Shoot growth pattern and degree of flower bud differentiation in yield potential modelling in apricot

This study presents results of the analysis of the differentiation degree of flower buds at different stages of growth of the long shoots in apricot. Long shoots are oneyear-old shoots where terminal growth is stopped and continued several times during the vegetation (I-IV). In that way the flower buds are formed at different periods. Histological analysis of the flower buds on different growth flushes shows differences in the degree of differentiation as a consequence of bud positioning on those flushes of growth. Hence, the buds on the first growth flush are the most differentiated, while less degree of differentiation is observed on the buds on the last growth flushes (III and IV). Different degree of differentiation of the buds influences their growth and development in the early spring which represents an important factor regarding adaptation to the given growing conditions and finally affect yielding potential. Namely, buds from the first growth flush are the first to develop in spring and give the least contribution to the yielding potential (13.06-21.35%). Buds from the II and III growth flush, which have the lower degree of differentiation and are developed later compared to the buds of the I growth flush give a larger contribution to the yielding potential (38.02-41.71%). In this paper the degree of differentiation of the flower buds is analysed and realization of the yielding potential of the different flushes of growth on the long shoots in cultivars ‘Hungarian Best’ and ‘Novosadska Rodna’ in the years 2011 and 2012. The influence of the degree of differentiation of the flower buds on their productivity in relation of the position on the different growth flushes can successfully serve as one of the elements for modelling growth and fruit bearing in apricot on the long shoots.