Effect of Harvesting and Drying Conditions on Chlorophyll Levels of Soybean (Glycine max L. Merr)
2003
Gomes, M. Salete O. | Sinnecker, Patricia | Tanaka, Roberto T. | Lanfer-Marquez, Ursula M.
Chlorophyll in soybean represents a downgrading factor for the crops. Five Brazilian cultivars were harvested between R6 and R8 stage of development (Fehr & Caviness scale) and dried at 25° and 40 °C. The effect of maturity stages and two drying conditions after harvest were studied to achieve reduction of moisture and chlorophylls to acceptable levels. When seeds were dried at 25 °C, even harvesting at early stages of development such as R6, the green pigments were almost degraded, and 16 ppm of chlorophyll were found at maximum, accompanied by loss of moisture. Moisture and chlorophyll declines as seed matures, but at intermediary stages (R6−R7), chlorophyll degrades first, so the rate of moisture loss should not be used to predict chlorophyll contents. At 40 °C, complete degradation of chlorophyll pigments is only achieved when seeds are swathed from R7 stage up, otherwise the seed quality could be compromised. Slow drying allows almost complete removal of green pigments, even when seeds are swathed a few days before the physiological maturity stage.
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