Effects of developmental stages and topping on photosynthesis, translocation and distribution of 14C-assimilates in tomato [Lycopersicon esculentum] plant
1990
Shishido, Y. (National Research Inst. of Vegetables, Ornamental Plants and Tea, Morioka (Japan). Morioka Branch) | Arai, K. | Kumakura, H. | Yun, C.J. | Seyama, N.
Studies were carried out to elucidate the changes of photosynthetic ability at different leaf ages and developmental stages of the whole plant. Furthermore we attempted to clarify the effects of topping on photosynthesis, translocation and distribution of photosynthetic assimilates in tomato plants. The maximum photosynthetic rate was obtained from young leaves, about 100 square-cm in size. The photosynthetic rate of individual leaf gradually decreased with time and with the leaf development. This tendency coincided with a decrease in nitrogen content and chlorophyll content with time and with the leaf development. However, the amount of photosynthesis per leaf increased in spite of a decrease in the photosynthetic rate because the leaf area also increased. Therefore the decrease in the degree of increment of leaf area results in a decrease of the amount of photosynthesis per leaf. It can be shown, however, that the time of maximum amount of photosynthesis in the respective leaf is the same as the maximum development of the sinks near each leaf. The photosynthetic rate of each leaf and the degree of decrease in the photosynthetic rate did not change considerably by topping, since the degree of increment of leaf area increased by topping, the amount of photosynthesis per leaf was greater than the control leaf. The effects of topping seem to be the removal of the sinks. Therefore, the rate and amount of development of the fruits near the place of topping was enhanced by the loss of the competitor. The translocation and distribution of 14C-assimilates were affected by topping. The degree of those changes, however, is influenced by the position and distance from the place of topping or by the new balances of the source-sink relation of each leaf
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