Root topology and allocation patterns of Atriplex patula supplied with different nutrient concentrations

Abstract

To test whether sub-optimal available nutrient concentrations would result in a more herringbone root branching pattern, in lower root diameters, and in greater resource allocation to root growth than to above-ground portions, seedlings of Atriplex patula were grown under optimal (full), intermediate (1/3 full), and low (1/6 full) nutrient treatments. No significant differences were found between the full and 1/3 nutrient treatments for any of the parameters tested. Root topologies did not show conclusive responses to nutrient availability, however roots treated with 1/6 nutrient concentration showed the tendency to grow in a more herringbone pattern. Total dry weights and shoot dry weights were lower for the plants grown with 1/6 nutrient solution than for the other treatments. Root dry weight, length, and diameter were similar in all treatments. Root/shoot ratios of the 1/6 nutrient treatment were significantly higher than those of the other treatments. Results sug- gested a nutrient level threshold for Atriplex patula located between the intermediate and low nutrient levels provided. The sizes and forms of the roots were fairly conservative among treatments, indicating an allocation strategy towards obtaining their limiting resources.