Salinity Effects on External and Internal Morphology of Rose Geranium (Pelargonium graveolensL.) Leaf

Abstract

Salinity is an environmental condition that induces stress on plants especially under high soil salts levels. It limits crop metabolic activities, hampers plant growth and synthesis of secondary metabolites. It also affects osmotic potential in the plant root zone. A complete randomized block design was used to evaluate the effect of salinity applied at 1.6, 2.4, 3.2 and 4.0 mS cm-1 on external and internal morphology of rose geranium (Pelargonium graveolens L.) leaf and treatments were replicated three times. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to evaluate the morphology of the leaf. Salinity levels induced the development of capitate trichome. Abaxial leaf position had the highest number of trichomes than the adaxial leaf position. A strong polynomial (r2=0.97) relationship was found between capitate trichome and salinity. High densities of capitate trichomes were found at a high salinity level. Although the development of asciiform trichome was induced, it was in an insignificant level, trichomes densities are therefore not affected by salinity. It was therefore concluded that rose geranium might have some degree of tolerance to salinity.