Factors affecting leaf crinkle in Aphelandra squarrosa Nees ʻDania ̓

Abstract

Selected flat leaved plants of Aphelandra Squarrosa Nees 'Dania' were subjected to chemical, environmental and morphological studies to determine the relationship of these factors to the development of leaf crinkle. Application of chlorotetracycline and tetracycline both as bare root soaks and drenches at 100 ppm and 500 ppm had no affect on the control or evident submission of leaf crinkle. Silver nitrate at 10, 60 and 240 ppm and gibberellic acid as foliar sprays did not stabilize or control the problem. Nitrogen at 400 ppm did reduce the amount of leaf crinkle under light intensities 5.2, 16.4 and 86.4 klx. Light intensities and quality were the most effective treatments in reducing the severity of crinkle. Plants under the 5.2 klx and under blue filtered light had similar crinkle reduction. Electron microscopy studies of the crinkled leaves revealed phytoferritin deposits and an increase of osmiophilic lipid globules usually associated with diseased leaves. No phytoferritin and less osmiophilic lipid globules occurred in the non-crinkled leaves. A pathogen was not identified however, but this does not preclude its presence alone or in combination with other factors influencing crinkle.