Effect of Growth Rates on Oxalate Concentrations in Spinach Leaves

Abstract

Relationships between growth rates and oxalate concentrations in spinach leaves were examined for 14 cultivars grown in solution culture in the spring and fall. Spinach leaves were harvested twice within a one-week-interval in both seasons; the incremental change in fresh weight of leaves and the relative growth rate (RGR) of leaves for the 7-day period were calculated.
The correlations between RGR for leaves and their oxalate concentrations at any harvest in both seasons were insignificant. An increase in fresh weight of leaves between the first and the second harvest was significantly correlated to oxalate concentration of leaves in both seasons. Oxalate concentration of leaves decreased from the first to the second harvest in most cultivars examined in this study; the decrease was significantly correlated to the increase in fresh weight of leaves.
The above results suggest that oxalate concentrations in leaves decreased more with time in cultivars with rapid growth rates than it did in those with slow growth rates.