Physiological traits influencing hardness and vitreosity in wheat grain

ABSTRACT Of the 2 million ha of wheat grown annually in the UK, about 700,000 ha are grown on drought-prone soils. With predicted climate change, the frequency of summer droughts is likely to increase. By mapping genes controlling improved end-use quality under stress, the objective is to provide UK plant breeders with information on genes, and selection methods for traits conferring more stable end-use quality under drought-stress conditions. A mapping population of 48 doubled haploid lines and their parents (Beaver & Soissons), has been investigated over two seasons (2002 and 2003 harvest years), on a drought-prone, loamy sand at ADAS Gleadthorpe. The different lines were grown both with, and without irrigation, in fully replicated field experiments, to examine the differential response of the lines to drought. Physiological assessments were made throughout the season, and yield determined at grain maturity. Hand harvested grain was assessed for mealiness (=100-vitreosity), hardness, grain size, grain weight, grain protein content and measurements made of gel protein quality. The initial observations suggest that the effect of drought was to reduce grain size, increase grain crude protein concentration, and to increase vitreosity of the grain. At the same time, grain protein quality was improved, and grain hardness increased under drought conditions. New QTL have been identified and further work is ongoing to understand the interactions between genotype and environment on grain quality in these lines.