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a malformation of plant stems by which the stems become flat, ribbonlike, or ribbed. Fasciation is caused by infection by specific viruses, mycoplasmas, bacteria, microscopic fungi, or phytohelminths. The disorder can also be caused by mites or insects or by the effects of ionizing radiation, chemical mutagens, growth stimulators, pesticides, or fertilizers. Other causes are mechanical trauma and the disruption of moisture, light, temperature, or other regimens.
Fasciation is associated with the fusing of stems to one another or of lateral branches with the main shoot, the fusing of several growing points, or the proliferation of a single growing point. The malformation results in deformation and twisting of the stems and abnormal branching of the stems’ apical portion. The time of formation and the distribution of leaves, flowers, and inflorescences are altered. Other effects of fasciation are extreme branching of the inflorescences, an increase in the number of flowers, deformation of the flower owing to an increase in the number of organs that form it, development of a multilocular gynoecium, proliferation of fruits, and a shift in the rhythm of cell division and differentiation. The physiological and biochemical principles behind fasciation have not been established.
Fasciation that affects flowers, inflorescences, and fruits is often beneficial, inasmuch as it is used in the selection of certain agricultural plants, for example, large-grain diploid varieties of buckwheat. The study of fasciation is of considerable value in determining the structural and hormonal principles of plant morphogenesis.
REFERENCESDanilova, M. F. “O prirode fastsiatsii u rastenii.” Botanicheskii zhurnal, 1961, vol. 46, no. 10.
Slepian, E. I. Patologicheskie novoobrazovaniia i ikh vozbuditeli u rastenii. Leningrad, 1973.
E. I. SLEPIAN