OXALATE CONCENTRATION IN SPINACH LEAVES DURING ONTOGENESIS
Changes in oxalate concentrations in individual leaves during ontogenesis were examined by a sequential sampling of spinach plants grown in solution culture. The period between initiation of two successive leaves was 1.58 days. Fresh weight of each leaf increased at a constant rate with time after the leaf became 1 cm in length. Oxalate concentrations in plant tops decreased gradually with plant age. Oxalate concentrations in each leaf remained constant during ontogenesis, and they were negatively correlated with the leaf position numbered from the base. Leaf growth rates and the relationship between oxalate concentrations and leaf position were combined to make a model that describes the changes in oxalate concentrations in plant tops as the age of the plant advanced. The resulting model indicated that oxalate concentrations in plant tops decreased more rapidly as plastochron became shorter.