Effects of Topping on the Growth, the Translocation and Accumulation of Carbohydrates in Corn Plants

[摘要] The present study was carried out to obtain some information about the effects of topping on the growth, the translocation and accumulation of carbohydrates in corn plants, using the variety "Shiratamamochi" as material. The effects of topping treatments by removing six leaves at each of the three stages, silking (T1), early-maturing (T2) and mid-maturing (T3), were investigated by comparing with non-topped controls. The results obtained may be summarized as follows: 1. Toppings at any of the three stages resulted in the reduction of not only the grain yield but also the dry weights of various aphotosynthetic organs, especially of stalks, and the reductions were greater in earlier treatments. 2. In the treated plots, the chlorophyll content in leaf-blades was reduced after the treatment, but the senescence of lower leaves, which received comparatively sufficient light, was slightly delayed. 3. In the control plots, the Brix readings in stalks increased until the mid-maturing stage, while in the treated plots, these decreased immediately after the treatment. 4. As regards the variations of carbohydrate contents in various organs of the treated plots, the contents of reducing, non-reducing sugars and starch proceeded generally lower than those in the control plots, except for the temporary increase of reducing sugar content in the plots treated at silking stage. 5. Judging from the results obtained, it is evident that the reduction of grain yield by topping is due to the reduction of photosynthates which are primarily due to the loss of upper leaves, and that the greatest effect of the treatment takes place during the stages from silking over to early-maturing.

[学科分类] 农业科学（综合）