Abstract
Ascorbic acid content is an important factor in spinach (Spinacia oleracea L.) quality. In this study, we investigated the effects of the amount of solar radiation and temperature on the ascorbic acid content of spinach. Experiments were carried out under rain shelters on four sowing dates. Spinach plants were harvested when they reached marketable size, and ascorbic acid contents were measured. The ascorbic acid content of spinach on a fresh-weight basis increased or decreased within each day and also changed with similar tendency to the integrated amount of solar radiation on the day before harvesting. This result suggests that the ascorbic acid content on a fresh-weight basis is strongly affected by the total amount of solar radiation received by the plants one day before harvesting. Diurnal changes in the ascorbic acid content on a fresh-weight basis were largely affected by the ascorbic acid content on a dry-weight basis and partly affected by the water content of the plants.
