ISHS Acta Horticulturae 792: V International Symposium on Irrigation of Horticultural Crops
DEVELOPMENT OF A METHOD FOR DETECTING THE ONSET OF DROUGHT STRESS IN ASPARAGUS FERN |
| Authors: | J. Schaller, P.-J. Paschold |
| Keywords: | Asparagus officinalis L., water deficiency, hydraulic conductivity, xylem water potential, air blockages |
| Abstract:
To explore the impact of water deficiency on the water transport in asparagus fern, it is required to investigate the hydraulic conductivity (ch) of shoots combined with the xylem water potential (  x) of shoots.
The motivation for this study was to design a novel ch-measuring system adapted for the herbaceous monocot asparagus.
The method described by Sperry et al. (1988) - developed to investigate drought stress of woody species - was therefore modified.
Within this study, the ch was calculated as water flow rate (WFR) per pressure gradient.
The drought-induced loss of ch is described as the quotient of the maximum and actual (= limited) ch in shoots.
When relating this measure to the appropriated plant water status (x), the initial limitation of ch can be explored.
For the adapted method, asparagus branches of 2nd order were detached and inserted into the measuring system under water to avoid artificial air penetration into xylem conduits.
As perfusing solution, distilled and degassed water was used in order to prevent outgassing during the measurement.
The height of the gravimetrically induced hydrostatic pressure gradient was adjusted to the water conduits of asparagus.
In order to elute air blockages out of xylem vessels, the branch segments were flushed with defined high pressure for a certain period of time.
Subsequently determined maximum ch showed constant flow rates indicating complete elimination of air embolism.
With this technique, the onset of drought stress in asparagus branches is ascertainable.
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