Effects of Monochromatic Radiations on Growth of Pelargonium Callus Tissue

Abstract

Pith callus tissues were grown under continuous blue (450 mμ), green (545 mμ), red (650 mμ), and ‘white’ (full-spectrum) light, and in the dark for 22 days at 27±2° C at energy levels of 15,000 ergs cm⁻² sec⁻¹. Mean increases in fresh weight of tissues grown under ‘white’ and blue light were significantly greater than those of tissues grown in green and red light and in the dark. Tissues grown in the dark yielded mean fresh weight increases significantly lower than tissues grown under blue, red, and ‘white’ light. No significant differences were shown between blue and ‘white’, red and green, and green and dark treatments respectively. Cell differentiation occurred in all treatments only to the extent of vessel element formation. There were no differences in degree of differentiation between treatments. It was proposed that the high-energy reaction of photomorphogenesis was in operation in the Pelargonium callus tissue. The results indicated the presence in the tissue of high-energy photoreceptor(s). The use of high-intensity, incandescent illumination for experimental procedures approximating natural conditions of irradiation was indicated as desirable for pith callus tissues of Pelargonium zonale var. Enchantress Fiat.