Macronutrients play important roles in plants and control many of their physiological and biochemical processes. Moreover, they are required for livestock and human health. So, this experiment was conducted in 2010 in the Veterinary Science Research Institute, Karaj, Iran, to evaluate the effect of planting time on the nutrient uptake of two amaranth varieties. The experiment was conducted in split plot in the form of a randomized complete block design with four replications and two factors: planting time as the main factor (spring and summer) and variety as the sub factor (Amaranthus hypochondriacus L. var. Cim and var. Kharkofski). Results indicated that planting time, variety and their interactions significantly affected all the measured traits, except for the effect of the interaction which was not significant on P content. Mean comparison indicated that N content was the highest (2.83%) in the interaction of spring × Cim. K and Mg contents were the highest (0.78 and 0.69%, respectively) in spring × Kharkofski. Finally, P and Ca contents were the highest (0.76 and 0.97%, respectively) in summer × Kharkofski.
