ISHS Acta Horticulturae 394: Plant Bioregulators in Horticulture
EFFECT OF SUPRAOPTIMAL ROOT TEMPERATURE ON ABA LEVELS IN CUCUMBER PLANTS AND ITS CONTROL BY ABA APPLIED TO ROOTS |
| Authors: | Y.C. Du, S. Tachibana |
| Keywords: | Abscisic acid, Cucumis sativus, High root temperature |
| Abstract:
Cucumber seedlings (Cucumis sativus L. cv. Sharp I) were grown in water culture at root temperatures ranging from 25°C to 38°C for up to 10 days. Roots grown at 35°C and 38°C had 50% lower endogenous ABA levels than those at 25°C and 32°C at day 5. However, at day 10 ABA levels in roots at 38°C showed an 8-fold increase over those at 25°C root temperature. No such increase occurred in roots at 32°C and 35°C. ABA levels in leaves did not differ with root temperatures at day 5, but they increased dramatically at day 10 in plants grown at 35°C and 38°C. Exogenous ABA applied to roots at 10-7M or 3X10-7M at the start of temperature treatment prevented the high root temperature-induced changes of ABA levels in both roots and leaves. Growth inhibition at 38°C was partially alleviated. ABA treatment caused a significant increase in water and ion flux to the xylem exudate in roots at 38°C, but showed a little effect in roots at 25°C. | |
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