ISHS Acta Horticulturae 588: II International Symposium on Cucurbits
TRANSPIRATION AND XYLEM EXUDATES OF WATERMELON (CITRULLUS LANATUS THUNB.) UNDER CHILLING TEMPERATURES |
| Authors: | S.W. Kwon, D. Chil Choi, Y. Geun Choi |
| Abstract:
Watermelon plant (Citrullus lanatus Thunb.) responses to chilling temperatures were measured in terms of plant transpiration, chlorophyll fluorescence, and root xylem exudation. Water loss through transpiration increased with rising ambient temperatures. Plant transpiration was superimposed on diurnal rhythms in 7 h intervals during chilling at 6 °C and 14 °C. After chilling at 6 °C, Fv/Fm began to decrease slowly, and reached 72.3% in 3 days, while Fv/Fm changed little in plants grown at 14 °C or 30 °C. Root xylem exudation was more sensitive to low temperature than was plant transpiration. Such disproportionate responses between transpiration and xylem exudates can occur, due to decreased leaf turgor pressure, resulting in up-curling of leaves. Transfer of plants from 30 °C to 14 °C had a greater effect on xylem sap concentrations, such as inorganic phosphate, glucose, proline, and proteins, than any other parameter. The low temperature treatment also caused an increase in xylem sap pH by 0.1 to 0.8 units after 24 h to 72 h exposure. Chilling stress gave rise to inorganic phosphate, carbohydrate, proline, and protein flux, resulting in induced chilling tolerance. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
