Long-term evaluation of growth and production of olive cultivars in super high-density orchard under cold-weather conditions

Hedgerow olive orchards are being established in all olive-producing countries. Little information is available, however, concerning adaptation of olive cultivars to cold conditions. For this reason, nine olive cultivars were trained in hedgerows and evaluated during nine years in the cold area of central Spain (Toledo). Three of them ('Arbequina', 'Arbosana' and 'Koroneiki') are the most widely cultivated in hedgerow orchards. 'Cobrancosa', 'Cornicabra' and 'Manzanilla cacerena' are cultivated in cold weather conditions, and 'Sikitita' is a new cultivar, so far evaluated only in warm areas. Vegetative growth (tree height and trunk diameter) was measured annually until individual hedgerows were formed. In most cultivars, hedgerows that occurred by the 5th year after planting. At that time, hedgerow architectures were described. Fruits were machine-harvested from the 3rd year. 'Koroneiki' showed the highest growth rate from the first year and very few trees were damaged by harvesting. In the 7th year, the most vigorous cultivars were 'Koroneiki', 'Arbequina' and 'Cornicabra' and the least were 'Arbosana' and 'Sikitita'. Regarding hedgerow architecture, 'Koroneiki' and 'Arbosana' hedgerows were narrow while 'Arbequina' and `Manzanilla cacerefia' were wide. Neither vegetative growth nor hedgerow size were related with oil production. After 9 years 63% of the 'Cobrancosa' trees were severely damaged by harvesting. 'Arbosana', 'Koroneiki' and Arbequina' produced the greatest number of fruits and most oil. After 7 years they remained the most productive cultivars but by then oil yields of 'Cornicabra' and 'Sikitita' were comparable. These latter two cultivars produced fewer fruits of higher oil content. 'Manzanilla cacerefia' and 'Cobrancosa' are not recommended for hedgerow orchards because of high alternate bearing, low production and susceptibility to damage during machine harvesting. 'Cornicabra' and 'Arbosana' are of questionable use in cold conditions because of high susceptibility to Pseudomonas savastanoi. Considering all agronomic aspects, 'Koroneiki', 'Sikitita' and 'Arbequina' can be recommended for hedgerow production in similarly cold environments.