Wheat black point: Role of environment and genotype

Wheat black point is an important quality defect in many areas of the world. The aims of this study were to identify grain tissues involved and to develop a better understanding of the genetic and environmental mechanisms that control black point. Results (of microscopic and genetic investigations) were consistent with control of pigment synthesis being resident in the tissues comprising the grain coat. Analysis of data for a black point susceptible variety revealed a strong correlation between black point and rainfall 20–30 days after anthesis. Application of overhead misting to wheat plots during grain ripening in field experiments appeared to validate this relationship and black point symptoms preceded the appearance of any fungal infestation. A 3-years trials at a high risk field site involving commercial varieties and a doubled haploid population derived from a resistant x susceptible cross indicated significant contributions from genotype, environment and genotype x environment. Germination rate of black pointed developing and ripe grains increased, with no apparent impact on seed viability. The results suggest that black point development can be independent of fungal presence. Furthermore, dark pigment synthesis in susceptible genotypes appears to occur if specific environmental conditions coincide with a sensitive period in grain development.