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

Abstract

In a recent paper, SWANSON and BOHNING (2) These studies have now been extended to include the influence of hypocotyl temperature on the rate of carbohydrate transport from bean leaves, using a similar technical approach.Seeds of Phaseolus vulgaris, variety Black Valentine, were planted in sand and allowed to germinate under greenhouse conditions. As soon as the hypocotyls had straightened, selected seedlings were transplanted to .a culture tray containing a complete culture solution. The plants were individually supported by means of split cork stoppers placed around the base of the hypocotyl. The solution was continuously aerated and the plants were allowed to develop under the prevailing greenhouse conditions until used in the experiments.When the primary leaves were nearly expanded and the distance from the base of the hypocotyl to the primary leaf node was approximately five inches, the plants were transferred to specially constructed temperature jackets mounted above asphalt-paraffin-coated metal trays containing complete culture solution and equipped with carbon tube aerators. Each of these units accommodated 10 plants, and four such units were used in each experiment. A modification was made in some of the later experiments in that in place of the metal trays, the roots of each plant were allowed to develop in aerated culture solution in individual glass tubes. The jackets for temperature control were larger (4" x 44" x 41I") than those used in controlling petiole temperature (2), but afforded the same flexibility and accuracy of control. The temperature of the hypocotyl was varied within the range of 7 to 400 C by means of the jackets while the temperature of the rest of the plant was maintained at 25 ± 10 C.

THE EFFECT OF NODE TEMPERATURE ON ASSIMILATION AND TRANSLOCATION OF C14 IN THE SQUASH

“…Varying the temperature of the node has a direct effect on the transport of sugars in the phloem, and the results agree with the view that translocation is decreased by decreasing phloem temperature from about 25 "C (3,4,10,11,12,22,23,26,35). The temperature/translocation response and the derived Qlo values closely resemble those obtained from a wide variety of other physiological processes (2,15) and show no unusual deviations from which a clue concerning the mechanism might have been deduced.…”

“…This mechanism as proposed by Miinch (see ref. These conclusions were disputed on the basis of more direct experimental evidence supplied by Hewitt and Curtis (12) and by Swanson and his collaborators (3,4,22). Went and Hull reasoned that this was so since a lowered phloem temperature must have reduced its metabolic rate.…”

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).…”

A study of several factors affecting the distribution of phosphorus-32 from the leaves ofPisum sativum

“…It is also of interest to note that this inhibition occurred even though the pod was outside of the direct line of transport to other areas of the plant. Böhning et al 7 found a similar "remote control" effect of cooling the hypocotyl of bean plants on movement of carbohydrate to the growing stem tip.…”