Abstract
Bread wheat (Triticum aestivum) is a major crop worldwide, and it is highly susceptible to heat. In this work, grain production and composition were evaluated in Portuguese T. aestivum germplasm (landraces and commercial varieties), which was subjected to heat after anthesis (grain filling stage). Heat increased the test weight (TW) in Nabão, Grécia and Restauração, indicating an improved flour-yield potential. Mocho de Espiga Branca (MEB) and Transmontano (T94) showed higher thousand-kernel weight (TKW). Gentil Rosso presented increased soluble sugars, which are yeast substrates in the bread-making process. Ardila stood out for its protein increase under heat. Overall SDS was unaffected by higher temperature, but increased in T94, indicating a better dough elasticity for bread-making purposes. Under heat, lipid content was maintained in most genotypes, being endogenous fatty acids (FAs) key players in fresh bread quality. Lipid unsaturation, evaluated through the double bond index (DBI), also remained unaffected in most genotypes, suggesting a lower flour susceptibility to lipoperoxidation. In Grécia, heat promoted a higher abundance of monounsaturated oleic (C18:1) and polyunsaturated linoleic (C18:2) acids, which are essential fatty acids in the human diet. This work highlighted a great variability in most parameters both under control conditions or in response to heat during grain filling. Cluster analysis of traits revealed a lower susceptibility to heat during grain filling in Ardila, Restauração, and Ruivo, in contrast to MEQ, which seems to be more differentially affected at this stage. Characterization and identification of more favorable features under adverse environments may be relevant for agronomic, industrial, or breeding purposes, in view of a better crop adaptation to changing climate and an improved crop sustainability in agricultural systems more prone to heat stress.
Highlights
Bread is a staple food in many parts of the world
As regards test weight (Table 1), under control conditions Ardila and Grécia presented the highest values (77.8 and 74.1 kg/hL, respectively), while the lowest was observed in Transmontano 94 (T94) (63.2 kg/hL)
Germplasm consisted of seven ancient landraces and traditional varieties from a Portuguese wheat collection [42] preserved in INIAV: Gentil Rosso, Grécia, Mocho de Espiga Branca (MEB), Mocho de Espiga Quadrada (MEQ), Transmontano 94 (T94), Restauração, and Ruivo
Summary
Bread is a staple food in many parts of the world. Eating bread helps consumers to reach their everyday needs of many nutrients. Global warming is an unavoidable ongoing phenomenon [2] and bread wheat (Triticum aestivum L.) production is extremely susceptible to heat stress [3,4]. High temperature can alter biochemical, physiological, and morpho-anatomical behavior in wheat, restraining pollen viability, duration of grain filling, and starch accumulation in the endosperm [4,5]. The most favorable temperature during flowering and grain filling ranges from 12 to 22 ◦C [4]. Temperature above the optimum level results in poor pollen performance and a reduced seed set [5], while postanthesis heat stress decreases starch biosynthesis and induces changes in grain composition and quality [4,6]. Landraces may depict less attractive agronomical traits, but they are a valuable source of genetic variability for breeding as regards adaptation to unfavorable environments, as well as nutritional and quality features
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