Effect of Cultivar and Nitrogen Fertilizer on Agronomic and Quality Traits of Durum Wheat under Organic Management

Quantitative performance as well as product quality traits among a group of durum wheat cultivars developed and selected in different eras from 1915 to 2003 were examined in an south Italian growing region under organic management. Experiments were conducted over four years. Fertilization treatments included the application of 80 kg organic nitrogen (N) fertilizer and fertilization by only the N residue from leguminous pre-crop. Genetic, agronomic and environmental effects for the investigated traits and significant interactions between factors were found. Application of organic N fertilizer increased grain yield and protein concentration, the mean increase compared to the treatment without applied fertilizer was 14.8% and 12.0%, respectively. Moreover, a significant improvement of gluten quality was observed for higher N availability. Significant cultivar by treatment interactions were observed for all quality traits. Cultivars significantly differed in grain yield and semolina protein content; mean values ranged from 2.54 to 3.50 t/ha and from 10.83 to 11.91% d.m., respectively. Modern cultivars showed the highest values. Although, significant cultivar by environment interactions were detected for agronomic and quality traits, cultivars with a stable high performance in regard to grain yield and semolina protein could have been identified. These results evidenced different adaptability of "old" and "modern" cultivars to organic production and identified only one of the "modern" cultivars as suitable to use organic nutrients in order to achieve high grain yield and quality.