Irradiation-induced lenticel discolouration in 'B74' mango fruit is modulated by ripeness

摘要

As a disinfestation treatment, irradiating unripe 'B74' mango can result in severe Irradiation-Induced Lenticel Discolouration (IILD). We tested the hypothesis that 'B74' fruit sensitivity to IILD would reduce as fruit ripen such as to mitigate skin damage. In two growing seasons, 'B74' fruit were sampled from five commercial farms, held for periods of 2-12 d at 20 degrees C, treated with gamma-irradiation at various doses from 0 Gy to 800 Gy, and assessed for external quality up to the ripe stage. Regardless of dose, irradiating ripening fruit at similar to 70% yellow skin reduced IILD severity on the ripened fruit by 36-47% compared to irradiating unripe green mature fruit at similar to 10% yellow skin. Irradiation of ripening fruit at 300-800 Gy consequently resulted in 74-100% marketable fruit at ripe compared to 5-59% for irradiation of the green mature fruit. Irradiating ripening fruit also minimised delays in loss of green skin during ripening. 'B74' fruit sensitivity to IILD decreases as fruit ripen and so delaying gamma-irradiation until the fruit have partially ripened may be a commercially viable option to reduce quality loss due to IILD. However, fruit would need to be marketed quickly to compensate for a shorter post-treatment shelf-life.