Analysis of bearing behaviors of 'velkopavlovicka' apricot clones

Widely grown cultivars of apricot usually exhibit phenotypic variation among clones that may lead to different bearing potentials. Clone selection is one of the breeding tools that may be used to improve bearing behavior. However, little is known about the basis of the different bearing behaviors among clones of a particular cultivar. Our assumption was that these behaviors could be linked to shoot morphology and demography. This study aimed to analyze the morphology of 1-year-old shoots in five clones issuing from a classical Czech cultivar, 'Velkopavlovicka', belonging to the Hungarian best cultivars group. In 12-year-old trees, branches were described over 3 years and from the second to the fourth orders. In these branches, all annual shoots that developed in a given year were described at the node level and were classified into three types depending on their length. For each clone, the proportion of the different shoot types, the number of flower buds per shoot and per node ( considering central and lateral axillary flower buds), as well as the presence of fruits were considered. The mean number of flowers per shoot was higher in the first observation than in the second, and the largest differences among clones were found for medium shoots. All clones displayed similar within-branch demography of shoot types, but differences were found between years, which appeared related to the tree bearing status. This study confirmed that 'Velkopavlovicka' clones bear most fruits on short or medium-length shoots. It also suggests that fruit load and shoot length influence the regularity of flowering, in conjunction with the shoot type proportion, which also matters at more global scales, such as branches or trees. Our results show that Doc. Blatny, LE-111 and VP-LE-12/2 are more suitable than the other evaluated clones of 'Velkopavlovicka' from an agronomic point of view, although further investigations will be necessary to assess them.