Characterization of the Influence of Moderate Temperatures on Rest Completion in Peach

Abstract

The chilling enhancement effect of moderate temperature (15°C) on rest completion in ‘Redhaven’ peach was verified and observed only when the moderate temperature occurred followed exposure to chilling temperatures. Chilling efficiency rose with temperatures between 0° and 8° if no moderate temperatures were interspersed. Although 0° was an inefficient chilling temperature, cycling between 0° and 15° resulted in as efficient bud rest release as 6°. The most efficient moderate temperature level was 13°, and the effect of moderate temperatures on rest completion seemed to increase when received during the latter stages of rest. Leaf and flower buds reacted similarly, although the reaction of the former was more prominent. A two-step scheme is proposed for the effect of temperature on bud rest. The first step involves the conversion from the unchilled to the chilled state by chilling temperatures. This stage can be reversed by high temperatures. The second stage is not reversible and involves the conversion by moderate temperatures of the unstable intermediate formed by step 1 to a stable material, which, when accumulated to a certain level, will result in rest completion.