Effects of desiccation on the 77°K fluorescence properties of the liverwort Porella navicularis and the isolated lichen green alga Trebouxia pyriformis |
| |
Authors: | Gunnar Öquist David C Fork |
| |
Institution: | Department of Plant Physiology, Attila József University, P.O. Box 428, Szeged, Hungary, H-6701 and E. Haunold, Institute of Agriculture, Austrian Research Center, A-2444 Seibersdorf, Austria. |
| |
Abstract: | The uptake of the auxin type herbicide 2,4-D into rice seedlings ( Oryza sativa L. cv. Dunghan Shali) and its effects on the K+, NH+4 and NO3 ion uptake and the K+ content were investigated at different pH values. A short incubation of the roots in 0.01 m M 2,4-D caused a marked ion uptake inhibition only at low pH. The non-auxin type herbicide benthiocarb did not produce such an inhibitory effect. Lowering of the pH in the external medium led to an increased 2,4-D uptake by the roots. These results can be explained by the increased H+ permeability of the membranes, allowing a more rapid entrance of 2,4-D into the root cells, thereby inhibiting the active ion uptake. Rice roots not subjected to 2,4-D treatment responded to H+ stress with an increased anomalous K+ uptake and a decreased K+ content. With reference to the effects of pH changes on the ion and 2,4-D uptake, possible transport mechanism of NH+4 and 2,4-D are briefly discussed. |
| |
Keywords: | K+ NH+4 NO3 herbicide benthiocarb H+ stress uptake anomaly K+ content low-salt condition cell membrane growth translocation |
|
|