EFFECT OF NAA AND GA(3) ON LEAVES AND GLANDULAR TRICHOMES OF ORIGANUMX 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 mo rphologically and anatomically. Leaves treated with NAA underwent a re duction in blade surface area, while simultaneously the amount of the mesophyll increased significantly. Chlorophyll content was less than t hat of the control leaves. NAA further increased the density of the gl andular trichomes (peltate) on both leaf surfaces as well as the size of the secretory head of the trichomes. The epidermal cells radially s urrounding 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 thic kness. Leaf chlorophyll content was reduced with respect to the contro l leaves. GA(3) application further resulted in a decrease of the dens ity of glandular trichomes on both leaf surfaces. The secretory head o f the trichomes became larger in the populations of the upper leaf sur face and smaller in those of the lower. No change was observed in the developmental pattern of the glandular trichomes.