Understanding wheat growth and the seasonal climatic characteristics of major drought patterns occurring in cold dryland environments from Iran

• Published in: European journal of agronomy 2023-04, Vol.145, p.126772, Article 126772
• Main Authors: Rahimi-Moghaddam, Sajjad, Deihimfard, Reza, Nazari, Mohammad Reza, Mohammadi-Ahmadmahmoudi, Esmaeil, Chenu, Karine
• Format: Article
• Language: English
• Subjects: APSIM model; Breeding; Transpiration; Water supply/demand
• ISSN: 1161-0301; 1873-7331
• DOI: 10.1016/j.eja.2023.126772

Drought is one of the major constraints affecting wheat productivity globally. Understanding of the nature of drought stress (i.e. drought pattern, DP) including its severity, timing and duration is required to deal with the negative impacts of drought on crop production. Drought patterns can be influenced by numerous factors including climatic, soil, and crop growth characteristics. Accordingly, a simulation modelling approach was applied in the current study to capture the characteristics of DPs and their long-term impact on wheat grain yield in dryland cropping systems of north-west Iran. Results showed that light drought patterns (DP1 and 2) were characterized by higher grain yield (3 t ha−1), biomass (10.6 t ha−1), LAI at flowering (2.1), cumulative rainfall from floral initiation to maturity stages (122.6), and cumulative transpiration (158.6 mm), as compared to severe drought patterns (DP3 and DP4). This is mainly because of a lower mean and minimum water supply/demand ratio (sdr) that occurs in severe DPs (0.8 and 0.06, respectively) compared to light DPs (0.92 and 0.22, respectively). Results also indicated that the occurrence of DP4 (53.5%) was dominant across all the dryland study regions while the lowest frequency was simulated for DP3 (3.5%). As drought is frequently happening in the dryland environments through various patterns (i.e. DPs), farmers should understand the patterns of drought that occur in their own regions, and the seasonal climatic characteristics of these drought pattern. Based on the results, it is recommended that (1) farmers sow dryland wheat genotypes that are highly tolerant to drought during their grain filling period for DP4; (2) sow genotypes that have high drought tolerant during vegetative stages for DP3, and (3) use late-maturing genotypes that absorb radiation for a longer period and thus increase photosynthesis and grain yield to take advantage of the optimal environmental conditions under both DP1 and DP2. •Light drought patterns (DP1:2) in wheat agro-ecosystems were characterized by higher grain yield, and LAI at flowering•50% of drought patterns in the studied cold dryland environments belonged to DP4•Genotypes tolerant to terminal drought are recommended for DP4•High drought tolerance during the vegetative stages is recommended for DP3•In DP1:2, late-maturity genotypes perform the best