Growth traits of five young olive cultivars, grown under different irrigation regimes

Olive is a typical Mediterranean crop, featuring high water stress resistance and adaptation to drought. It has also been reported to be highly responsive to irrigation, both in terms of vegetative growth and yield. The present research was undertaken to provide quantitative data concerning the response of 5 olive cultivars to different irrigation regimes, in an inland hilly area of southern Italy. The experiment was carried out in 1996, on a 6 x 3 spaced drip-irrigated orchard, established in 1992. Five table and double purpose cultivars - Ascolana tenera, Kalamata, Nocellara del Belice, Itrana and Maiatica, the first three yielding fruit in 1996 were tested under four water regimes: TO (rainfed) and T1, T2 and T3 that received a water equivalent of 33, 66 and 100% of estimated crop evapotranspiration, respectively. Irrigation markedly influenced growth behaviour. Trunk diameter was 7.73, 7.60, 6.94, 6.92 cm at the end of 1996 for T3, T2, T1 and TO respectively, with almost no differences between the highest 2 irrigated treatments, and between T1 and the control. Differences in mean shoot length were evident at the end of August between T3 (45.4 cm) and the other treatments - 39.2 38.4, 38.2 cm, for T2, T1 and TO - loosing significance thereafter. Ascolana, Itrana, Kalamata, Nocellara and Maiatica ranked in decreasing order featured the development that concentrated in the second part of the season. Growth analysis parameters were computed and their trends analysed. Simple correlation matrices were calculated to investigate the existence of correlation with yield, for the different phenological phases, to evidence periods of strategic importance in terms of efficiency of water application.