Caractéristiques de la dormance des bourgeons du pommier dans les régions à hiver doux

Abstract

Evolution and characteristics of apple bud dormancy in mild winter conditions. In order to study bud dormancy in mild winter climate, the evolution of bud bursting capabilities was investigated, using the « one-node-cutting test », during three successive years. The buds were sampled from Golden delicious apple trees grown in the region of Meknes (Morocco), where now and then abnormal bud burst occurs. The made-up graphs of mean bursting time display a fi rst phase of bud inertia, weak and temporary, of correlative origin, but variable from year to year. This is followed by a peak of true dormancy, wich appears fi rst induced and afterwards removed by the chilling temperatures from november to march. The bud break disorders result thus from the combined effect of a high initial inertia, linked to the previous growth conditions, and a short period of chilling. In fact, the very cause of the disorders is less the insuffi cient chilling avalaible than the double action of these low temperatures that partly increase at fi rst the depth of dormancy before starting to eliminate it.

Keywords

• Apple tree
• bud dormancy
• mild winter
• correlations
• chilling temperatures