Interaction effect of potassium and drought stress on potassium uptake and transport in two canola (Brassica napus L.) cultivars

Salehi Eskandari, B., B. Kholdebarin and A. Morad Shahi. 2010. Interaction effect of potassium and drought stress on potassium ion uptake and transport in two canola (Brassica napus L.) cultivars. Iranian Journal of Crop Sciences. 13 (1) 49-60. (In Persian)Drought stress is an ever-increasing problem that severely limits crop production worldwide particularly in arid and semi-arid areas. The effect of water stress simulated by polyethylene glycol-6000 (PEG 6000) on K+ uptake and transport responses in two canola cultivars was studied. Based on their plumule and radicle dry weight, AG and PO4 cultivars were selected as the high and the low drought tolerant, respectively. The effect of drought stress (0, -0.29, -0.48 and -0.71 MPa) on K+ uptake and transport in these two cultivars grown in nutrient solutions containing 5 mM KCl was studied. In a second experiment, the rate of K+ uptake from different concentrations of KCl at a fixed water potential (-0.48 MPa) was also studied. Both of experiments were carried out in comletely randomized design in factorial layout with three replications. K+ uptake was determined by flame photometry. Water stress reduced the rates of K+ uptake by the two cultivars. However, the observed reduction was more pronounced in drought stress sensitive cultivar. The rate of K+ uptake by the two cultivars increased by the increase in K+ concentration. Increase in K+ uptake was more pronounced in tolerant cultivar. In the absent of K+, water stress caused K+ endogenous leakage which was greater in sensitive cultivar indicating cell membrane damage by water stress. Results showed that under water stress K+ uptake by canola cultivars was different and K+ alleviated some deleterious effects of drought stress.