Environmentally-Induced Variation in Starch and Non-starch Polysaccharide Content in Wheat

Abstract

Grain samples from cv. Batten wheat were obtained from experiments conducted in a mobile rainshelter in two seasons, and they were analysed for their contents of starch, arabinoxylan and β-glucan. Grain β-glucan content was less than 0·5% in all samples. However, there was a negative relationship between arabinoxylan content and starch content. This was not due simply to starch dilution because the variation in arabinoxylan content was only 15% of that in starch content. There was also a negative relationship between grain weight and drought, and a positive relationship between amount of arabinoxylan accumulated and drought. These results offer a possible explanation for the observed relationship in wheat between high arabinoxylan and low Apparent Metabolisable Energy for poultry, but contrast with the relationship between drought and β-glucan in barley. Varying levels of nitrogen fertiliser did not affect the relationship between the proportions of arabinoxylan and starch, but, by maintaining photosynthesis longer, late-applied nitrogen in combination with plentiful water supply caused an increase in arabinoxylan weight/grain not seen in other drought-free treatments. We conclude that good irrigation management, especially from anthesis, is crucial for good feed wheat quality.