Chilling injury and drought resistance of 5 varieties of Olea europaea L. cultivated in Patagonian Steppe

ARIAS NADIA; BUCCI SANDRA; SCHOLZ FABIAN; GOLDSTEIN GUILLERMO

Luxemburgo

Seminario; 9th Plant and Cold Hardiness Seminar; 2011

Temperature and drought are the most important factors that limit the distributions of many crops. Olive tree (Olea europaea L.) is commonly growing in the Mediterranean where prolonged droughts may occur during the vegetative period. This species has developed a physiological mechanisms to tolerate drought and resist low temperatures. During recent years the increasing demand of olive oil has expanded the cultivation of olive into geographical zones at higher latitudes. Moreover, cold autumns, which slow down fruits maturation process, improve the quality of olive oil, and this has led to olive tree been cultivated where there is a recurrent danger of frost. We evaluated sensitive to low temperatures and resistance to drought in 5 varieties of olive: Arbequina, Manzanilla Californiana, Frantoio, Changlot Real y Hojiblanca during summer in Patagonian steppe (45º 47’S, 67º 30’W). Summers are characterized by long dry periods and minimum absolute temperatures that can decrease to 2°C. Two- years old- plants were grown outdoor in 20-dm3 pots (one plant per pot) filled with a mixture of clay and sand soil irrigated bi- weekly. Electrolyte leakage method was used to evaluate cellular damage of mature leaves and determine the LT50 that is the temperature at which 50% of the total ion leakage was measured. Osmotic potential at turgor loss point, relative water content at turgor loss point (RWCTLP), bulk elasticity modulus and solutes content (Ns) were estimated from pressure-volume curves by 4 leaves per variety. Manzanilla Californiana was the variety that show highest values of LT50 (-2°C), RWCTLP (71.92%) y bulk elasticity modulus (4.17MPa) while Hojiblanca was the variety that show lowest values of LT50 (-5.8°C), RWCTLP (52.14%) y bulk elasticity modulus (2.03MPa). The water potencial at turgor loss point was higher in Manzanilla Californiana than in Hojiblanca (-4,09 MPa, -4,74MPa respectively). Active osmotically solutes were lower in Manzanilla than in Hojiblanca (0,34mosmol.g-1, 0,43mosmol.g-1respectively). Arbequina, Frantoio and Changlot Real show intermediate values from those variables. The temperature at which 50% of the total ion leakage was measured, reflecting a 50% loss in cellular intactness was positively correlated with water potencial at turgor loss point(R2=0.85,p menor a 0.05) and active osmotically solutes content (R2=0.86,p menor a 0.05). Results indicate that Hojiblanca could be the most resistance variety to low temperatures and long periods of drought during Patagonian summer. This variety presented cells that lost the cellular intactness at lowest temperatures. High solutes content found in Hojiblanca could protect membrane against chilling injury. In addition, low water potencial at turgor loss point could allow to this variety decrease minimum leaf water potentials to continue extracting water from drier soils within loss turgor .Results suggest that Hojiblanca could maintain the integrity of the membrane plasmatic and continue growth under desfavorable conditions.