Yutaka Shinohara

Effects of Night Temperature on Gas Exchange Characteristics in Different Tomato Ecotypes

Abstract To clarify the effects of night temperature on gas exchange characteristics in tomatoes, 3 cultivars (Japanese, ‘Ogata Zuiko’; North European, ‘Money Maker’; South European, ‘Roma’) were treated at the early flowering stage in artificially illuminated growth cabinets for 3 weeks at 30 15 and 30 30° C , day/night temperatures. Gas exchanges were measured in relation to leaf temperature and irradiance. The optimum temperature and light saturation point for net photosynthesis was about at 30°C and 900 μmol m −2 s −1 PPFD, respectively. They were little affected by the night temperature. ‘Money Maker’ was the most efficient at 30°C, ‘Ogata Zuiko’ was the least sensitive to temperature change, and ‘Roma’ was the least efficient and the most sensitive to high temperatures, especially when grown at 30°C-night. Transpiration in all 3 cultivars was correlated with net photosynthesis. ‘Roma’ showed a lower ratio of photosynthesis to respiration when grown at 30°C-night than the other 2 cultivars. Photosynthesis of ‘Ogata Zuiko’ and ‘Money Maker’ was tolerant, and that of ‘Roma’ was sensitive, to high night temperature.

Effects of bulb desiccation and storage on the in vitro propagation of hyacinth

Abstract The effect of long-storage and silica gel desiccation of hyacinth bulbs (Hyacinthus orientalis L.) on in vitro bulblet formation was investigated. Bulbs of 3 cultivars were stored at 25°C and 50–60% relative humidity for 17 months. This long-term storage of bulbs markedly enhanced bulblet initiation from scales and growth of regenerated bulblets. Bulbs of 5 cultivars were desiccated with silica gel for 5 and 20 h before in vitro propagation. The total number of bulblets increased as a result of 5 h desiccation with silica gel. Bulb desiccation for 20 h caused a large increase in the growth rate of bulblets. This desiccation treatment with silica gel is a practical method to obtain many and more regenerative explants in the in vitro propagation of hyacinth.