Une régie de trois coupes chez le dactyle (Dactylis glomerata L.) en régions agricoles du Moyen-Nord de l'Est du Canada

Abstract

Orchardgrass (Dactylis glomerata L.) has good winter survival in the mid-north agricultural areas of eastern Canada. There is no information on the cutting management to use after the first harvest of orchardgrass under these climatic conditions. The objective of this study was to determine the required interval between harvests following a first harvest at heading stage to optimise the productivity and maintain the persistence of orchardgrass. An interval of 35 d between harvests was sufficient to obtain annual yields of 4 to 6 tonnes of dry matter per hectare. An interval of 28 d between harvests had no negative effects on orchardgrass persistence under our climatic conditions. A second harvest taken 42 d after the first one often had a negative effect on the dry matter yield of the third harvest. Each time this occurred, we observed that the second harvest had been taken after 20 July. Heading dates varied among years. In addition to the growth stage at the first harvest, the date of occurrence of the heading stage should be considered so that the second harvest will be taken before 20 July. Consequently, if heading is delayed in spring, the interval between the first and second harvest must be reduced to take the second harvest before 20 July. Delaying the third harvest had a negative effect on the dry matter yield of the first harvest of the following production year. These results indicate that it is possible to take three harvests before September under the climatic conditions of the mid-north of eastern Canada without affecting the persistence of orchardgrass. Key words: Dactylis glomerata L., orchardgrass, cutting stage, cutting intervals, cutting management, yield