PERFORMANCE OF DURUM WHEAT VARIETIES (TRITICUM DURUM Desf.) UNDER CONVENTIONAL AND ORGANIC AGRICULTURE

Summary

Field experiments were conducted for four years to determine the effects of organic and conventional systems and fourteen varieties (nine old and five improved) on growth, yield and quality of durum wheat crop. The experiments conducted at two sites (low semi-arid and higher semi-arid) were laid out in a split-plot design with four replicates. Studied parameters included (i) grain yield, (ii) technological and nutritional quality of the whole grain, dry matter, specific weight, proteins, amino acids, mineral content, gluten and baking strength.
Results of the agronomic traits indicated that grain yield is on the average lower under organic cultivation compared to conventional methods (2.32 and 2.98 t/ha SEM=0.18 qx/ha respectively). However, varieties performance under this environment changed in dry year. Data analysis indicated high production potential of some varieties such as Khiar, Ben Bechir and INRAT69 (2.47, 2.46 and 2.44 t/ha respectively) under organic farming method. INRAT69 was found stable for grain yield under organic farming with low coefficient of variation (33 %) and a linear regression coefficient close to one (bi=0.94). Khiar and Ben Bechir varieties, identified for organic cultivation, were unstable.
Results of the technological and nutritional quality were influenced by the cultivation method. The organic method affected positively proline contents (1.154 vs 1.146 g/100g of FM) and cystéine (0.216 vs 0.186 g/100g of FM) and gluten index which is responsible for the rheological properties of dough (64.73 vs 61.46 %). Contrary to the organic method, grain protein content is better in the conventional method (13.9 vs 13.5 %/MF, ESM=0.008 %/MF).
Organic cultivation of INRAT69 variety was found to be associated with high nutritional and technological quality parameters such us grain weight, dry matter, total amino acids content and gluten index.
Regardless of the cultivation method, results showed that old varieties Badri, Jnah Khortifa and Hamira have high protein and total amino acids content (> 16 %/FM and > 14.5 g/100g FM, respectively). These varieties should be considered by breeders in selection and breeding programs of durum wheat for organic farming.
Based on these results, only INRAT69 variety could be potentially used in organic agriculture not only because its stable yield, but also because of its higher technological and nutritional quality. This variety could also be adapted for manufacturing organic pasta and couscous.