Osmotic adjustment and the inhibition of leaf, root, stem and silk growth at low water potentials in maize
✍ Scribed by M. E. Westgate; J. S. Boyer
- Publisher
- Springer-Verlag
- Year
- 1985
- Tongue
- English
- Weight
- 979 KB
- Volume
- 164
- Category
- Article
- ISSN
- 0032-0935
No coin nor oath required. For personal study only.
✦ Synopsis
The expansion growth of plant organs is inhibited at low water potentials (~w), but the inhibition has not been compared in different organs of the same plant. Therefore, we determined elongation rates of the roots, stems, leaves, and styles (silks) of maize (Zea mays L.) as soil water was depleted. The 7tw was measured in the region of cell expansion of each organ. The complicating effects of transpiration were avoided by making measurements at the end of the dark period when the air had been saturated with water vapor for 10 h and transpiration was less than 1% of the rate in the light. Growth was inhibited as the 7tw in the region of cell expansion decreased in each organ. The ~w required to stop growth was -0.50, -0.75, and -1.00 MPa, in this order, in the stem, silks, and leaves. However, the roots grew at these 7Jw and ceased only when ~w was lower than -1.4 MPa. The osmotic potential decreased in each region of cell expansion and, in leaves, roots and stems, the decrease was sufficient to maintain turgor fully. In the silks, the decrease was less and turgor fell. In the mature tissue, the ~w of the stem, leaves and roots was similar to that of the soil when adequate water was supplied. This indicated that an equilibrium existed between these tissues, the vascular system, and the soil. At the same time, the ~w was lower in the expanding regions than in the mature tissues, indicating that there was a ~Pw disequilibrium between the growing tissue and the vascular system. The disequilibrium was interpreted as a ~w gradient for supplying