Effect of pre-harvest boron application on the incidence of CA-storage related disorders in 'Conference' pears

'Conference' pears are susceptible to physiological disorders, such as brow n heart and cavities if stored in controlled atmosphere (CA) storage with h igh CO2 concentrations. The effect of preharvest foliar sprays of boron (B) on several physiological characteristics and the incidence of CA-related d isorders in 'Conference' pear fruit stored under high CO2 CA-conditions was tested. Several times before harvest, trees of 'Conference' pears were spr ayed with boron. After harvest the fruit were stored at -0.5 degreesC with 5% CO2 + 2% O-2 CA-conditions. During a four-month storage period, the frui t were inspected for physiological disorders and quality characteristics. I n addition, cell membrane permeability, mineral concentration and vitamin C content of the inner cortex of fruit tissue were determined. The results i ndicate that fruit treated with boron did not exhibit any browning disorder s after four months, compared with a high incidence of brown heart in contr ol fruit. In comparison with control fruit, B treatment reduced membrane pe rmeablity at harvest and during storage and increased B and Vitamin C conte nt of inner cortex tissue. The macronutrients: K, Ca, Mg and P, as well as the fruit quality characteristics: firmness, soluble solids, acidity and fr uit colour were not affected. The importance of B on the structure and inte grity of cell membranes and walls, as well as the cellular defence mechanis m in relation to browning disorders is discussed.