Ultrastructure of Eucalyptus grandis * E. uropylla plants cultivated ex vitro in greenhouse and field conditions

摘要

The young and expanded leaf micromorphology and ultrastructure of Eucalyptus grandis * E. urophylla juvenile plants, cultivated in greenhouse and field conditions, were analyzed by scanning and transmission electron microscopy. In greenhouse leaves epicuticular wax needles covered the abaxial and adaxial surfaces. On the adaxial surface, the needles form an atypical arrangement in lines, mainly over the anticlinal wall of epidermis cells. After plant transfer to field conditions, the organization of epicuticular wax was altered forming amorphous layers on the adaxial leaf surface, in contrast to the abaxial surface, which maintained the wax needle cover. In both culture conditions the lamellar cuticle formed on the young leaves surface disappeared during leaf enlargement. The ex vitro environment induced the development of hypostomatic leaves. The dorsiventral organization of greenhouse leaves was replaced by an isobilateral arrangement in field conditions with con##-comitant aerial space reduction. Results suggest that those structural changes may be some of the strategies to avoid excessive plant transpiration during Eucalyptus hybrid plants' acclimatization.