Abstract
An enhanced level of drought tolerance in wheat (Triticum spp.) may be reached through combining agronomic and physiological traits associated with grain yield under drought conditions. We aimed to explore valuable diversity for the drought tolerance, existed in the core collection of Iranian spring bread wheat landraces. A number of 206 spring bread wheat accessions along with the check cultivar were assessed for grain yield, drought-adaptive traits, and estimated drought tolerance criteria during 2016-17 and 2017-18 growing seasons. Analysis of data using the best linear unbiased predictions (BLUPs) approach revealed that the genotype x environment (GE) interactions accounted for the highest variation in grain yield (36.23%) followed by 1000-kernel weight (35.39%), heading date (21.4%), days to maturity (16.38%), and plant height (5.83%). Using the hierarchical cluster analysis and developed pattern heat map based on the values for the agronomic traits and drought resistance indices, the accessions clustered into nine groups of different sets of agronomic and drought tolerance characteristics. Several accessions with high yield potential, early heading, optimal plant stature and high drought tolerance groups were identified. Three drought selection criteria of stress tolerance index (STI), geometric mean productivity (GMP) and mean productivity (MP) were more effective in identifying accessions producing higher yield under both drought and irrigated conditions. The superior accessions identified in this study may be explored further for breeding new wheat cultivars with enhanced level of drought tolerance.
Highlights
IntroductionWheat is an important crop and one of the most essential commodities in the global market (Curtis & Halford, 2014)
The diversity core collection was developed at CIMMYT by examining 2,403 Iranian bread wheat landraces through field evaluations for heat and drought tolerance and molecular screening based on SNP markers (Crossa et al, 2016)
The annual precipitation during growth seasons exceeded the long-term average (445 mm per year), but crops experienced severe terminal drought due to the lack of rainfall coincided with high temperature during grain filling period
Summary
Wheat is an important crop and one of the most essential commodities in the global market (Curtis & Halford, 2014). Many studies have emphasized increasing wheat production to meet growing global demand (Tilman, Balzer, Hill, & Befort, 2011; Ray, Mueller, West, & Foley, 2013; Mohammadi, 2018). According to Food and Agriculture Organization (FAO, 2018), 746.6 million tons of wheat was produced globally in 2018, to which Iran contributed about 13.5 million tons. In recent decades, predicting severe droughts in the Mediterranean basin and similar regions, has become more complicated due to unfavorable climate changes. Breeding drought tolerant cultivars is considered as the most effective approach towards a sustainable wheat production in the Mediterranean dryland regions. Constructing a core collection, as a subset of entries representing the most of diversities available in the entire collection, facilitates efficient utilization of genetic resources in breeding programs (Upadhyaya et al, 2009; Wang et al, 2013)
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