Field experiments were conducted to estimate the combining ability and heterotic effects of maize hybrids under
heat stress condition during summer (mid-March to June). The s2 GCA/ s2 SCA was less than unity for all characters viz.,
days to 50 per cent anthesis, days to 50 per cent silking, anthesis to silking interval, tassel blast, leaf firing, plant height, ear
length, ear girth, shelling %, number of kernels per cob, 100-grain weight and grain yield/plant except ear height indicating
the role of non-additive gene action involved in governing these traits. The parental lines, viz., VL1051 for ASI; VL107578,
VL110232, ZL134937 and VL1018816 for days to anthesis and silking recorded significant gca effects in negative direction.
The parents, ZL126643 and VL1110175 recoded significant gca effects in positive direction for number of kernels per cob
and grain yield. The hybrids, ZL126643 × VL1010877 and VL108868 × VL1110175 recorded significant sca effects for
days to 50% anthesis in negative direction. The hybrid, VL107578 × VL1010877 recorded significant sca effect in positive
direction for plant height and grain yield. The hybrids, VL1011 × VL1110175 (67.13 %), ZL126643 × VL1010877 (40.82
%) and VL126643 × VL0556 (40.21 %) recorded significant standard heterosis for grain yield per plant and VL108868 ×
VL1110175 (30.45%) recorded significant standard heterosis for test weight under heat stress