone (NF), and 15 times ambient ozone (NF150)-at a moderately-polluted site in the Sierra Nevada, under either well-watered or drought-stressed conditions. When the trees were 5 years old, photosynthetic capacities of 2-year-old, 1-year-old, and current-year needles were measured during August and September of the 3rd season of exposure. Current-year needles of NF150 trees had higher photosynthetic capacity than NF and CF trees during late summer, an effect due to greatly enhanced photosynthesis in well-watered plants that had lost older needles as a result of ozone damage. This photosynthetic compensation in well-watered NF150 seedlings was related to higher tissue nitrogen concentration in the current-year foliage and possibly to increased inorganic phosphate cycling, both responses to the loss of older needles. Drought-stressed NF150 seedlings were partially protected from ozone damage by decreased stomatal conductance and did not exhibit the same degree of photosynthetic compensation. No differences in photosynthetic rate were found between CF and NF seedlings or between well-watered and drought-stressed seedlings (across ozone treatments) in any needle age class.
在加利福尼亚内华达山脉一个中度污染的地点，将黄松（Pinus ponderosa Laws.）幼苗在三种大气臭氧浓度下培养三年，这三种浓度分别是清洁空气（CF）、环境臭氧浓度（NF）和环境臭氧浓度的15倍（NF150），培养条件为充分浇水或干旱胁迫。当树木长到5岁时，在暴露的第3个季节的8月和9月测量2年生、1年生和当年生针叶的光合能力。在夏末，NF150树木的当年生针叶比NF和CF树木具有更高的光合能力，这是由于在充分浇水的植物中，因臭氧损害而失去老叶后光合作用大大增强。充分浇水的NF150幼苗中的这种光合补偿与当年生叶片中较高的组织氮浓度有关，也可能与无机磷循环增加有关，这两种反应都是对老叶损失的响应。干旱胁迫的NF150幼苗通过降低气孔导度而部分免受臭氧损害，并且没有表现出相同程度的光合补偿。在任何针叶年龄组中，CF和NF幼苗之间或充分浇水和干旱胁迫的幼苗之间（跨臭氧处理）均未发现光合速率存在差异。
