The in vivo growth and development of micropropagated Elatior begonias (Begonia x hiemalis): II. Study on the effect of chlormequat and ancymidol

Abstract

Micropropagation is an efficient means of producing pathogen-free Elatior begonias. However, the growth of the micropropagated plants can be too luxuriant, flowering is often delayed and the root collars remain thin, all unwanted growth habits in commercial production. To study the effect of growth retardants, an experiment was arranged in spring 1987, in which chlormequat and ancymidol were used on the micropropagated Elatior begonia ’Afrodite Limelight’. Both growth retardants were sprayed at three concentrations: 500, 1000 or 1500 ppm of chlormequat and 37.5, 50.0 or 62.5 ppm of ancymidol. Spraying was performed once, twice or three times. Plants not receiving any growth retardants were used as controls. The time taken to reach anthesis and the sale stage differed significantly between treated and untreated plants only in the begonias sprayed twice with 1000 ppm chlormequat, which reached anthesis one week later than the controls. Both of the growth regulators reduced the growth in height, and ancymidol also reduced the growth in width. The flower stalks were significantly shorter in plants treated with ancymidol or two or three times with chlormequat than in the controls. No differences were observed in the number of branches, flowers or flower buds, or in the diameter of the root collar. The greatest proportions of saleable plants were obtained by spraying once with 500 or 1000 ppm chlormequat or leaving the plants untreated. The concentrations of ancymidol were too high, since the plants treated with this growth regulator were extremely compact and unsaleable.