Comparative Histology of Naturally Parthenocarpic, Hormone-Induced Parthenocarpic, and Caprified Fig Syconia

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Abstract
Histological comparisons were made of the following fig syconia sampled 3 times during the growth period: (a) naturally parthenocarpic Kadota, (b) caprified Kadota, (c) parthenocarpic Calimyrna induced by gamma-(indole-3)-n-butyric acid (IBA), (d) parthenocarpic Calimyrna induced by para-chlorophenoxyacetic acid (PCPA), and (e) caprified Calimyrna. In addition to differences in epidermal cells and thickness of the cuticle covering the various tissues in the syconium, the thickness of the cortical parenchyma tissue and the number of cell layers contained in it were greater in both induced parthenocarpic Calimyrna and naturally parthenocarpic Kadota syconia than in caprified syconia. The characteristic thought to be responsible for the superior canning qualities of the Kadota var. is 6-7 layers of cells in the peripheral region of the cortex which were identified as collenchyma. No differences in size or development of laticiferous ducts and vascular bundles were noted among the various types of syconia examined. In general, the development of the exocarp, mesocarp, of achenes in parthenocarpic syconia was less than in achenes of caprified syconia. In caprified and naturally parthenocarpic syconia, the endocarp of the achenes sclerifies. The endocarp in PCPA-induced parthenocarpic Calimyrna syconia did not sclerify but remained parenchymatous. Endocarp tissue was totally lacking in IBA-induced parthenocarpic Calimyrna syconia. The integuments and nucellar tissue collapsed, and there was no embryo or endosperm development in achenes of parthenocarpic syconia.