Potential selection criteria for yield of bread wheat under
early and late heat stresses in a dry irrigated environment
Izzat S.A. Tahir1, 2*, Abdalla B. Elahmadi 2, Osman
S. Abdalla 3, Abu El Hassan S. Ibrahim 4 , Omyma E. Mohammed2
and Noboru Nakata5
1 The United Graduate School of Agricultural Science, Tottori University
680-8553, Tottori, Japan
2 Agricultural Research Corporation, P0 Box 126, Medani, Sudan
3 ICARDA, P0 Box 5466, Aleppo, Syria
4 University of Gezira, P0 Box 26, Medani, Sudan
5 Faculty of Agriculture, Tottori University, 680-8553, Tottori,
Japan
Summary
The predominating high temperatures during early and late stages of wheat in
the tropical and subtropical areas are major limitations for its productivity.
Searching for relevant selection criteria associated with yield under these
areas is of paramount importance. This study was conducted for two seasons at
the Gezira Research Farm, Wad Medani, Sudan, using ten bread wheat genotypes
and three sowing dates (early, optimum and late). In the second season, high
temperatures decreased grain yield by 25% compared with the first season.
The differences between sowing dates were clear in the first season for many
traits including grain yield. Early and late heat stresses caused reductions
of 16 and 32% in grain yield, respectively. Grain yield of the three sowing
dates significantly correlated with biomass, grains/m 2 , spikes/m
2, grain growth rate, biomass growth rate and vegetative growth
rate. In addition, the early sowing grain yield significantly correlated with
grains/spike while that of the late sowi ?ng correlated with harvest index,
thousand kernel weight and grain filling duration. Similar correlations were
also found between the heat stress intensity of yield with most of the counterpart
traits in the early and late sowings. These results suggest biomass, grains/m
2, spikes/m 2 and vegetative growth rate as selection criteria
under early heat stress. Harvest index, thousand kernel weight and grain growth
rate could be used as selection criteria under late heat stress.
Key words: bread wheat, heat stress, selection criteria, heat stress intensity.