Effect of Topdressing Nitrogen Fertilizer at the Spike Formation Stage on Dry-matter Production and Nitrogen Metabolism in Naked Barley Cultivar during the Ripening Period

Abstract

: We investigated the changes in dry weights and nitrogen contents of plant organs during the grain filling period in naked barley cultivar "Toyonokaze." Three treatments with different amounts of nitrogen fertilizer at the spike formation stage (SFS) were given in 2012 / 2013 and 2013 / 2014. Changes in dry weight and nitrogen content of each productive stem were similar in all the treatments in both seasons. Total dry weight increased from full heading time (FHT) to four weeks after FHT in both seasons. Grain weight increased from two weeks after FHT to maturity in 2012 / 2013, and did from two weeks to five weeks after FHT in 2013 / 2014. The amount of nitrogen in the total above-ground part increased from four weeks after FHT to maturity in 2012 / 2013, while it did not increase during the grain filling period in 2013 / 2014. That in the grain increased throughout the grain filling period in 2012 / 2013, but not from five weeks after FHT to maturity. The nitrogen in grain might come not only from vegetative organs by remobilization, but also from absorption from soil during the grain filling period. Thus, how the grain accumulated nitrogen during the later grain filling period varied with the experimental season.