Over the last century many theories have been promoted to explain the source of flower inhibition, but these rarely discussed the source of flower promotion. The flower promoting or inhibiting signal seems to be localized in a specific part of the tree because the apple tree could have parts with high flower density and parts with little or no flowers. Many factors influence apple flowering by affecting the ability of trees to initiate flowering buds annually, such as crop load, bourse length, and seed number. These factors likely affect endogenous factors such as growth regulators and expression of flowering genes. Identifying the source of flowering signals will help us to identify pattern of their expression and identify the genes responsible for flowering initiation. This will help us better understand the flowering process in apple.
In this presentation we will explain the dissimilarity in flowering regulation between annual and biennial cultivars and the local effect of fruit weight, seed number, bourse length and leaves on flowering induction. Furthermore, we will explain the effect of leaf anatomy and leaf gas exchange parameters on flowering habits in annual and biennial cultivars.