High tunnel cultivation of sweet cherry (Prunus avium L.): physiological and production variables

Use of high tunnels in sweet cherry production is a popular way to reduce rain-induced fruit cracking. However, little information is available for its effects on tree physiology and fruit quality in established sweet cherry orchards. The aim of this study was to evaluate changes in the physiological and production variables of sweet cherry under high tunnels in a Mediterranean type climate in the Central Valley of Chile (35 degrees 1' S, 71 degrees 32' W). In 2017, a trial was conducted in a commercial orchard with the early and highly - productive cultivar combination of 'Royal Dawn' on 'MaxMa 14'. Trees were trained as a Y-trellis, spaced at 4.5 x 2.0 m and drip irrigated with four emitters (each emitter of 4 L h(-1)) per tree. Two treatments of five blocks per treatment were imposed. Treatments were 'covered' = trees under multi-bay Haygrove (R) high tunnels and 'open' = trees under open field conditions (control). The average value of g(s) increased during fruit development but the values under cover were generally 30% higher than in the open. Full bloom occurred 4 days earlier under cover and fruit was harvested 8 days earlier than that in the open and yields were similar (15 kg tree(-1)). Trees under high tunnels received 20% less amount of water than uncovered trees. There were no differences in fruit quality from different canopy layers. Significantly less cracking losses (3%) were observed in covered trees compared with open (19%). No differences in the ratio of leaf area to fruit number (193 cm(2) fruit(-1)) were found between covered and open trees but fruit from covered trees were larger, less sweet and softer in firmness than that from trees in the open. These altered fruit quality attributes should be improved in relation to the target market and the associated requirements for transport and storage. Results indicate that the use of high tunnels for 'Royal Dawn' on 'MaxMa 14' sweet cherry production, in a Mediterranean type climate, reduces susceptibility to rain-induced cracking, advances the time of harvest and increases fruit size.