Silviculture and Forest Ecological Studies, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan.
National Council of Research, Via Madonna del Piano 10, Sesto Fiorentino, Florence 50019, Italy.
Sci Total Environ. 2016 Dec 15;573:1053-1062. doi: 10.1016/j.scitotenv.2016.08.183. Epub 2016 Sep 6.
It is widely accepted that elevated levels of surface ozone (O) negatively affect plants. Ethylenediurea (EDU) is a synthetic substance which effectively protects plants against O-caused phytotoxicity. Among other questions, the one still open is: which EDU application method is more appropriate for treating fast-growing tree species. The main aims of this study were: (i) to test if chronic exposure of Salix sachalinensis plants to 200-400mgEDUL, the usually applied range for protection against O phytotoxicity, is beneficial to plants; (ii) to evaluate the effects of chronic exposure to elevated O on S. sachalinensis; (iii) to assess the efficacy of two methods (i.e. soil drench and foliar spray) of EDU application to plants; (iv) to investigate the appropriate concentration of EDU to protect against elevated O-induced damage in S. sachalinensis; and (v) to compare the two methods of EDU application in terms of effectiveness and EDU consumption. Current-year cuttings grown in infertile soil free from organic matter were exposed either to low ambient O (AOZ, 10-h≈28.3nmolmol) or to elevated O (EOZ, 10-h≈65.8nmolmol) levels during daylight hours. Over the growing season, plants were treated every nine days with 200mL soil drench of 0, 200 or 400mgEDUL or with foliar spray of 0, 200 or 400mgEDUL (in two separate experiments). We found that EDU per se had no effects on plants exposed to AOZ. EOZ practically significantly injured S. sachalinensis plants, and the impact was indifferent between the experiments. EDU did not protect plants against EOZ impact when applied as soil drench but it did protect them when applied as 200-400mgL foliar spray. We conclude that EDU may be more effective against O phytotoxicity to fast-growing species when applied as a spray than when applied as a drench. Keymessage: Soil-drenched EDU was ineffective in protecting willow plants against O-induced injury, whereas foliar-sprayed EDU was effective even at the concentration of 200mgL.
人们普遍认为，高水平的地表臭氧（O）会对植物产生负面影响。乙二醛二脲（EDU）是一种合成物质，可有效保护植物免受 O 引起的植物毒性。仍未解决的一个问题是：哪种 EDU 应用方法更适合处理生长迅速的树种。本研究的主要目的是：（i）测试柳树植物慢性暴露于 200-400mgEDUL（通常用于保护免受 O 植物毒性的范围）是否对植物有益；（ii）评估慢性暴露于升高的 O 对 S. sachalinensis 的影响；（iii）评估 EDU 应用于植物的两种方法（土壤淋洗和叶面喷雾）的效果；（iv）确定 EDU 的适当浓度以保护 S. sachalinensis 免受升高的 O 引起的损伤；（v）比较 EDU 两种应用方法的有效性和 EDU 消耗。在无有机物的贫瘠土壤中生长的当年插条，在白天暴露于低环境 O（AOZ，10-h≈28.3nmolmol）或升高的 O（EOZ，10-h≈65.8nmolmol）水平下。在整个生长季节，每隔九天用 200mL 0、200 或 400mgEDUL 的土壤淋洗剂或 0、200 或 400mgEDUL 的叶面喷雾处理植物（在两个单独的实验中）。我们发现 EDU 本身对暴露于 AOZ 的植物没有影响。EOZ 实际上严重损害了 S. sachalinensis 植物，并且这两个实验之间的影响没有区别。当作为土壤淋洗剂施用时，EDU 不能保护植物免受 EOZ 的影响，但当作为 200-400mgL 叶面喷雾施用时，它可以保护植物。我们得出的结论是，当作为喷雾施用时，EDU 可能比作为淋洗剂更有效地防止快速生长的物种对 O 的植物毒性。关键信息：土壤淋洗 EDU 不能有效保护柳树植物免受 O 引起的伤害，而叶面喷施 EDU 即使在 200mgL 的浓度下也是有效的。
