The Effect of Temperature upon Translocation of Carbohydrates in the Tomato Plant.

One of the most controversial problems in plant physiology is that of translocation of organic materials inside the plant. This is mainly due to a lack of information. In spite of the investigations of Crafts, Curtis, Mason, Munch, Phyllis, Schumacher and many others, we need much more basic information before we will have a proper insight in this problem and before we can accept a satisfactory theory of translocation. The recent work of WENT (17) had stressed the importance of the process of sugar translocation at higher temperatures, since this seemed to be the limiting process in the growth and development of tomato plants. Furthermore, it had been concluded on the basis of three different lines of experimental approach, that the Q10 of sugar transport was less than 1 in the tomato plant. In subsequent work more evidence was collected for the low Q1o of sugar translocation, not only in the tomato plant (WENT 18, WENT and ENGELSBERG 21, WENT and CARTER 20), but also in the chili pepper (DORLAND and WENT 7). A Q1o smaller than 1 was contrary to the accepted view, that at low temperatures sugar translocation decreases. This view was based on the work of several investigators. CHILD and BELLAMY (2) had observed a greatly increased outgrowth of adventitious buds on the leaves of Bryophyllum when their petioles were chilled to 2.5 4 C for a few days. This seemed to indicate a greater concentration of carbohydrate in the leaves with chilled petioles, but no direct sugar determinations were carried out to support this interpretation. Therefore the results might as well be interpreted as an increased rate of movement of other bud growth factors towards the leaves. CURTIS (4) and CURTIS and HERTY (5) studied the effect of temperature of the petiole on the loss in darkness of dry material from the primary leaves of the red kidney bean (Phaseolus vulgaris L.) It was found that cooling the petioles to 0.5-4.5' C greatly retarded translocation of carbohydrates from the leaf blades. However, if the treatment was continued for 17-20 hours, a significant amount of transport took place. Sugar transport was also retarded when the entire plant was kept at temperatures of 0-2° C. At intermediate temperatures of 7-11° C sugar translocation appeared to be intermediate between the values found for low temperature and values for higher temperatures of 17-24° C. Chilling of the main stem just below the first pair of leaves for two days to a temperature of 2-5° C clearly showed that the upward movement of