Comparison of nitrogen assimilation components among Agrostis species and cultivars

Enhanced nitrogen use efficiency (NUE) in turfgrass systems comprises several factors, including more efficient uptake and assimilation of applied nitrogen (N), as well as reduced N losses to the environment. The objectives of the current research were to evaluate the inter- and intraspecific variation in N use parameters in two Agrostis species, creeping bentgrass (Agrostis stolonifera L.) and velvet bentgrass (Agrostis canina L.), under field and controlled environmental conditions. Measurements included leaf NUE (g dry matter mg^–1 N), leaf N content (mg g^–1 dry matter), leaf and root nitrate reductase activity (NRA)(μmol NO₂^– g^–1 fresh weight h^–1), and root nitrate uptake rate (NUR). Velvet bentgrass cultivars exhibited higher leaf N content and therefore lower leaf NUE than creeping bentgrass cultivars in the field and in a nutrient solution. Differences in leaf NRA were only observed in Agrostis species and cultivars in the field, with higher NRA observed in creeping bentgrass. Velvet bentgrass cultivars grown in a nutrient solution exhibited a 50% higher root NUR than creeping bentgrass, with leaf NRA and N content increasing and leaf NUE decreasing in Agrostis under higher NO₃^– supply.