Interrelation of root and shoot temperatures on dry matter accumulation and root growth in tomato seedlings

Abstract

SummaryThree separate experiments were conducted in which tomato seedlings were grown at root zone temperatures of 21°, 26.5° or 32°C. Each experiment differed in the air temperature (11°, 16° or 21°C) of the growth chamber. Total plant dry weight accumulated more slowly at 11° than at 16° or 21°C. Total dry weight and root length were affected by the root temperature treatments at each air temperature. Optimum root temperature, as indicated by dry weight, was 26.5°C except at the lowest air temperature where it was 32°C. Optimum root temperature, as indicated by root length, was 26.5°C at all air temperatures. The rate of increase in root length was reduced at the lowest air temperature or when root temperature was 32°C. Relative growth rate (RGR) was decreased at the lower air temperatures and when root temperature was 32°C. Air temperature had a greater effect than root temperature on RGR except when the root temperature was above 26.5°C. Maintaining higher root temperatures is unlikely to offset the g...