Growth Responses of Rice Plants to Environmental Conditions : IV. The effect of air- and soil-temperature upon translocation and distribution of <SUP>14</SUP>C.

Abstract

The effects of air- and soil-temperature, regulated separately, upon transIocation and distribution of 14C photosynthate in rice plant were studied. Norin-17 which is a japonica variety adapted to Tohoku district was used at its vegetative growth stage. Higher air-temperature increased the percentage of C assimilates translocated fronl (the fed) leaf-blades, but the effect was not so evident. Relatively more assimilates were translocated and recovered at unexpanded young leaves at higher air-temperatures, but at lower air-temperatures they were distributed more at leaf-sheath, stem and roots, parts of them being stored there as sugars and starch. In general, high soil-temperature showed a tendency to stimulate the distribution of 14C in roots. It was concluded that higher T/R and LB/TOP ratios generally induced under higher air-temperatures were related to faster translocation and greater distribution of assimilates at unexpanded yollng leaves which behaved as a strong sink under these conditions.