Mechanical stress in the shoot apices of Euphorbia, Lycopersicon, and Pisum under controlled turgor | Mechanical stress in the shoot apices of Euphorbia, Lycopersicon, and Pisum under controlled turgor. [Tomatoes, peas]
1973
G. H. (G. Hussey),
Cuts were made in the surface of the shoot apices of Euphorbia lathyris, tomato (Lycopersicon esculentum), and Pea (Pisum sativum) while they were completely immersed in water or aqueous mannitol at various concentrations, or in near-saturated air. Gaping occurred all over the apical dome of Euphorbia and on the tomato apex at the site of emergence of the primordial bulge. Maximum gaping occurred in near-saturated air and under water, and was progressively reduced with increasing osmotica. It is concluded that the gaping results from tension in the surface cells and is not caused by superficial drying out. No gaping occurred in the axil of the newly formed primordium of the tomato nor anywhere in the apex of the pea. Histological evidence suggests that these tissues are under lateral compression. The mechanical stresses involved are discussed in relation to the morphology of the apices together with existing data on the distribution of cell division during primordia formation.
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