報告書番号

U98045

タイトル（和文）

ウメ、ヤマザクラ、コナラの土壌水分減少過程における耐旱性の比較

タイトル（英文）

Drought resistance of Prunus mume, Prunus jamasakura and Quercus serrata at decreasing process of soil water content

概要 （図表や脚注は「報告書全文」に掲載しております）

ポット植えのウメ、ヤマザクラ、コナラをガラス室内において無灌水状態で保持し、蒸散反応の変化と障害発現を指標にして、蒸散にともなう土壌乾燥過程における耐旱性を評価した。その結果、ウメは気孔の調節能力が最も低く、葉の萎凋や葉緑素の減少などの土壌乾燥による障害が発現しやすいことが確認された。ただし、落葉により個体当たりの蒸散量を抑制する能力を有することが明らかになった。一方、ヤマザクラは、組織の耐乾燥性が低いとともに、落葉による適応反応も示さなかったことから、最も耐性が低い樹種であると考えられた。これら2種と比較すると、コナラは組織の耐乾燥性が高く、可視障害がほとんど認められなかったうえに、蒸散量調節能力も高く、供試樹種中では最も耐旱性が高いことが明らかになった。

概要 （英文）

Water stress is one of the main factors to induce tree decline, and affects tree growth in combined with other stresses (air pollution etc.). Only processes of forest decline participated with water stress have been investigated, the mechanism of decline have not been clarified. In this study, drought resistance in Prunus mume, Prunus jamasakura and Quercus serrata were estimated under soil water declining process by using the response of transpiration rate, stmatal conductance and visible injury occurrence. Potted trees were irrigated sufficiently until the soil water dripped from under the pots. Two hours later, the soil surfaces and the gapes of pots were closed up with styrene foam board. The pots weight were measured continuously by load-cell in glasshouse. The transpiration rate and the soil water content were calculated by measuring of the pot weights. During this experiment, the gravimetric water contents of soil were reduced from 75 % to 20 %.(1) Variable factors of transpiration The transpiration rates reduced with the regression coefficient (k) decreasing with soil water contents as hereunder. Transpiration rate (E) = regression coefficient (k)×solar radiation (Sn) The relationship between soil water contents and regression coefficients (k) were able to be expressed by sigmoidal function in the all tree species.(2) Visible injury Wilting, reduction of chlorophyll, and defoliation were observed in Prunus mume with decreasing of soil water contents. Prunus jamasakura showed death of whole plant as well as wilting in the process of treatment. On the other hand, visible injury was not observed in Quercus serrata.(3) Regulative capacity of transpiration Quercus serrata had the highest regulative capacity of transpiration by regulation of stomatal aperture, because the rising of stomatal resistance caused at highest soil water content in three species. Regulative capacity of transpiration was lowest in Prunus mume, but the amounts of transpiration in whole trees were decreased by the defoliation. Based on these results, Prunus mume is easy to develop visible drought injury, but could be able to survive under the strong drought condition due to defoliation. On the other hand, Prunus jamasakura is sensitive to drought, since the resistance to tissue drying is low and the effective adaptation for drought does not develop. Quercus serrata is the highest drought resistant species, because of having high regulative capacity of transpiration and strong tolerance to tissue drying.

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