|Authors: ||Paul D. Metheney, L. Ferguson, David A. Goldhamer, J. Dunai|
Olive flowering, shoot growth, and quantity of fruit response of mature "Manzanillo" olive trees (Olea europaea L.) subjected to eight levels of irrigation was measured through three seasons, 1990, 1991, and 1992, in California's San Joaquin Valley.
Irrigation levels corresponded to ETo (modified Penman grass reference) crop coefficients (Kc) ranging from 0.16 – 0.85. The 0.65 Kc was the control with differences between treatments of 15 %. Monthly averages of leaf water potential measurements for the three highest irrigation treatments ranged between -0.4 and -0.55 MPa from April through August, implying water stress occurred below -0.55 MPa.
Water stress in the lower Kc's resulted in less shoot growth and earlier bloom periods.
Trees in the four lowest irrigation regimes achieved 50 – 80 % full bloom by 20 May while those in the four highest irrigation regimes averaged 31 % full bloom by 20 May.
The average shoot growth from April through September for the four lowest irrigation treatments was 7.0 cm versus 10.4 cm for the four highest irrigation regimes.
A logarithmic relationship existed between the average number of fruit per tree and the average shoot growth of five shoots per tree.
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