Chilling requirements of ten sweet cherry cultivars in a mild winter location in Chile

Given the marked seasonality of sweet cherry (Prunus avium L.) production, it can be profitable to extend the harvest period and consequently prolong the sales period. Possible solutions for this are the use of different varieties and the relocation of production. The expansion of production into less cold zones has been limited by the chilling requirements of the cherry varieties. Recently, due to the appearance in Chile of new varieties having potential variability in their chilling requirements, a study was initiated to evaluate their productivity and fruit quality. Several replicated field experiments were done in a high density cherry orchard located at the La Palma Experimental Station of the Pontificia Universidad Catolica de Valparaiso. The capacity of sweet cherry buds to overcome endodormancy from exposure to two different chilling hour accumulation cycles was evaluated. The cultivars evaluated were: 'Garnet', 'Burlat', 'Brooks', 'Lapins', 'Bing', 'Newstar', 'Ruby', 'Van', 'Somerset' and 'Celeste'. Of these, seven ('Burlat', 'Brooks', 'Lapins', 'Newstar', 'Ruby', 'Van' and 'Somerset') overcame bud dormancy after being exposed to variable numbers of hours of continuous exposure to 6°C. The same cultivars had higher levels of budbreak under field chilling conditions, and 'Celeste' overcame bud dormancy as well.