Selection methods for malting barley consistently low in protein concentration

The objective of the present study was to identify important environmental factors and establish a multi-environment testing regime that promotes genotype x environment interactions in grain protein concentration (GPC) of malting barley (Hordeum vulgare L.) A reference material was used, consisting of 19 spring barley cultivars with known environmental x genotype variability from numerous yield trials performed in different regions of Europe. The GPC data from these trials were used to calculate a GPC stability index (PSI) based on means of standardized GPC variances. The study was performed over 3 years with outdoor soil-beds in five treatments; three nitrogen regimes and one pre- and one post-anthesis water-stress period. The material was grown in randomized, 22-cm-spaced, hill plots with 12 plants per plot and four to eight replicates. When needed, the plots were drip-irrigated. At sowing, a stationary rain shelter was placed over one bed to establish pre-anthesis drought stress, and moved at anthesis to another bed for post-anthesis stress. At maturity, the plots were harvested, and GPCs and yields were analysed. The variance of GPC over treatments was positively correlated with PSI. The correlation coefficient varied from 0.29 to 0.85, depending on the year, number of treatments and number of replicates. The water-stress treatments, followed by the high-nitrogen-fertilizer treatment, contributed most to the correlations observed, whereas the low-nitrogen treatment had little effect. Studies of seedling root and shoot length from plants grown in hydroponics for 3 weeks revealed that GPC stable cultivars, with a few exceptions, had longer seminal roots and higher root/shoot length ratios. Possibilities of screening for low and stable GPC by using hill plots subjected to different nitrogen- and drought-stress regimes are discussed. (C) 1998 Elsevier Science B.V. All rights reserved.