Phenotyping of strawberry cultivars for agronomic performance and disease resistance

Among soft fruit, strawberry is considered one of the most important ones. Mainly praised for its aroma, profitable appearance and good nutritive values, strawberry is also acclaimed for its health promoting characteristics. Most cultivars are very susceptible to fungal diseases, causing drastic yield losses in conventional cropping systems. An environmentally-friendly option is the use of genetic resistance to reduce the application of fungicides. Our study was conducted over two consecutive years. The first year in the region of Ain Aouda on an organic farm, where 10 cultivars were assessed for their horticultural performance and resistance to powdery mildew (Podosphaera aphanis) and grey mould (Botrytis cinerea). The severity index and area-under-the-disease-progress curve (AUPDC) were estimated. The cultivar ‘Victory’ was used as a control for disease resistance and ‘Fortuna’ for agronomic performance. During the second year five new cultivars were added to the collection. The trials were conducted in two regions: Larache farm with a conventional cropping system and Ain Aouda’s organic farm. The results showed differences between cultivars, which were highly significant for homogeneity and firmness, and highly significant for brightness. The interaction of cultivars with the organic cropping system (Ain Aouda) and the conventional cropping system (Larache) was scored. Highly significant differences between the two sites were observed for total production, marketable production and soluble solids. These differences can be explained by the cultivation method, the phytosanitary treatments and the application of fertilizers. The interaction between sites was significant for both total and marketed yield. Botrytis cinerea disease was more severe than that caused by Podosphaera aphanis. Some cultivars had a high UADPC, but a low severity index. The correlation between the variables measured showed an interdependence between AUDPC and marketable production (r=-0.62), thus denoting the negative impact of grey mould on production. The preliminary results of this study showed the interaction of strawberry cultivars with two fungi. The next steps of the study will address the use of genetic markers to improve strawberry molecular breeding for the development of eco-friendly resistant cultivars with improved quality and yield.