S01 - Session O9 - II - Phenotyping and genotyping of strawberry cultivars for agronomic and disease resistance traits

Authors: Kawtar Ziane *, Mustapha Arbaoui, Noureddine Chtaina, Abderrakib ZAHID, Lamiae Ghaouti

Among soft fruits, strawberry ( Fragaria x ananassa ) is considered as one of the most important ones. Mainly praised for their aroma, profitable appearance and high nutritive values, strawberries are also acclaimed for their health promoting characteristics. In Morocco, the area cultivated with strawberries increased from 750 ha in the 1990s to 3537 ha in 2019. However, the varietal portfolio is very narrow as 78% of the cultivated areas is dominated by 5 varieties. Most of those are very sensitive to fungal diseases, causing drastic yield losses in conventional cropping systems if not controlled and thus require the extensive use of several pesticides in nurseries and the field. An environmentally friendly option through the use genetic resistant is highly valuable. This study, part of the MED-BERRY project within the PRIMA program led at the national level by the Agronomic and Veterinary Institute Hassan II, aims to reduce the use of pesticides in strawberry cultivation and to improve pest management by identifying genetic resistance. Regarding the latter, a study was conducted over two consecutive years. In the first year in the region of Ain Aouda in an organic farm, ten cultivars were assessed for their qualitative and quantitative performances and resistance to powdery mildew ( Podosphaera aphanis ) and gray mold ( Botrytis cinerea ). The severity index and Area Under the Disease Progress Curve (AUPDC) were estimated in a comparison with the refrence cultivar 'Victory' as a control for resistance to both diseases. In the second year 5 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 very highly significant differences between cultivars for consistency and firmness, and a highly significant difference for shine. The interaction of cultivars with the organic cropping system (Ain Aouda) and the conventional cropping system (Larache) was scored, showing highly significant differences between the two sites for total production, marketable production and sugar level. These differences could be attributed to the cultivation method, the phytosanitary treatments and the application of fertilizers. The interaction between sites is significant for both total and marketed yields. The highest yield was observed for cultivar AN131362 (1.037.20 g/plant) at Larache (year 2), while did not perform the same at the organic farm. It was observed that the attack of Botrytis cinerea was more severe than that caused by Podosphaera aphanis , but some cultivars having a large progression area but low severity index for botrytis. The correlation between the variables measured showed an interdependence between AUDPC and marketable production (r = -0.62), which confirms the negative impact of gray mold on production. The preliminary results of this study enabled the characterization of a collection of strawberry cultivars for their interactions with two fungi. The next steps of the study will address the use of genetic markers to improve strawberry molecular breeding to develop eco-friendly, better yielding resistant cultivars.