Grantz D A, Gunn S, Vu H B
Department of Botany and Plant Sciences and Air Pollution Research Center, University of California at Riverside, Kearney Agricultural Center, Parlier, CA 93648, USA.
Plant Cell Environ. 2006 Jul;29(7):1193-209. doi: 10.1111/j.1365-3040.2006.01521.x.
The mechanism of O3 action on plants remains poorly characterized. Symptoms include visible lesions on the leaf surface, reduced growth and a hypothesized reduction in allocation of carbohydrate to roots. The generality of this latter phenomenon has not been demonstrated. Here, a meta-analysis is performed of all available experimental data, to test the hypotheses that O3 exposure of the shoot inhibits biomass allocation below ground (the root/shoot allometric coefficient, k) and inhibits whole-plant growth rate [relative growth rate (RGR)]. Both k and RGR were significantly reduced by O3 (5.6 and 8.2%, respectively). Variability in k was greater than in RGR, and both exhibited some positive as well as mostly negative responses. The effects on k were distinct from the effects on RGR. In some cases, k was reduced while RGR was unaffected. Slow-growing plants (small RGR) exhibited the largest declines in k. These observations may have mechanistic implications regarding O3 phytotoxicity. There were no effects of type of exposure chamber on sensitivity to O3. The analyses indicate that the O3 inhibition of allocation to roots is real and general, but variable. Further experiments are needed for under-represented plant groups, to characterize exceptions to this generalization and to evaluate O3--environment interactions.
臭氧对植物的作用机制仍未得到充分描述。症状包括叶片表面出现可见损伤、生长减缓以及推测的碳水化合物向根部分配的减少。后一种现象的普遍性尚未得到证实。在此，对所有可用的实验数据进行了荟萃分析，以检验以下假设：地上部分暴露于臭氧会抑制地下生物量分配（根/茎异速生长系数，k）并抑制整株植物的生长速率[相对生长速率（RGR）]。臭氧使k和RGR均显著降低（分别降低了5.6%和8.2%）。k的变异性大于RGR，且二者均表现出一些正向以及大多为负向的响应。对k的影响与对RGR的影响不同。在某些情况下，k降低而RGR未受影响。生长缓慢的植物（RGR小）k的下降幅度最大。这些观察结果可能对臭氧的植物毒性具有机制方面的启示。暴露室类型对臭氧敏感性没有影响。分析表明，臭氧对根部分配的抑制是真实且普遍的，但存在变异性。对于代表性不足的植物群体，需要进一步开展实验，以明确这一普遍现象的例外情况并评估臭氧与环境的相互作用。
