Yield and quality of two rainfed olive cultivars following shifting to irrigation

Six years old Frantoio and Leccino olive plants were subjected to different water regime for two years to assess yield and quality performance in response to the onset of irrigation. Irrigated plots received 33, 66 and 100 % of Etc - 173 and 212 mm, in 1999 and 2000 respectively - while no water was applied to treatment 0. Little rain occurred throughout the summer of 2000 season and mean air temperature was higher than 1999. Midday stem water potential of non irrigated plants was only slightly decreased, however. Stem diameter and canopy volume of Frantoio were enhanced by irrigation, while Leccino only showed a response in terms of the latter parameter. The response of both vegetative and reproductive parameters grouped in two classes, with the rain fed control not different from 33 and treatment 66 and 100 almost identical. Yield to water supply relationship was curvilinear in the first year, with little yield increase in response to 100. In 2000, a non-bearing year, yields were lower and the trends were linear, with a gentle slope. Under treatment 100, Frantoio out yielded Leccino by 18% in 1999, while Leccino featured a better yield in 2000. WUE ranged between 0.87 and 0.24 in 1999 and between 0.76 and 0.31 in 2000, with Frantoio featuring the higher figures in 1999 and Leccino in 2000. Irrigation efficiency peaked in correspondence of 66 treatment for Frantoio and treatment 33 for Leccino. A complete replacement of water loss by plant is to therefore be recommended only in situations of unrestricted water supplies, and Leccino should be preferred when water is costly or scarcely available. Total polyphenolic content was modified by irrigation, to an extent not capable of significantly affecting oil storage capacity.