Byres David P, Johnson Jon D, Dean Thomas J
Department of Forestry, University of Florida, 118 Newins-Ziegler Hall, Gainesville, Florida 32611, USA.
School of Forestry, Wildlife and Fisheries, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
New Phytol. 1992 Sep;122(1):91-96. doi: 10.1111/j.1469-8137.1992.tb00056.x.
Four half-sib families of slash pine (Pinus elliottii var. elliottii) were planted in open-top chambers and exposed to ozone and simulated acidic precipitation (3: 7 molar ratio of nitric and sulphuric acids). The 4 ozone treatments were (1) charcoal-filtered air, (2) unfiltered ambient air, (3) twice ambient and (4) three times ambient ozone, with treatments applied 12 h per day, 11 months per year for 28 months. Seedlings were irrigated weekly with one of three rain acidities: pH 33, 4.3 or 5.3 at a total rainfall equivalent of 133 cm per year. Photosynthetic rates were measured approximately every 10 weeks, on the most recently emerged branches each year. In 1988 the 3rd flush was measured, and in 1989 and 1990 the 1st flush of each year was measured. Elevated ozone concentrations generally reduced photosynthetic rates, especially during the summer months, but there was no evidence of either a threshold dose or a simple linear relationship between photosynthesis and ozone exposure. There was a seasonal drop in photosynthetic rates from March to September each year. An ontogenetic decrease in photosynthesis was also evident as trees matured. Stomatal conductance also decreased as the needles aged. Seedlings irrigated with pH 3.3 solution typically exhibited the highest photosynthetic rates, presumably due to a fertilizer effect.
将湿地松（Pinus elliottii var. elliottii）的四个半同胞家系种植在开顶式气室中，并使其暴露于臭氧和模拟酸性降水（硝酸与硫酸的摩尔比为3:7）环境下。4种臭氧处理方式分别为：（1）经活性炭过滤的空气；（2）未过滤的环境空气；（3）两倍环境浓度的臭氧；（4）三倍环境浓度的臭氧，处理方式为每天施用12小时，每年11个月，持续28个月。每周用三种酸度之一的雨水灌溉幼苗：pH值为3.3、4.3或5.3，年总降雨量相当于133厘米。每年大约每10周测量一次光合速率，测量对象为每年最新长出的枝条。1988年测量了第三次新梢，1989年和1990年测量了每年的第一次新梢。臭氧浓度升高通常会降低光合速率，尤其是在夏季，但没有证据表明存在阈值剂量，也没有证据表明光合作用与臭氧暴露之间存在简单的线性关系。每年3月至9月光合速率会出现季节性下降。随着树木成熟，光合作用也出现个体发育性下降。气孔导度也随着针叶老化而降低。用pH值为3.3的溶液灌溉的幼苗通常表现出最高的光合速率，这可能是由于肥料效应。
