報告書番号

U99027

タイトル（和文）

ウメ、オオシマザクラ、ソメイヨシノおよびヤマザクラの生育におよぼす人工酸性雨の影響

タイトル（英文）

Effect of Simulated Acid Rain on the Growth of Prunus mume, Prunus lannesiana, Prunus x yedoensis and Prunus jamasakura

概要 （図表や脚注は「報告書全文」に掲載しております）

サクラ属の４樹種（ウメ、オオシマザクラ、ソメイヨシノ、ヤマザクラ）の苗木に、18週間にわたって人工酸性雨（pH3.0, 3.5, 4.0）およびイオン交換水（対照区：pH5.6）を暴露し、可視害発現とともに生育におよぼす影響を調べた。pH3.0では、いずれの樹種にも葉面に壊死班等の可視害が発現した。3種のサクラはウメよりも可視害に対する感受性が高く、pH3.5でも可視害の発現が観察された。一方いずれの樹種でもpH4.0では可視害の発現は認められなかった。乾物生長におよぼす人工酸性雨の影響はいずれの樹種でも小さく、個体乾重量は各pHの処理区間に有意な差が認められなかった。各樹種の植栽土壌pHは人工酸性雨のpH低下にともない低下したが、土壌中の塩基性元素の低下やアルミニウムの増加はみられず、樹木の生育を阻害するほどの土壌性状の変化は認められなかった。

概要 （英文）

Effects of simulated acid rain (SAR) on the visible foliar injury development and the growth of seedlings of Prunus mume, Prunus lannesiana, Prunus x yedoensis and Prunus jamasakura were investigated. The seedlings were exposed to SAR (5:2:3 equivalent mixture of sulfate, nitrate and chloride) of pH 3.0, 3.5, 4.0 and deionized water (control, pH 5.6), at a rate of 20 mm (2.0 mm x 10hr/event), three times per week for 18 weeks (from June 1 to October 6, 1998). The red-brown visible foliar injuries were observed in all species exposed to SAR of pH 3.0. Three cherry species showed visible foliar injuries at pH 3.5 of SAR. However, no species showed visible injury symptoms at pH 4.0. Based on the occurence of visible injury development, sensitivity to SAR was ordered to be P. x yedoensis > P. jamasakura = P. lannesiana > P. mume. In the range of pH 5.6 to 3.0 of SAR, no seedlings showed significant changes in the total dry weight and plant height. Stem diameter of P. lannesiana seedlings increased with lowering rain pH, but those of the other species exposed to SAR did not significantly change compared with those of the control. Cultivated soil pHs exposed to SAR for 18 weeks were slightly reduced with increasing rain acidity applied. However reductions in basic elements and increasing Al concentration in soils were not observed. These results suggested that the threshold pH range to induce visible injury symptoms in Prunus trees was 3.5 - 4.0, while rain pH inducing the growth reduction was below 3.0.

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