Dormancy index of apple tree buds measured by the single node cutting biological test.

摘要

In the test known as single node cutting biological test, which is widely used for dormancy intensity evaluation of temperate tree fruit buds, one-bud cuttings are placed in a local propitious for their growth and the average shooting time (AST) is directly related to the bud's dormancy intensity. However, AST analysis alone generates not so conclusive results since other factors such as final shooting (FS), shooting velocity (SV), and vigorous shooting final rate (VSR) are also indicators of dormancy. The objective of this work was to reunite these four parameters in a single formula so that dormancy may be more precisely evaluated by a dormancy index (DI). The data used to develop the DI were obtained by testing 1-year-old 'Imperial Gala' apple tree buds. DI was directly proportional to AST and inversely proportional to FS, SV and VSR. Each parameter was multiplied by a constant factor, according to its importance in the dormancy analysis. The general formula is DI=AST.(k.FS+w.SV+VSR)-1. The constant variables k and w must be calculated accordingly to the species being studied. As for apple, they are k=3 and w=2. By using the DI, the dormancy intensity was classified in 5 groups: lack of dormancy (DI <=2); weak dormancy (2 < DI <= 5); moderate dormancy (5 < DI <= 9); intense dormancy (9 < DI <= 14) and deep dormancy (ID >14). For other fruit species, a new DI should be formulated.