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TEMPERATURE GRADIENTS WITHIN YOUNG MAIZE PLANT STALKS AS INFLUENCED BY AERIAL AND ROOT ZONE TEMPERATURES
ERIC G. BEAUCHAMP and J. K. TORRANCE
Plant and Soil
Vol. 30, No. 2 (April 1969), pp. 241-251
Published by: Springer
Stable URL: http://www.jstor.org/stable/42946743
Page Count: 11
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Root zone temperatures were imposed to study their effect along with those of the air on temperatures of the shoot apices in stalks of maize plants (Zea mays L.). Plants were grown to the 6-to 8-leaf stages in sand culture. Internal stalk temperatures were measured in 21 plants using a Wheatstone bridge with a bead thermistor for two general cases – one with aerial temperatures (Ta) greater than root zone temperatures (Ts) and the other with Ts greater than Ta. Temperature gradients longitudinally within the stalks were found to be primarily a function of the difference between Ta and Ts although the heat of respiration within the stalk apparently had some effect. The effect of both aerial and root zone temperatures in regulating temperatures of the shoot apices of young maize plants was evident from the experimental data. An attempt was made to compare the temperature gradient within a young maize plant stalk to a mathematical model consisting of an isotropie rod with one end immersed in an infinite heat source or sink. The comparison was not good apparently because of the morphology and complex physical nature of the stalk. Linear equations were developed from the experimental data for both cases (Ta < Ts and Ta > Ts) which may be used to estimate the internal stalk temperature at positions in the lower 5 cm portion of the stalk given only the aerial and root zone temperatures.
Plant and Soil © 1969 Springer