engleski

Stability of grain yield and grain protein content in winter wheat under high and low nitrogen fertilization

This study was carried out in order to determine stability of grain yield (GY) and grain protein content (GPC) in nineteen wheat cultivars grown at reduced (80 kg N ha-1 - N80) and optimal nitrogen (N) fertilization (180 kg N ha-1 - N180). The experiment was conducted in eight environments during three growing seasons using randomized complete block design with two replicates. The stability of the traits was estimated by the coefficient of linear regression (b), variance of the mean square deviations from regression (MS-DEV) and the AMMI model for each level of N fertilization. At both N levels a wide range of mean values of GY, b and MS-DEV was found and the results indicated different stability of the studied genotypes. Because of high value of GY, b about 1.0 and because of the below average MS-DEV value, cultivar Liberta proved as the most stable for GY at N80, and cultivars Mihelca and Liberta at N180. For GPC, the most stable cultivar at both N levels was Aura. The biplot of the first two IPCs identified at least two sub-regions among the locations and showed different influence of the environment on the studied traits of individual genotypes at both N levels. Because of high correlations between reduced and optimal N fertilization levels for GY (0.94**) and GPC (0.91**), the selection for high yield and protein content should be performed not necessary at both fertilization levels. Correlation for b between N80 and N180 for GY and GPC was r=0.57* and r=0.49*, indicating a significant impact of N fertilization on the genotype stability estimates. The above mentioned cultivars could be used as a good source for the development of new, high yielding, top quality and stable genotypes.

winter wheat ; nitrogen ; yield ; protein ; stability ; AMMI

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