GRAIN PROTEIN CONCENTRATION AND ITS STABILITY IN A SET OF WINTER WHEAT CULTIVARS, GROWN IN DIVERSE ENVIRONMENTS AND MANAGEMENT PRACTICES

Bread making industry and wheat markets have strict requirements for grain protein concentration (GPC), as there is a strong positive relationship between grain protein concentration and bread volume and texture. The objective of this paper was to identify genotypic differences between 23 Romanian and foreign winter wheat cultivars in GPC, as related with grain yield, and in GPC stability across environments. Samples from yield trials performed during 30 environments (4 locations, 3 years and different management systems), widely different in nitrogen availability and yield potential, were analyzed for grain protein content. Grain protein concentration was mainly determined by the environment, but average differences between cultivars were significant when tested against the genotype*environment interaction. More than 40% of the GPC variation between cultivars could be explained by the negative correlation with grain yield, but several cultivars had a higher GPC than expected based on their average yield. This suggests some possibilities in breeding for both grain yield and protein concentration. Large differences were found among tested cultivars for GPC stability, as expressed by the amplitude and the coefficient of variation. Romanian cultivars showed better GPC stability than the tested foreign cultivars. Neither the amplitude of variation, nor the coefficient of variation was correlated with average GPC, indicating possibilities in breeding for both higher and more stable GPC. Based on regressions of each cultivar GPC on average GPC of all cultivars, cultivars could be classified as more responsive to environments that were favorable to higher protein concentration in the grains (such as Capo, Exotic etc), or more able to maintain GPC in less favorable environments (such as Simnic 50, Dropia, Flamura 85, Izvor, Glosa and Lovrin 34). Frequency of GPC value below an accepted minimum, which is important from farmer's point of view, closely correlated with the average GPC (r = -0.847(ooo)), but some cultivars with similar averages had different number of cases below the required level, indicating additional possibilities of progress.