THE EFFECTS OF FEEDING TIME AND NIGHT TEMPERATURE ON THE TRANSLOCATION AND DISTRIBUTION OF ¹⁴C-ASSIMILATES IN TOMATO PLANTS

At day/night temperature of 24°/17°C, ¹⁴C pulse-fed to a single (the largest) leaf was exported rapidly within 2 to 4 hours after feeding regardless of the feeding time, then a slow rate of export continued till the next morning, when the total export amounted to more than 40%. The incipient rapid rate, however, varied somewhat with the feeding time, being comparatively higher in late feeding than in early feeding.

The ratio of the export in the day to that during the following night was calculated to be about 3 : 4, provided that the photosynthetic rate was kept constant during 8 hours of day, which was followed by 16 hours of night.

The distribution pattern, however, was evidently affected by night temperature; the lower the night temperature, the higher the percentage distribution to the lower parts including the roots.

In the experiments described so far, the test plants were, as a whole and including their roots, kept at the definite temperatures.
When air and root temperatures were controlled separately, it was shown that the percentage total export was increased by higher air or root temperature, while the percentage distribution to the lower parts was higher at lower air temperature or at higher root temperature.
Between air and root temperatures, however, the former was not only more quick in its effect but also more effective than the latter and seemed to be a dominant factor determining the distribution pattern.

Symposium on Potential Productivity in Protected Cultivation

Y. Hori, Y. Shishido

https://doi.org/10.17660/ActaHortic.1978.87.23