Flowering responses of young olive trees (Olea europaea) to experimental warming during summer and autumn in Northwest Argentina.

MISERERE, ANDREA; SEARLES, PETER S.; FEDERICO, ANA AILÉN ; HERRERA, CARLOS J.; BRIZUELA, M MAGDALENA; ROUSSEAUX, M. CECILIA

Rosario

Congreso; XXXIV Argentinian Meeting of Plant Physiology; 2023

Oliveexpansion into new growing areas and global warming require a better understanding of the effectsof elevated temperature on flowering. This study aimed to assess how warming during summer andautumn affects the timing of flowering and its intensity in two olive cultivars. A field, warming experimentwas conducted in La Rioja, using two year o ld, potted olive trees (‘Arbequina’, ‘Coratina’). Twotemperature levels, a near ambient control (T0) and an actively heated (T+) treatment (+3°C), wereestablished from December to mid May of the 2014 15 growing season in open top chambers (OTCs). Thetre atments were applied during the entire period, early (Dec Feb), or late (Feb to mid May). Additionaltrees located in an adjacent nursery received no temperature manipulation (NM). In spring, the full bloomdate (FB, at least 50% of flowers open) and the flowering intensity (FI; % of lateral buds withinflorescences) were determined visually with weekly observations. The FB date was affected by thetreatment period, but not by the temperature level. In ‘Arbequina’, entire and late trees had later FB da tes(4 6 days) than NM and early trees. In ‘Coratina’, trees from the early , late , and entire periods flowered 2 3days later than NM trees. The FI in ‘Arbequina’ was greater than 60% in NM and T0 trees from alltreatment periods. T+ trees from the early p eriod also had high FI. However, FI was significantly reducedto 10% in trees warmed during the entire or late periods. In ‘Coratina’, the FI was high in the NM and earlytrees, but FI was very low in both T0 and T+ trees from the entire or late periods. T he results indicate thatwarm air temperatures during autumn will likely reduce FI substantially with climate change, even incultivars with relatively low chilling requirements such as ‘Arbequina’ and ‘Coratina’. Thus, limiting oliveproduction in Northwe st Argentina unless more suitable cultivars can be found.