Growth Responses From Whole Fruit and Fruit Halves of Lemon Cultured in Vitro

Abstract

A comparative growth study was conducted on juice vesicles cultured in the form of various fruit explant types (equatorially bissected fruit halves, longitudinally bissected fruit halves, one‐eighth sections of fruit, one‐quarter sections of fruit, whole carpel segments, 2 or 3 mm thick equatorial slices of fruit, and 1 cm2 fruit endocarp pieces) from 15 mm diam Citrus limon (L.) Burm. f. cv. Eureka lemons. Juice vesicles within equatorial fruit halves produced the least amount of callus. Furthermore, these juice vesicles grew similarly to juice vesicles occurring in the tree grown fruit. A study of cultured equatorial fruit halves using 10–45 mm diam lemons was then conducted. Fruit half cultures containing juice vesicles could be readily established from 15–45 mm diam lemons. Vesicles from 10 mm diam fruit halves, however, invariably produced callus. Vesicles cultured within fruit halves produced proportionately less callus as their fruit diam increased. Juice vesicles cultured in 15–30 mm diam fruits lost their original green color and turned opaque as they matured (i.e., after 3–6 months in culture). A method is also presented, whereby whole lemon fruits can be established and maintained in vitro. Lemons, 35–45 mm in diam, were the best explant sources for establishing whole fruit cultures. Juice vesicles in whole fruit cultures may remain viable for up to 8 months in culture.