Donna A Minott* and Heather A Brown

Abstract: Leaf oil from fruiting female and non-fruiting male Pimenta dioica (L.) Merr. trees, were analyzed by GC. Oil yields from male pimento trees (2.13%) were typically lower than that for female trees (2.67%). Non-fruiting and fruiting trees contained the same volatile components with different relative abundances. The composition of eugenol (p< 0.01), and myrcene, α-phellandrene, γ−terpinene, terpinolene and α-thujene (p< 0.005) were significantly different in the female versus the male pimento trees. Characteristic monoterpenoid profiles were observed for the fruiting and non-fruiting pimento trees which could be used for the early prediction of the berry bearing ability of pimento trees.

Jamaican allspice (pimento: <i>Pimenta dioica</i> (L.) Merrill) is reported to account for about 70% of the world trade. It is rated as a superior product because of its higher oil content, richer flavor and color and the uniformity of the berries (1–2). The chemical composition of the berry oil and the leaf oil, which are both aromatic, has been the subject of several studies (3–11). Allspice is the major spice produced in Jamaica where commerce in pimento products is limited to the berries and the leaf oil. <i>Pimenta dioica</i> is indigenous to Jamaica and is widely distributed across the island in stands resulting from natural propagation. These groves consist of equal proportions of fruiting and non-fruiting or barren trees (12–14). There are, however, a few orchards cultivated with approach-grafted fruiting trees. The pimento tree functions as a dioecious plant (14–15). Each grove requires a limited number of “male” or non-fruiting trees for effective pollination. In order to maximize the commercial production of pimento, it is preferred that the amount of barren trees in the groves be minimized. Traditionally differentiation of the “male” pimento trees has been based on examination of the flowers and productivity of the trees after several years. Flowers from fruiting or “female” and non-fruiting <i>P. dioica</i> trees, reported to have a hermaphrodite structure, do exhibit some differences and can be expertly distinguished. “Female” flowers have approximately 50 anthers per flower and will produce pollen that seldom germinates while “male” flowers have twice the number of anthers and the pollen produced germinates readily. Berries are rarely obtained from “male” flowers and these are often malformed (and one-seeded) but normal twoseeded fruits are commonly formed from the “female flowers” (14). Flowering is dependent on favorable conditions and may not begin until five to ten years after planting. Once flowering is initiated, older non-fruiting trees will blossom profusely but fail to produce many berries (16).