Experimental warming during autumn and winter decreased freezing resistance in Olea europaea plants

NADIA ARIAS; GISELA PARRA; ANDREA MISERERE; VIRGINIA CORTES MOLINA; ROCIO ARGAÑARAZ; PETER SEARLES; SANDRA BUCCI; M. CECILIA ROUSSEAUX

Simposio; IX International Olive Symposium; 2023

Global climate change is likely to increase mean average temperature, reduce precipitation and alters timings, frequency, and intensity of frost events. Warmer temperatures during the autumn and winter will potentially increase growing season length and could expose plants to low and freezing temperatures, increasing their risk to suffer frost damage. The objective of this study was to determine leaf frost resistance and vegetative growth of Olea europaea exposed to experimental warming. A field experiment with two temperature levels was conducted using well-irrigated, potted olive trees (cvs. Arbequina, Picual) grown in open-top chambers for two periods of 60 days during the autumn or winter. The temperature levels were a near-ambient control (OTC0) and a heated (OTC+) treatment (+4 °C). During autumn and winter, leaf cell membrane damage (LT50) of cvs. Picual and Arbequina grown in heated treatments was higher (around 2°C) than control treatments. For example, cv. Arbequina plants grown inside OTC+ during the autumn exhibited LT50 values of -7.12 °C ± 0.67 and inside OTC0 the values were -9°C ± 0.55. During the winter we found a negative and linear correlation between late-season shoot elongation (cm) and LT50 (y= 0.756x-9.67, R2=0.90). Olive plants that exhibited lower values of leaf LT50 were those with less shoot elongation. The results showed that the exposure to warming temperatures decreased olive freezing resistance, suggesting that global climate change could limit olive crop acclimation to low temperatures and decrease survivability under freezing events.