Studies on the Assimilation and Translocation of ¹⁴CO₂ in Ladino Clover : VII. Effect of temperature, especially low temperature on the translocation of ¹⁴C-assimilates

Abstract

The effect of temperature, especially low temperature on the translocation of ¹⁴C-assimilates was examined. 1) At the favorable temperature for growth (15°-25°C), the ¹⁴C-assimilates of ladino clover moved at the speed of about 30 cm/hr. At 10°C, speed was reduced and the speed of ¹⁴C-assimilates was about 20 cm/hr. 2) The basipetal translocation of the ¹⁴C-assimilates was faster and more dominent than the acropetal when ¹⁴C was fed leaf No. 4 from growing points. The gradient of ¹⁴C-assimilates to the basal part of plant (i.e. basipetal) was more clear and sharp than those of acropetal. 3) Total amount of translocated ¹⁴C-assimilates was greater in the high temperature than the low temperature in the range of 10°-25°C. 4) When plants grown at 20°C were transfered to low temperature, speed of translocation was reduced, particularly below 10°C. At 0°-2°C, and 5°C translocation was almost completely ceased. But plants grown at low temperature, 5°C, showed the adaptation to the condition of low temperature, and the inhibition of the low temperature on the translocation was reduced. At any rate, the low temperature reduced the speed of translocation of ¹⁴C-assimilates. It seemed that this will be one of the reason for delayed growth at low temperature, especially in the case when the plants were exposed to the low temperature suddenly.