There was a recovery of PSII functionality in all the four cultivars
but the degree of recovery differed depending on the cultivars.
For instance, the sensitive cultivars PWS7 and KKM1353 showed
high rate of recovery but 72 h was not enough for complete recovery
because of the severe inhibition after the third day of heat
stress. This suggests that there was no irreversible damage in the
PSII of these cultivars at the heat stress treatment of 40 ◦C. Mathur
et al. (2011) also reported a slight recovery of the PSII activity in
40 ◦C treated wheat leaves, but no recovery at 45 ◦C. Karim et al.
(1999) found that both Fv/Fm and F
q/F
m remained stable in developing
leaves of maize during heat stress, whereas these parameters
decreased strongly in existing leaves and did not recover after 72 h
of heat exposure