Grain quality and response of synthetic wheat genotypes to salt stress in an arid region of Iran

Salinity stress is a critical global constraint to wheat production, leading to significant yield reductions and deterioration in grain quality, particularly in arid and semi-arid regions such as Iran. The geographical distribution and salinity levels of soil resources vary across different regions of the country. Out of approximately 6.8 million hectares of salt-affected agricultural land in Iran, around 4.3 million hectares are constrained solely by salinity, posing no other major impediments to sustainable crop production. To address this challenge, advanced synthetic hexaploid wheat lines (SHW), created by combining novel and elite genes from tetraploid wheat (Triticum turgidum L.) and wild ancestors of goat grass (Aegilops tauschii), are proposed as high-potential germplasm for enhancing bread wheat (Triticum aestivum L.). SHW can introduce new genes (such as biotic and abiotic stresses) lost during common wheat evolution. However, concerns remain regarding the quality of synthetic wheat compared to conventional varieties. In the context of global warming and the challenges it presents for plant breeders, particularly in the predominantly arid and dry country like Iran, this study investigates such germplasm for the first time in the region. The aim is to evaluate the performance of a large and selected panel of synthetic hexaploid wheat lines (100 lines) alongside common wheat varieties (nine genotypes) focusing on quality traits, grain-related characteristics, and salt tolerance under various environmental conditions under two consecutive growing seasons. Wide variation and high heritability values were observed for most traits, indicating that the synthetic wheat (SHW) panel possesses valuable diversity for improving salt tolerance in wheat, and the expected gain from selection will be high due to the existing variation. The results showed that grain length (LEN), grain width (WID), grain diameter (DIA), 1000 grain weight (TGW), grain yield (GY), and zeleny sedimentation (ZEL) decreased significantly under salt stress conditions. The value of grain yield, LEN, WID, hardness (HARD), sodium carbonate solvent retention capacity (SCSRC), and sucrose solvent retention capacity (SuSRC) was higher for top 10% of SHW compared to common wheat under stress conditions. The results of correlation analysis indicated that grain yield has a negative correlation with protein content (PRO) and rapid mix test (RMT). Our findings suggest that synthetic wheats present a viable option for bread production compared to conventional wheat, owing to their enhanced resilience and productivity under climate change conditions. The result of this study identified superior genotypes suited for various future studies and the development of new salt-tolerance lines with favorable quality. The Solvent Retention Capacity (SRC) method, developed by Slade and Levine in 1994, is a well-recognized tool for predicting the quality of soft wheat. The AACC 56-11.02 (manual SRC profile) and 56-15.01 (automated SRC profile) are standard methods used for accurately measuring SRC values. The SRC methods had a strong potential to differentiate the quality of wheat genotypes. The superior genotypes identified in this study can be directly utilized or introgressed into wheat breeding programs as donor parents to enhance osmotic tolerance in elite germplasm.