Effect of Additional Topdressing with Nitrogen Fertilizer at a Later Growth Stage on β–glucan Content in Grain and Grain Yield of Naked Waxy Barley Cultivar “Kirarimochi”

The β-glucan content in grain is higher in the waxy cultivar of naked barley than in the non-waxy cultivar. Topdressing with nitrogen fertilizer at a later growth stage may increase the β-glucan content in grain. We examined the β-glucan content in the waxy cultivar“Kirarimochi” in comparison with that in the non-waxy cultivar“Toyonokaze” and examined the effect of additional nitrogen fertilization on the β-glucan in the grain throughout the grain filling period. The nitrogen topdressing treatments were : (1) nitrogen fertilizer applied at sowing and tillering stages (control), (2) topdressing at the spike formation stage in addition to the control fertilization, (3) topdressing at the spike formation and anthesis stages in addition to the control fertilization. Waxy cultivar “Kirarimochi” had a higher β-glucan content in grain than the non-waxy cultivar “Toyonokaze”.The additional nitrogen topdressing at later growth stages increased grain yield and spike number compared with the control in both cultivars. When determined at 42 days after anthesis, the β-glucan content was higher in “Kirarimochi” than in“Toyonokaze” and was increased by additional topdressing at later growth stages in “Kirarimochi”. However, at 28 days after anthesis, there was no significant difference in the β-glucan contents between the two cultivars under any of the three treatments. The maturity period was delayed by additional topdressing at later growth stages.