Productivity of olive trees with different water status and crop load.

摘要

A field experiment was conducted over two growing seasons to determine the combined effect of crop load and irrigation on yield components of olive trees (Olea europaea L. 'Leccino') planted at 6 m x 3.8 m in a sandy-clay soil. Different crop loads were established by manual thinning of fruits. Drip irrigation was managed to maintain pre-dawn leaf water-potentials (PLWP) within the following ranges: (i) higher than -1.1 MPa (FI; fully irrigated); (ii) between -1.0 and -3.3 MPa (DI; deficit irrigated); or (iii) below -1.2 MPa, but not lower than -4.2 MPa (SI; severe deficit irrigated). The irrigation period lasted from 6-16 weeks after full bloom (AFB) in 2003, and from 5-19 weeks AFB in 2004. In 2003, full bloom was on 26 May; in 2004, it was on 3 June. Neither irrigation regime nor crop load affected flowering or flower quality the following Spring. The combined fruit yields [on a fresh weight (FW) basis] over both years in SI and DI trees were 49.0% and 81.6% of FI trees, respectively. The oil yields of SI and DI trees were 52.5% and 81.2% of FI trees, respectively. Fruit FWs in FI trees were greater than those of DI or SI trees at 8 weeks AFB. At harvest, FI trees bore the largest fruits, and SI trees the smallest fruits. The FWs of individual fruits at harvest in the FI and DI treatments decreased as crop load increased, but no such relationship was apparent for SI trees. The oil content of the mesocarp increased as PLWP increased from approx. -3.5 MPa to -1.5 MPa. The oil content of FI trees at harvest decreased from 53.1% to 45.7% dry weight as fresh fruit yield increased from 5-25 kg dm-2 trunk crosssectional area. However, crop load did not have any effect on the oil content of the mesocarp in DI trees. Fruit maturation was delayed by irrigation. Maturation index also decreased (indicating delayed maturation) as the crop load on FI or DI trees increased, but did not vary with crop level in SI trees..