In this paper, the response to temperature of three physiological
processes has been examined in detail in seedlings
of sorghum and pearl millet. These have been compared with their field
performance under high temperature
conditions with the aim of developing laboratory-based screening techniques
for seedling thermotolerance.
Membrane thermostability, as assessed by electrolyte leakage, seedling
re-growth and protein synthetic ability
were measured in seedlings exposed to a range of temperatures using a
thermal gradient bar. The effect of
genotype, seedling age and pre-treatment was examined. Differences
between genotypes were only apparent after
seedlings had been given a brief high temperature pre-treatment (2 h at
43°C).
Similar results were found with
all three methods used and their suitability for use in the screening of
large numbers of entries is discussed.
Significant correlation was found between the ability of membrane
thermostability to acclimate and seedling survival in the field.