EFFECT OF BORON APPLICATIONS ON PHYSIOLOGICAL DISORDERS IN ‘CONFERENCE’ PEARS DURING CA-STORAGE

Under particular CO₂ levels in controlled atmosphere (CA) storage ‘Conference’ pears are susceptible to physiological disorders, such as brownheart and cavities. The effect of preharvest boron sprays on several physiological parameters and on the subsequent occurrence of brownheart in pears stored under high CO₂ in CA, was tested. Trees of ‘Conference’ pears were sprayed with boron several times before harvest. After harvest the fruit was stored in CA (5% CO₂, 2% O₂) at –0.5°C. During the 4-months storage period, the pears were rated for physiological disorders and the permeability of cell membranes, mineral concentrations, vitamin C content and fruit quality parameters were determined. The results show that brownheart symptoms appeared in control fruit already after 2 months’ storage. On the other hand, fruit treated with boron did not exhibit any brownheart disorder. Boron treatment reduced membrane permeability well in advance of the appearance of browning symptoms in control fruit, and increased boron and vitamin C content, without affecting macronutrient levels and other fruit quality parameters. The importance of B for the integrity of membranes and for cellular defence mechanisms is discussed.