Dr. Bryla et al., ROOT RESPIRATION IN CITRUS ACCLIMATES TO TEMPERATURE AND SLOWS DURINGDROUGHT, Plant, cell and environment, 20(11), 1997, pp. 1411-1420
Citrus seedlings were grown in soil columns in which the root system w
as hydraulically separated into tyro equal layers; this enabled us to
maintain roots in the upper layer without water for 110 d, The columns
were placed into waterbaths modified so that soil temperatures in the
top layer could be maintained at 25 degrees C or at 35 degrees C, whi
le temperature in the bottom layer was maintained at 25 degrees C, We
hypothesized that, if citrus plants were grown in dry soil for an exte
nded period, root mortality would increase if the cost of maintaining
the roots was increased by elevating the soil temperature. However, du
ring the drought period we did not observe any root mortality, even at
the higher soil temperature, Moreover, we did not find that root resp
iration was increased by prolonged exposure to drought and higher soil
temperature, We did find that root respiration rates slowed in dry so
il, Furthermore, when the soil columns were switched from one temperat
ure treatment to another, root respiration rates in met soil rapidly i
ncreased when moved to a higher temperature or rapidly decreased when
moved to a lower temperature, But after only 4 d, respiration rates re
turned to their original level; root respiration in dry soil was not a
ffected by either short-or long-term shifts in soil temperature, Root
respiration in citrus appears to acclimate rapidly to changes in soil
temperature.