リンゴ幼樹における連続明期処理によるシンク・リミット状態での光合成速度低下の機構(栽培管理・作型)

概要

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The mechanism of photosynthetic inhibition in sink- limited leaves of young apple trees by continuous light (CL) was investigated. By 3 days after CL, the photosynthetic rate (A), stomatal conductance and intercellular CO_2 concentration (Ci) had decreased by 38%, 58% and 9%, respectively, while leaf starch concentration accumulated up to 2.8-fold. Therefore, CL trees were sink-limited. However, A, Ci and stomatal conductance approximately recovered after only 1 day of continuous dark (CD) following 3 days of CL, while leaf starch concentration was markedly reduced to the control level. Therefore, CL trees were rescued from sink- limit. After 3 days of exposure to CL, the initial slope of the A- Ci curve in CL trees was 17% lower than that in the coritrols; that is to say, the c,arboxylation efficiency of CL trees was reduced. However, the initial slope of the A- Ci curve in CL trees was completely recovered after only I day of CD following 3 days of CL. In addition, both the activity and concentration of ribulose-1,5-bisphosphate carboxylase (RuBPcase) were not significantly affected by 3 days of CL. These results suggested that CL-induced photosynthetic inhibition was due to stomatal limitation, rather than decreased activity of RuBPcase.
園芸学会の論文
2004-12-15