Visual assessments of infection were made 116 days after sowing (DAS) in 2006 and 113 DAS in 2007, corresponding approximately to early milk

development (GS 75) in each season. For analysis, the scores were converted to percentages using the midpoint of each category on the scale and arcsin x transformed for analysis of variance (ANOVA). In both years, a 1.5 m segment of each row was randomly cut at ground selleck level from each plot just prior to harvest. These samples were used to determine biomass, after drying at 50 °C for 48 h, and grain yield. Final grain yield was also obtained at maturity by harvesting each 10.0 m × 1.8 m plot with a Kew experimental plot header. Grain protein concentration was determined by NIR reflectance. The trial was harvested 145 DAS in 2006 and 154 DAS in 2007.

Data were analysed by ANOVA. The amount of N harvested in the grain protein was calculated from yield and grain learn more protein content, using a conversion factor of protein content of 5.61 times amino acid N content [8]. N in protein was used rather than total grain N (which is about 1.05 times higher) because commercial prices are based on protein content. The Mitscherlich diminishing returns function, Y=α(1–βρN)Y=α1–βρNwhere Y represents grain protein N yield and N represents nitrogen application rate, was fitted to response curves for the susceptible varieties in each year using nonlinear regression in PASW Statistics version 18. This function was shown to give good fits to the response of yield and protein content of wheat in field trials from northern New South Wales [9]. The parameters are interpreted as estimates of maximum yield (α), responsiveness to added N (β) and curvature of the response (ρ) [9]. Stripe rust was the only foliar

disease detected. No rust symptoms developed on the resistant variety Ellison in either year. In 2006 stripe rust severity at GS 75 was high in the susceptible variety HM, and was significantly (P < 0.05) reduced by about half by fungicide treatment ( Fig. 1). Severity was very low in the moderately resistant Org 27569 variety Baxter. Nitrogen had a significant effect on rust severity, with severity increasing in both HM and Baxter as N rate increased ( Fig. 1). Severity of stripe rust was also high in the susceptible variety H45 in 2007 (Fig. 2). The fungicide treatment was more effective (P < 0.0001) in reducing severity than in 2006. Although there was a trend for increased severity with increasing N, this was not significant (P = 0.1). There were no significant effects of fungicide, variety or nitrogen on vegetative biomass in 2006. Mean biomass was 6.22 t ha− 1. The effect on grain yield of the interaction between variety and N application rate was significant (P < 0.05) in 2006. Grain yield was the highest in Ellison, and in HM with fungicide treatment ( Fig. 3). Yield was reduced in HM without fungicide treatment, and was lowest in Baxter.