MORPHOLOGICAL AND ANATOMICAL FEATURES OF BLOSSOM END BROWNING (BEB) DISORDER ATTACKING 'ANNA' APPLE FRUITS IN EGYPT

The present study was preformed to reveal some facts about the blossom end browning (BEB) phenomenon in ‘Anna’ apple fruits which causes high economic losses of apple production in Egypt. Mature fruits were harvested from six-year-old trees budded on M.M.106 root stocks and grown in sandy soil in a private orchard. Harvested fruits were immediately stored under room temperature (26±2°C). Fruits were inspected daily up to 10 days to follow up the apparent and histological changes during the incidence of BEB phenomenon. The initiation of BEB which occurred three days after harvesting. It began with changing in peel color to become strong yellow in nearly circular watery spot, with 1-1.5 cm in diameter located aside of the fruit distal end (blossom end). In the fourth day, the attacked area circularly and slowly spread towards the proximal fruit end axis and also towards the fruit core axis to entailed one fourth of the fruit with” dark yellow” color of peel and flesh. The attacked area extended in the same way to cover one third of fruit mass on the eighth day with “grayish brown” color of the attacked tissue. Moreover, the attacked fruit mass which became more spongy and watery was secondary attacked with many fungal and bacterial micro-organisms on the 8th-10th day after harvesting. The microscopic inspection of the attacked tissues elucidated that fruit tissues appeared normal and sound for two days after harvesting. On the third day after harvesting some cells of the cortex tissue are shown with very thin walls, while some others appeared with deformed cell walls. On the fifth day after harvesting, the deformed cells of cortex tissue increased and extended in two axes, those are towards the fruit core as well as towards the proximal fruit end. On the sixth day after harvesting, the transverse section showed scattered group of cells in cortex, which were completely collapsed. The damaged cell walls canceled the individuality of the cells, so that some elliptical grooves and cavities appeared in the cortex. Cell components began to vanish. The results suggested that the deformation of cortex cell walls in the distal part of ‘Anna’ apple fruit is the first step for BEB incidence.