EFFECTS OF ROOTSTOCK ON FRUIT QUALITY AND POSTHARVEST BEHAVIOR OF 'MARSH' GRAPEFRUIT

Our objective was to determine the effects of rootstock on fruit quality and postharvest behavior of 'Marsh' grapefruit. We sampled grapefruit grown on sour orange, Carrizo citrange, Smooth Flat Seville, Swingle citrumelo, US-812 and Cleopatra mandarin rootstocks grown in replicated plots in a commercial grove in Martin Co., Fla. Fruit sampled from trees on each root­ stock were analyzed at the time of harvest for standard fruit quality attributes (fruit size, % juice, Brix, and acidity). Fruit were stored at 5 °C for 5 weeks and then transferred to 20 °c, at which time they were rated for chilling injury (Cl). Samples of fruit were again analyzed for the fruit quality parameters follow­ ing storage. Rootstock had significant effects on all attributes measured with the exception of juice content. Fruit grown on sour orange rootstock developed significantly more Cl than did fruit grown on the other five rootstocks. Fruit grown on Carrizo developed the least amount of Cl. The results confirm that root­ stock has significant effects on grapefruit quality, and it may be important to consider rootstock when making decisions re­ garding postharvest handling of the fruit.