Analysis of bearing and branching behavior of two apricot cultivars

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The nature of axillary production along shoots is one of the main factors influencing both vegetative and reproductive growth in apricot. This study aimed at analyzing the morphology and branching pattern of one-year-old shoots of 'Velkopavlovicka' cultivar in comparison with 'Bergeron'. 'Velkopavlovicka' is a classical, medium vigor, Czech cultivar which has naturally a spherical crown. In twelve-year-old trees grafted on apricot seedlings and pruned to an open vase, lateral branches were described from the second to the fourth orders. Each shoot was described as a sequence of metamers, and for each metamer the fate (latent, vegetative or floral) of the central bud as well as the number of associated flowers were noted. The presence or absence of development of axillary shoots from vegetative buds was also considered. A hidden semi-Markov chain was built for each cultivar on the basis of the sample of bivariate sequences corresponding to the two observed categorical variables, pooling all one-year-old annual shoots whatever the year. Both cultivars could be characterized by a similar organization in zones, but with different probabilities of occurrence of the median flower bud zone as well as by different mean number of central and associated flowers within this zone. Cultivar 'Bergeron' proved to be more floribund than 'Velkopavlovicka'. Moreover, they revealed biennial bearing in Central European conditions, but different reasons could be responsible for this behavior depending on the cultivar.