Ultrastructure and biochemical traits of bread and durum wheat grains under heat stress

the yield and grain quality (as well as technological traits) of two heat-stressed genotypes of bread (triticum aestivum l.) and durum wheat (triticum turgidum subsp. durum) having different tolerance to high temperatures after anthesis were investigated. heat stress, during grain filling, triggered grain shrinkage with a reduced weight and ultrastructural changes in the aleurone layer and in the endosperm cells. heat stress also decreased the sedimentation index sds, an effect associated with increased protein content in the grain but with decreased levels of essential amino acids. although the responses to heat stress were similar among the triticum genotypes, it is further suggested that during grain filling, high temperatures might affect gluten strength, diminishing the wheat flour quality.