8th INTERNATIONAL WHEAT CONFERENCE

filling period. Halna showed very low value of OD although it exhibited heat tolerance on
the basis of MTS, CTD and HSI. The reason would be that Halna got matured very early
and escaped terminal heat stress. It was also observed that there was neither reduction in
grain filling period nor in the yield of Halna due to late sowing. The expression of HSP
90 clearly revealed that the Halna cultivar is true example of heat escaper being a very
short duration genotype.
The present study clearly revealed the importance of heat shock proteins as an important
screening marker over morphological and physiological markers as their expression is
totally dependent on one variable, that is, temperature; however, other markers get influenced
by the environmental variations. On the basis of Heat Susceptibility Index and OD
values observed through ELISA regarding the expression of HSP 90, the four genotypes
namely, HI 385, ACC 8528, PBN 51 and WH 147 were observed as tolerant to terminal
heat stress and Raj 4014 to be the most susceptible. Hence the findings may be helpful in
exploiting these tolerant genotypes in the future breeding programmes for developing the
heat tolerant varieties.
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