Effect of deficit irrigation during oil synthesis period on carbohydrates content in olive hedgerows (cv. Arbequina)

During fruit oil synthesis and accumulation period, fruits are the main carbohydrate sink and water stress may modify the reserve availability for next season development. The objective of this study was to evaluate the effect of deficit irrigation during fruit oil synthesis period on next season carbohydrates content. Experiment was carried out in a super high density olive orchard (Olea europaea cv Arbequina) located in La Puebla de Montalbán, Toledo, Spain (39º 48’N, 04º27’W, 516 msnm). Two irrigation level were applied from the middle August until harvest (First November), when most of the 80% of the oil accumulated on fruits occurs. The control treatment (Non stressed) was irrigated until harvest, trying to maintain the root zone close to field capacity. The Stressed treatment was irrigated with water dosage being reduced to 12% of Non stress treatment. Carbohydrates (soluble sugars and starch) were measured on roots, leaves and stems at the end of winter. Differences on carbohydrate concentration were observed on leaves but not in the reserve organs as roots or stems. Leaves of the Stressed trees presented higher carbohydrates content. These results show the important role of carbohydrates on water stress adaptation by osmotic regulation.