Abstract
Crop yield is reducing due to adverse effects of high temperature. Improvement of physiological status of maize plant against
heat stress is important for a successful hybrid-breeding program. In the present study, six heat tolerant inbred lines, crossed
in diallel mating design to develop F1 progeny. Parental lines including 30F1 crosses were sown in triplicate randomized
complete block design to select better performing inbred lines and F1 crosses for leaf temperature, cell membrane
thermostability, stomatal conductance, transpiration rate and grain yield under normal and heat stress environments. Low
GCA/SCA variance ratio (< 1) showed the predominance of over-dominant gene action for all traits under normal and high
temperature conditions, except osmotic potential (dominant) under high temperature. Three inbred lines, NCIL-20-4, D-135
and NCIL-10-5, showed desirable significant GCA estimates for physiological traits and grain yield under normal and high
temperature. Five F1 crosses, D-103 × NCIL-10-5 (its reciprocal), D-103 × NCIL-30-5, NCIL-20-4 × NCIL-10-5 and NCIL10-5 × NCIL-30-5, proved as the best single crosses for physiological traits and grain yield under heat stress. Selected inbred
lines and F1 crosses will be a good source for development of heat resilient, high yielding maize hybrids in future hybridbreeding programme.
