Fig. 6.

Effect of hypocotyl heat-girdling on phellogen and aerenchymatous phellem (AP) formation. Soybean seedlings were grown under drained soil conditions until unifoliate leaves were fully expanded. Heat-girdling of the hypocotyls was performed 1.5 cm above the soil surface, following which seedlings were grown under either drained soil (A) or waterlogged (E) conditions for 7 d. (B) and (F) are higher magnification images of the heat-girdled positions shown in (A) and (E), respectively. White arrowheads indicate the position of heat-girdling. Cross-sections were taken above (C, G) and below (D, H) the point of heat-girdling. Scale bars = 2 cm (A, E), 0.5 cm (B, F), 500 µm (G) or 200 µm (C, D, H).