Interaction of Scion and Stock on Leaf Senescence of Soybean Plants Grafted at Mid-Stem during Ripening

摘要

Leaf senescence is slower in the soybean cultivar Tachinagaha (T) than in the cultivar Enrei (E). Reciprocal grafting of the two cultivars at the basal node showed that this difference was related to roots properties. However, roots had no effect on leaf senescence at a late stage of ripening. To investigate whether the properties of the above-ground parts of plants affect leaf senescence, we grafted the two cultivars at the internode between the 8th and 9th nodes of the stem. Regarding the effect of the scion on the stock, the chlorophyll content of leaves on the E stock was maintained at a higher level when the scion was T than it was E, and the chlorophyll content of leaves on the T stock decreased faster when the scion was E than when it was T. Regarding the effect of the stock on the scion, the chlorophyll content of leaves on the T scion decreased faster when the stock was E than when it was T, although the effect of the stock on leaf senescence of the scion were weaker compared with that of the scion on the stock. Differences in photosynthetic rate were similar to those in chlorophyll content. Thus, it was clear that leaf senescence was affected by the properties of both the higher and lower above-ground parts of plants, in addition to roots.