Relation between nitrogen nutrition index and production of spring malting barley

Although the nitrogen nutrition index (NNI) is a widely used indicator of plant nitrogenstatus, no model of NNI calculation for spring barley (Hordeum vulgare) reflecting also specificmalting requirements on grain has been published. The aim of this study was to determinean optimal range of the nitrogen nutrition index (ratio of nitrogen concentration in shootbiomass to critical nitrogen concentration) with respect to optimal grain protein content(N × 6.25 = 9.0 – 11.5 %), plump grain (grain > 2.5 mm) yield and lodging of spring maltingbarley during 7-year (2007 – 2013) strict field experiments realized under the conditions of threeexperimental sites in the Czech Republic. A dose of 80 kg N/ha and 130 kg N/ha, respectively,was applied in mineral fertilizers. The nitrogen nutrition index was determined at the BBCH 30(beginning of stem elongation) and BBCH 45 (late boot stage) growth stages. The most suitableindicators for evaluation of the nitrogen concentration in shoot biomass of the spring maltingbarley in our experiments proved to be Justes et al.´s model Nc = 5.35 DM(-0.442) designated forwinter wheat and Zhao´s model Nc = 4.76 DM(-0.39) designated for winter barley, where DM isshoot dry matter in t/ha. The nitrogen nutrition index for spring malting barley should notexceed a value of NNI = 0.80 and NNI = 0.90 using the Justes et al.´s model and the Zhao´s oneduring the BBCH 30 – 45 growth stages.