Genetic variation in the uptake and utilization of potassium in wheat (Triticum aestivum L.) varieties grown under potassium stress

Summary

Three-week-old plants of twenty four wheat varieties were evaluated for potassium uptake and utilization under conditions of potassium stress. Both short-term and average net fluxes over a 16-day period were determined. Utilization was expressed as shoot fresh weight, efficiency ratio (g mmol ¹) and utilization efficiency (g² mmol⁻¹). To compare varieties developed during different periods in the history of wheat breeding, the varieties were assigned to five groups on the basis of height and origin, viz, tall Indian and Mexican types, semidwarfs, double dwarfs and triple dwarfs. Significant differences in short-term net flux, root and shoot weights, efficiency ratio and utilization efficiency were observed. Differences in average net fluxes were also considerable but unrelated to short-term net fluxes. Although short-term net fluxes were negatively correlated with root potassium concentration, some of the differences were not related to root potassium concentration thus indicating that they are genetically determined. Both short-term and averaged net fluxes were not correlated with root weight. Variability for efficiency ratio was slight but much more evident for shoot weight and utilization efficiency. Despite substantial variation within groups, considerable differences between groups were observed. The tall varieties, particularly those of Indian origin, and the triple dwarfs, were superior to the semidwarfs and double dwarfs for both short-term net fluxes and efficiency ratio. The tall Indian varieties exhibited the highest shoot weight and utilization efficiency. The poorest performers for both uptake and utilization were the double dwarfs. Intermediate in performance between the double dwarfs and the tall Indian varietes were the semidwarfs.