Significance of light climate in the culture and management of ornamental plants

Abstract

The growth of Sinningia speciosa plants grown under various light intensities (60, 54, 30, 16, 10, and 5%-daylight) was pursued from March 21 to June 17, 1967.1. The growth in dry weight of total plant, leaf and tuber were markedly depressed under deep shade (10 and 5%-daylight).2. The light intensity of 16%-daylight was optimal for the growth in leaf area of main stem. The growth of lateral branches was depressed under deeper shade (16, 10 and 5%-daylight).3. The ratio of leaf area to leaf weight (L/F ratio) and of leaf length to width (1/b ratio) significantly increased with the decrease of light intensity. Leaves of plants grown under lower light intensities were green in color, while those exposed to higher light were yellowish.4. Flowering was earlier at higher light condition than at the lower. The size, shape and color of flower were not influenced with shading.5. Light saturation and compensation points for the apparent photosynthesis were about 10 kilolux and 100-300lux, respectively. The maximal photosynthesis was 4-6.5mg CO2/dm2/hr. It was somewhat lower in 60 and 5%-daylight leaves as compared with in the middle shaded.