Development of a dwarf rootstock for Japanese pear.

结果表明，以木瓜（Cydonia oblonga）作砧木，对日本梨'二次成'和'秋梨'的树体生长有明显的抑制作用，可作为一种实用的矮化砧木。结果表明：长叶梨砧木“秋茄”分支汁液中苯甲酸含量约为30 μg/ml，氰化物含量约为2μg/ml，而长叶梨砧木“杜梨”分支汁液中未检出苯甲酸和氰化物。与李属植物相比，秋葵枝条中苯甲酸的含量也达到相同水平。梨叶片切片的呼吸速率分别在含有0至1000 ppm苯甲酸和氰化物的溶液中测定。结果表明，苯甲酸浓度在500 ppm以上时，叶片呼吸强度明显降低，而氰化物浓度在1000 ppm以上时，叶片呼吸强度无明显变化，说明苯甲酸降低了日本梨的呼吸和光合等生理活性，抑制了日本梨的生长。

We found out the tree growth of Japanese pear 'Nijisseiki' and 'Akibae' were redacted remarkably by using Quince EMA (Cydonia oblonga) as a rootstock, and the system seemed to be improved for a practical dwarfing rootstock for pear production. We also investigated the mechanism of the dwarf ness of the pear tree in comparison with vigorating rootstock, P.betulaefolia in this study.The xylem sap from 'Akibae' branch grown on C.oblonga rootstock contained about 3Oμg/ml benzoic acid and a 2μg/ml cyanide, but it did not detected in the sap from the branch on P.betulaefolia rootstock. The shoot of 'Akibae' on C.oblonga also contained benzoic acid as the same level as Prunus species as shown in the previous studies. The respiration rate of a pear leaf sections assayed on a solution containing 0 to 1000 ppm of benzoic acid and cyanide, respectively. The respiration of the leaf sections decreased by a 500ppm or higher benzoic acid solution, while cyanide did not affect to the respiration even in a highest concentration of 1000ppm.These results indicated that benzoic acid generated from Cydonia rootstock reduced the tree growth of Japanese pear with a decrease of physiological activity such as respiration and photosynthesis.