Morphological changes during development of cultured citrus explants (Citrus sinensis (L.) Osbeck cv. Shamouti) were observed with a scanning electron microscope (SEM). Prophylls of resting buds, covered with epidermal hairs, were closely appressed until the growth of a new shoot; they then expanded. The addition of 10-5m 6-benzylaminopurine to the medium resulted in the formation of several adventitious buds, surrounded by multiple prophylls, in the axil of the petiole. Abscission of the petiole from the explant involved formation of a separation zone with no evidence of new dividing cells, or active cell division and formation of callus tissue in the abscission zone.
Received for publication June 27, 1977. This research was supported by a grant from the United States - Israel Binational Science Foundation (BSF), Jerusalem, Israel.
The technical assistance of Mr. 1. Giladi is gratefully acknowledged.