Temperature and leaf growth in Lolium perenne. 2. The site of temperature perception.
Leaf extension rates of perennial ryegrass cv. S24 were examined in the field in relation to seasonal changes in soil and air temperature. A technique using heating cables buried in the soil is described and through this the separate effects of soil and air temperature on leaf growth were examined. Results suggested that temperature was effective at the discrete level of the stem apex rather than there being a general effect of soil or air temperature on leaf growth. A technique used in controlled environment to control and vary the temperature in the region of the stem apex independently of soil and air temperatures is described. The results confirmed the sensitivity of the stem apex region to temperature. The importance and possible practical application of these findings is discussed.