Department of Horticulture and Landscape Architecture

SEMINAR

Mokhles A Elsysy Purdue University Control of Flowering in Apple - Physiology and Management Apple fruit production is highly dependent on flowering frequency. Irregular flowering can lead to biennial bearing. Biennial (or alternate) bearing is a term used in pomology to refer to trees that have an irregular crop load from year to year. Biennial bearing is challenging for the fruit trees industry. For this, overcoming biennial flowering is essential for successful annual production of some high value cultivars that show the biennial bearing phenomenon. Although biennial flowering is disadvantageous in apple trees, selective pruning and crop load manipulation can be used to increase the frequency of flowering buds, however these manipulations produce variable results and are costly. Over the last century many hypotheses were introduced to determine the source of flower inhibition, but hypotheses 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 heavy flowering load and parts with low or no flowering load. Many factors influence apple flowering via affecting the ability of trees to initiate flowering buds annually, such as crop load, bourse length, and seed number. These factors contribute to flowering bud formation via affecting endogenous factors such as growth regulators and expression of flowering genes. Identifying the source of flowering signals will help us to identify their pattern and identify the genes responsible for flower initiation. Furthermore it will help us to have a better understanding of the flowering process in apple. This seminar will explain the interaction between local within spur effects with the systematic whole tree effect that regulates flowering. In addition, we will highlight the dissimilarity in flowering regulation between annual and biennial cultivars. Furthermore, we will introduce the effects of leaf anatomy and leaf gas exchange parameters on flowering habits in annual and biennial cultivars. December 3, 2015 3:30 pm HORT 117 *Seminar will be recorded