The Effect of Petiole Temperature on the Translocation of Carbohydrates From Bean Leaves

Abstract

The present controversial status of the problem of transport rate as related to temperature is briefly summarized in a recent paper by WENT and HULL (8). As pointed out by these authors, the reported Qlo values for translocation range from less than 1 (7,8), to essentially 1 (5), to values greater than 1 (3, 4).The effects of temperature are multiple and greatly complicate an analysis of this problem. It is to be expected, though little data exist for its substantiation, that the effect of temperature on rate of conduction of carbohydrate materials through petioles, will be influenced by temperature effects on numerous other processes occurring in various parts of the plant, such as respiration and assimilation, and the effect these processes have on concentration gradients between regions of export and import. Studies, therefore, in which the entire plant is subjected to different temperatures (4), although contributing much data of value, do not permit a clear analysis of the temperature effect on the process of translocation per se. In the present experiments, therefore, only the petiole temperature was varied, the rest of the plant in all treatments being maintained at a temperature of 20 ± 10 C. Materials and methodsThe report by WEINTRAUB and BROWN (6) that stem elongation of Phaseolus vulgaris var. Black Valentine was directly proportional, within the range of 0 to .75 M, to the concentration of sugar supplied to the leaves suggested that this relationship could be used as a basis of approach for studying the effect of temperature on translocation of carbohydrates. If temperature has an effect on the rate of movement of sugar through the petiole then the amount of sugar reaching the growing tip will vary with temperature and the rate of elongation should vary accordingly. Stem elongation may then be used as an index to the effect of temperature on translocation of sugar. The basic features of the method, therefore, consisted of jacketing the petiole of one primary leaf, immersing the blade in sugar solution and measuring the subsequent elongation of the plant occurring in the dark. Seeds of Phaseolus vulgaris, variety Burpee's Stringless Greenpod (in

The Effect of Hypocotyl Temperature on Translocation of Carbohydrates from Bean Leaves

“…As may be noted from these data, hypocotyl temperature markedly affected the elongation of the stem AB ( fig. 1), the effect being similar to that of petiole temperature observed in earlier studies (2). Maximum transport of both naturally occurring and artificially supplied carbohydrate, as measured by stem elongation, occurred at a temperature of approximately 330 C.…”

“…In a recent paper, SWANSON and BOHNING (2) reported the influence of petiole temperature on the rate of carbohydrate transport from bean leaves, as measured by the rate of stem and leaf elongation in complete darkness. Sugar was supplied to the plants by immersing the blade of the petiolejacketed leaf in 0.75 M sucrose solution.…”

Translocation of Sugars in Cucurbita melopepo IV. Effects of Temperature Change

“…Below 50 translocation is reversibly inhibited and above 450 the process is irreversibly destroyed. The response of sugar movement to temperature change in Cucuirbita resembles that obtained for a number of other higher plant species (2,6,7,12,15,19) …”

“…Below 50 translocation is reversibly inhibited and above 450 the process is irreversibly destroyed. The response of sugar movement to temperature change in Cucuirbita resembles that obtained for a number of other higher plant species (2,6,7,12,15,19) and simulates the response to temperature change of a wide variety of other physiological processes (1,9 (2,7, 12, 15,19). There appears to be no need to asslume the existence of more than 1 mechanism conltrolling movement of the major part of the translocated sugar in any direction in Ciciirbita, as was considered necessary by Htull for the sugar beet (8) and by Hartt for the sugar cane (6).…”

Carbohydrate Partitioning and the Capacity of Apparent Nitrogen Fixation of Soybean Plants Grown Outdoors

“…Vein loading and translocation in the phloem ofwheat plants, however, is largely unaffected by temperatures from 20 to 40C (26). Similar translocationtemperature response curves also have been shown with bean plants (10,24). In the present study, ambient air temperatures were within limits that probably would not decrease the export of carbohydrates out of the leaves or other storage organs of the soybean plant (Figs.…”