Genotypic And Environmental Variation Of Hordein Fraction And Malting Quality In Barley

Grain protein content, malt extract, diastatic power, kolbach index and alpha-amino nitrogen content are commonly used as the indicators of malting barley. All these characters are controlled by multi-genes and sensitive to environmental factors. Moreover, they are inter-related and dependent. Beta-amylase and other hydrolytic enzymes are closely associated with these parameters. Hordein, being a main storage protein shows a wide variation in its composition and content over the genotypes and environments, posing the great influence on malting quality.The current research was carried out to determine the genotypic and environmental variation of grain protein content, hordein fraction content, beta-amylase activity and some malting quality parameters, as well as the response of these parameters to nitrogen nutrition and major agronomic practices. The correlation between hordein fraction and malting quality was also analyzed. The main results are as follow:1 Protein and hordein content in barley seeds as affected by nitrogen nutrition and their relations to beta-amylase activityTwo barley cultivars differing in grain size and protein content were used to investigate the effects of 7 nitrogen level in culture solution, cultivar and their interaction on grain protein content, hordein content and beta-amylase activity and the relationship between hordein content and beta-amylase activity in vitro spike culture. The results showed that the contents of protein and hordein fraction, and beta-amylase activity in barley grains increased significantly with the nitrogen level in culture solution. Grain protein content was significantly affected by nitrogen treatment and cultivar, and there was no significant interaction between nitrogen treatment and cultivar. Hordein fraction content and beta-amylase activity were significantly affected by nitrogen treatment and cultivar as well as their interaction. The correlation analysis showed that beta-amylase activity was positively correlated with grain protein and hordein fraction contents, and the ratio of hordein B:C was negatively correlated with total protein content and beta-amylase activity.2 Protein, and hordein content in barley seeds as affected by timing ofnitrogen application and their relations to beta-amylase activityGrain protein content, B and C hordein content were dramatically affected by application rate of nitrogen fertilizer, whereas D hordein content was little affected. Grain protein, B and C hordein contents increased significantly with application rate of nitrogen, whereas D hordein content had less increase. The effect of cultivar on grain protein, C and D hordein contents was larger relative to that of nitrogen treatment. The variation of B hordein content was mainly attributed to nitrogen treatment. Grain weight and beta-amylase activity were significantly affected by nitrogen treatment, but grain yield had little changed over three N levels.Grain protein, B and C hordein contents were dramatically affected by application timing of nitrogen fertilizer, whereas D hordein content was little affected. The treatment with N application at late stage had significantly higher protein and hordein fraction contents than the treatment with N application at early growth stage. The effect of cultivar on B and C hordein contents was larger than that of nitrogen application time, whereas the variations of grain protein and D hordein contents were mainly attributed to the application timing of nitrogen. The treatment with N application at late stage had higher beta-amylase activity in comparison with the treatment with N application at early stage.3 Protein and hordein fraction content in barley seeds as affected by sowing date and their relations to malting qualityThe effect of sowing date on grain protein, hordein fraction contents and some malting quality of two-rowed spring barleys was investigated by using ten commercial cultivars with different grain protein content, and relationships among these traits were examined. The results showed that grain protein and B hordein contents increased with the postponed sowing date, whereas sowing date had no significant influence on C and D hordein contents. There were significant differences in grain protein and hordein fraction contents among cultivars. The coefficient of variation of D hordein content was much larger than that of B and C hordein contents, suggesting that D hordein is much affected by environments than the two other hordein fractions. Beta-amylase activity and diastatic powerincreased significantly with postponed sowing date and malt extract was little affected. Grain protein content was positively and negatively correlated to B hordein content and malt extract, respectively. No significant correlation was found between beta-amylase activity, diastatic power and grain protein content. B hordein was negatively correlated with malt extract, whereas no significant correlation was were detected between C hordein, D hordein and malting quality traits.4 The genotypic and environmental variation of hordein fraction content and some malting qualitiesThe differences among cultivars and environments (locations) ingrain protein content, hordein fraction content, beta-amylase activity and its thermal stability as well as some malting quality were studied by using seven two-rowed spring barley cultivars grown at different ecological regions. The result showed that there was a significant difference in these traits among locations and cultivars. Moreover, the interaction between location and cultivar were also significant. The genotypic effect for B hordein, C hordein, diastatic power and kolbach index and alpha-amino nitrogen was larger than environmental effect. By contrast, the environmental effect for grain protein, D hordein, malt extract, beta-amylase activity and thermal stability was larger than genotypic effect.The correlation analysis showed that beta-amylase activity was positively correlated with diastatic power, kolbach index and alpha-amino nitrogen. Malt extract was negatively correlated with alpha-amino nitrogen. The diastatic power was positively correlated with alpha-amino nitrogen and Z?eta-amylase thermal stability. Kolbach index was positively correlated with alpha-amino nitrogen and Z>eta~amylase thermal stability. Grain protein content was positively correlated with beta-amylase activity, diastatic power, alpha-amino nitrogen, and negatively correlated with malt extract. B hordein content was positively correlated with beta-amylase activity, diastatic power and beta-amylase thermal stability, and negatively correlated with malt extract. C hordein content was positively correlated with beta-amylase activity. D hordein content was negatively correlated with kolbach index.