Control of wheat root growth. The effects of excision on growth,wall rheology and root anatomy |
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Authors: | J Pritchard R G Wyn Jones A D Tomos |
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Institution: | (1) Department of Biochemistry and Soil Science, University College of North Wales, LL57 2UW Bangor, Gwynedd, UK |
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Abstract: | Excision and subsequent incubation of the apices (1 cm) of wheat (Triticum aestivum L.) seedling roots in simple media severely reduced elongation from 28 mm·(24 h)-1 in intact roots to a maximum of 2 mm·(24 h)-1 in excised roots. The reduction in growth was accompanied by a loss of cell turgor in the growing zone but was correlated with a hardening of the cell walls in this region. Rheological properties were measured as percent extensibility (both plastic and elastic) using a tensiometer, and as instantaneous volumetric elastic modulus (
i) using the pressure probe. Excision decreased plastic and elastic properties with a half-time of some 60 min. Plastic extension was reduced from 2.5% to 0.9% and elastic from 4.8% to 2.6% for an 8-g load. By contrast,
i was increased by excision. The observed reduction in root elongation rate was accompained by a reduction in mature cell length from 240 m to 40 m and a shortening of the zone of cell expansion.Symbol
i
instantaneous volumetric elastic modulus |
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Keywords: | Growth (root excision) Pressure probe Root growth (excision effects) Triticum (root growth) Turgor pressure Wall extensibility |
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