Nitrogen Management for Enhanced Value of Irrigated Barley.

Waxy barley (Hordeum vulgare L.) with high amylopectin has enhanced value as a food crop, a source of fractionated protein, starch, or soluble fiber, but information on nitrogen (N) fertilization effects on enhanced traits in irrigated waxy barley is limited.   Furrow-irrigated field studies were conducted at Parma, ID with 'Merlin' and 'Salute' spring genotypes fall or spring planted for the 2006, 2007, and 2008 seasons.  Varieties were the main plots and N treatments were subplots in a randomized complete block - split plot design with three or four replications. “Early” N as dry urea was applied preplant or late winter (0, 67, 134 and 202 kg ha^-1) and “late” N was applied at heading (0 or 40 kg ha^-1) to 67 and 134 kg ha^-1 early N treatments. Late N was applied as top-dressed dry urea (DU), foliar fluid urea (FU), or foliar urea- ammonium nitrate (FUAN).  Enhanced quality traits measured included total protein, Beta-glucans, and starch as well as the starch viscosity profile.  Increasing early season N, as well as late N, increased protein, B-glucan concentrations in two of three years, and starch final viscosity, but reduced starch concentration.  Foliar late N tended to be more effective for increasing protein in two years, but less effective in the third year.  Late foliar N sources did not differ in their effects on other barley traits.  Protein was positively correlated with B-Glucan but inversely related to starch concentrations.  Within varieties, B-glucan and starch concentrations were negatively correlated.  Hulless Merlin was higher in starch and protein concentrations, and lower in B-glucan concentrations.  With added N the yields of protein, B-glucan, and starch were as high or higher for Merlin than for Salute.  Both fertilizer N management and waxy variety selection can be critical depending on the barley food quality parameter of interest.