EFFECT OF NAA AND GA(3) ON LEAVES AND GLANDULAR TRICHOMES OF ORIGANUM X INTERCEDENS RECH - MORPHOLOGICAL AND ANATOMICAL FEATURES

The effect of the growth regulators naphthalene acetic acid (NAA) and gibberellic acid (GA(3)) on Origanum x intercedens was investigated morphologically and anatomically. Leaves treated with NAA underwent a reduction in blade surface area, while simultaneously the amount of the mesophyll increased significantly. Chlorophyll content was less than that of the control leaves. NAA further increased the density of the glandular trichomes (peltate) on both leaf surfaces as well as the size of the secretory head of the trichomes. The epidermal cells radially surrounding the foot cell of the trichomes increased in size and number. The developmental pattern of glandular trichomes was not affected by NAA. GA(3)-treated leaves exhibited a great decrease in size and thickness. Leaf chlorophyll content was reduced with respect to the control leaves. GA(3) application further resulted in a decrease of the density of glandular trichomes on both leaf surfaces. The secretory head of the trichomes became larger in the populations of the upper leaf surface and smaller in those of the lower. No change was observed in the developmental pattern of the glandular trichomes.