Effects of Ozone on Growth and Photosynthesis of Castanopsis sieboldii Seedlings Grown under Different Nitrogen Loads
Effects of Ozone on Growth and Photosynthesis of Castanopsis sieboldii Seedlings Grown under Different Nitrogen Loads
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DOI：
10.14877/agrmet2.isam08.0.77.0
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发表时间：
2008-09
影响因子：
1.3
通讯作者：
Makoto Watanabe;M. Yamaguchi;H. Matsumura;Y. Kohno;T. Izuta
中科院分区：
文献类型：
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作者：
Makoto Watanabe;M. Yamaguchi;H. Matsumura;Y. Kohno;T. Izuta
为获得日本万年青阔叶树种保护的臭氧临界值，研究了不同氮负荷条件下O3浓度对锥栗幼苗生长和净光合速率的影响。2岁的幼苗生长在12个实验处理，其中包括四个气体处理（木炭过滤的空气和三个水平的O3在1.0，1.5和2.0倍的环境浓度）结合三个N处理（0，20和50公斤公顷-1年-1）在两个生长季节的开顶室。O3处理降低了幼苗的净光合速率和全株干质量，而氮负荷则增加了幼苗的净光合速率和全株干质量。O3和氮负荷之间没有显着的相互作用，全株干质量的幼苗。氮负荷增加了第一、二生长季净光合速率对O3的敏感性。然而，在第二个生长季节的第二次冲洗叶面积的增加补偿O3诱导的净光合速率的下降，在相对较高的氮负荷下生长的幼苗。因此，土壤氮负荷≤50 kg ha-1 year-1时，不影响杉木全株干重的敏感性。草蛉幼苗对O3.根据4 ~ 9月白天O3累积暴露量（AOT 40）与一个生长季的全株干重增长量的关系，提出了一个新的临界O3水平。在一个生长季节中，以AOT 40表示，相当于全株干重增量减少5%，将其评估为22 µmol mol-1 h。
To obtain basic data for evaluating the critical levels of ozone (O3) for protecting Japanese evergreen broad-leaved tree species, we investigated the effects of O3 on the growth and net photosynthesis of Castanopsis sieboldii seedlings grown under different nitrogen (N) loads. Two-year-old seedlings were grown in 12 experimental treatments, which were comprised of four gas treatments (charcoal-filtered air and three levels of O3 at 1.0, 1.5 and 2.0 times the ambient concentration) in combination with three N treatments (0, 20 and 50 kg ha-1 year-1) in open-top chambers during the two growing seasons. The net photosynthetic rate and the whole-plant dry mass of the seedlings were reduced by exposure to O3, while were increased by N load. No significant interaction between O3 and the N load for the whole-plant dry mass of the seedlings was observed. The N load increased the sensitivity of net photosynthetic rate to O3 during the first and second growing seasons. However, the increase in the area of second-flush leaves during the second growing season compensated for the O3-induced reduction in the net photosynthetic rate of the seedlings grown under relatively high N load. We concluded that the N load to the soil at ≤50 kg ha-1 year-1 has no influence on the sensitivity of the whole-plant dry mass of C. sieboldii seedlings to O3. Based on the relationship between AOT40 (accumulated exposure over a threshold of 40 nmol mol-1) of O3 during the daylight hours from April to September and the whole-plant dry mass increment per one growing season, the critical level of O3 for C. sieboldii, which was expressed as AOT40 for one growing season and corresponding to a 5% reduction in the whole-plant dry mass increment, was evaluated as 22 µmol mol-1 h.