湛水処理をした栄養成長期と果実肥大期のトマトにおける^<13>C光合成産物の分配および出液速度の変化(土壌管理・施肥・灌水)  [in Japanese] Distribution of ^<13>C-photosynthates and Changes in Bleeding Rate under Waterlogged Conditions at Two Developmental Stages in Tomato Plants(Soli Management, Fertilization & Irrigation)  [in Japanese]

トマトの果実肥大期が栄養成長期と比較して濃密を受けやすい原因を明らかにするため,乾物重,新規固定炭素の分配と出液速度について調査した.栄養成長期と果実肥大期のトマト地上部全体に5時間^<13>CO_2を同化させ,同化終了直後から43時間湛水処理を行った.湛水区の新規同化産物の根への分配は,両時期とも対照区と同程度であったが,栄養成長期の9%と比べて果実肥大期では2%と非常に少なかった.出液速度は両時期とも湛水処理により低下した.根重当たりの出液速度は栄養成長期よりも果実肥大期で低い値となった.果実肥大期で栄養成長期と比較して湿害の程度が大きいのは,根への同化産物の転流割合が相対的に低いステージであることと,根の生理活性の低下程度が大きいことに起因すると考えられた.

This study investigated causes of increased susceptibility to excess moisture injury during the fruit developmental stage compared with vegetative stage in tomato plants. Dry matter, distribution patterns of photosynthates and bleeding rate in tomato plants under transient waterlogged condition were investigated. After whole shoots of tomato were exposed to ^<13>CO_2 for 5 hours, the tomato plants were waterlogged for 43 hours. The waterlogged treatment did not affect the distribution of newly fixed carbon to the roots during either stage of the tomato plant. Only 2% of assimilates translocated to the roots during the fruit developmental stage under waterlogged condition. The bleeding rate was lower in both stages following waterlogged treatment. The bleeding rate per unit root dry mass was lower during the fruit developmental stage compared with that at the vegetative stage. Therefore, it is suggested that relatively low distribution rate of photosynthate to the root, which is natural during the fruit developmental stage, and the greater decline in root activity would be factors promoting increased susceptibility of tomato to excess moisture injury.