Effect of Gamma Radiation on the Ripening of Bartlett Pears

Gamma radiation at doses of 300 Krad or more inhibits the ripening of Bartlett pears (Pyrus communis L.). Immediately after irradiation there is a transitory burst of C(2)H(4), which subsequently declines in fruits subjected to inhibitory doses. Ethylene production associated with ripening begins at the same time in unirradiated fruits and those subjected to noninhibitory doses, but the latter produces much more C(2)H(4) at the climacteric peak. Fruits subjected to inhibitory doses produce low levels of C(2)H(4) unless subjected to exogenously applied C(2)H(4), whereupon they produce enough of the gas to induce ripening in unirradiated fruits.Pears subjected to 300 and 400 Krad of gamma rays did not ripen even when held in a flowing atmosphere containing 1000 ppm of C(2)H(4) for 8 days at 20 degrees . It is concluded that the action of gamma rays on Bartlett pears involves both an inhibition of C(2)H(4) production and a decreased sensitivity of the fruit to the ripening action of the gas. Ripening of Bartlett pears is inhibited by gamma radiation only when applied to preclimacteric fruit.