Differential Effects of Temperature on Floral Development and Sucrose Content of the Shoot Apex of Wheat

Abstract

The effects of high temperature on the growth and development of the shoot apex of wheat, cv. Warimba, growing in a short photoperiod (8 h) were examined. High temperature (30°C) from germination onwards delayed the initiation of double ridges on the apex in comparison to low temperature (20°C) but did not affect the subsequent rate of spikelet development to stamen initiation. The rate of primordium production on the apex was reduced at the higher temperature and there was a decrease in the final number of spikelets produced. The growth in dry weight of both the shoot and apex was reduced at the higher temperature, but the relative growth rate of the apex was unaffected after double-ridge initiation. The sucrose concentration in the shoot apex tended to be higher at the higher temperature and so it was concluded that the effects of exposure to high temperature on apex growth were not mediated through effects on assimilate supply.