Deciphering
variability for heat tolerance index in maize hybrids and identification of
stress resilient heterotic combinations
S.
Sandhu*, N. Yousuf, G. Singh and M. Kumar
Department of Plant Breeding and
Genetics, Punjab Agricultural University, Ludhiana-141 004, India
*Corresponding
Author Email :
surindersandhu@pau.edu *ORCiD:
https://orcid.org/0000-0003-0018-3137
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Abstract
Aim:
High temperature at any critical stage for a prolonged duration is documented
to negatively affect the growth and yield related processes in maize.
Therefore, the present study was planned to identify resilience of different
heterotic combinations to heat stress under field conditions.
Methodology: A set of 20 parental lines were used as parents and
21 single cross hybrids raised in kharif 2020 using 16 lines as female parent
and four lines as male parent along with three commercial checks using
randomized block design under two regimes: Normal Sownin mid of February,
i.e., timely sown condition (spring season crop) and late sown in mid of
March (heat stress crop). Data was recorded for yield and its contributing
traits.
Results:
Heat stress led to early onset of flowering, thus resulting in shortening of
vegetative phase. Consequently, days to grain filling period was found to be
reduced (84-106 days) under late sown as compared to 100-123 days under
normal sown condition. Amongst the top performing six hybrids in both normal
sown and late sown conditions, three hybrids were common viz., JH 20003, JH
20015 and JH 20018, though with different ranking, inferring their wider
adaptability and tolerance to heat stress. Under late sown conditions, days
to grain filling (r2=0.55) and thousand seed weight (r2
=0.50) showed significantly positive correlation with grain yield while as
highly significant and negative association was observed between anthesis
silking interval and grain yield (r2 = -0.76). Among the 21
hybrids, three hybrids (JH 20001, JH 20004, and JH 20015) showed greater
potential under heat stress conditions on the basis of yield performance
under stress, percent yield reduction and heat tolerance index.
Interpretation: Based on multiple
selection criteria, three hybrids viz., JH 20001, JH 20004, and JH 20015 were
suggested for commercial utilization after validation. This study also led to
identification of donor inbreds which can contribute to breeding for heat
stress tolerance.
Key words: Grain yield, Heat
tolerance index, Heat stress, Maize, Percent yield reduction
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