The impact of terminal heat stress on yield and heat tolerance of bread wheat

Document Type: Research Paper

Authors

1 Department of Agronomy and Plant Breeding, Ramin Agriculture and Natural Resources University of Khouzestan, Ahwaz, Iran. b

2 Department of Agronomy and Plant Breeding, Ramin Agriculture and Natural Resources University of Khouzestan, Ahwaz, Iran.

3 International Maize and Wheat Improvement Center (CIMMYT), Karaj, Iran

Abstract

In arid and semi-arid regions of the world bread wheat (Triticum aestivum L.) yield is highly
limited due to late season heat stress, mostly occurring during the reproductive phase. Hence the
current study was conducted to evaluate the effect of late season heat stress on grain yield and
yield components of 20 spring bread wheat cultivars. For this purpose, a stripe block experiment
including four sowing dates (6
th of November, 6th of December, 5th of January and 4th of
February) as vertical plots and 20 cultivars in horizontal plots was implemented with three
replicates in North-East of Ahwaz, Khuzestan, Iran during 2007-2008 and 2008-2009 growing
seasons. The results indicated that the main effect of year, sowing date, cultivar and interaction
between sowing date and cultivar were significant for all studied traits. However, no significant
interaction was found between year and other factors. Comparison of means showed that grain
yield in the second year was higher than the first year. The maximum and minimum values
(6.048 ton ha
-1 and 1.754 ton ha-1) were obtained when seed sowing was performed on 6th of
November and 4
th of February, respectively. The maximum grain yield (5.019 ton ha-1) was
related to Atila cultivar whereas the minimum yield (3.662 ton ha
-1) was obtained from Inia 66
cultivar. In general, the maximum and minimum grain yields were produced by Atila cultivar
sown on 6
th of December and Seri82 and Roshan sown on 4th of February, respectively. The
results suggest that Arvand, Vee/Nac, Atila and Baiat cultivars as heat tolerant cultivars and
Roshan, Hamoon, Seri82, Star, Inia66 and Darab2 as susceptible cultivars may be used in heat
tolerance studies.

Keywords