Heat stress significantly decreased the maximum photochemical
efficiency (5–36%) and quantum yield of PSII (14–63%) in four
wheat cultivars grown in two temperature conditions and different
growth stages. The results confirm the reproducibility of the
performance of these four cultivars namely, C518 and KK3 (heat
tolerant) and PWS7 and KKM1353 (heat susceptible) according
to their performance during selection based on Fv/Fm under heat
stress in climate chambers (Sharma et al., 2012). The cultivars also
varied for their rapid recovery capability after heat stress. Furthermore,
the four cultivars showed significant differences with
respect to morphological traits such as flowering time, plant height,
number of tillers and spikes and grain weights under two different
growth temperatures, indicating that the pre-acclimation of
plants to slightly higher growth temperatures impart less heat
induced effects/damages during a subsequent heat stress treatment.
The study suggests that the growth temperatures not only
influenced the developmental rate and yield of the cultivars, but
also reduced damages caused by heat stress. Thus, understanding
the mechanisms behind temperature adaptation and acclimation
of the diversified wheat cultivars has novel perspectives to understand
how crop performance can be improved under changing
climate conditions.