Use of chlorophyll a fluorescence for evaluating senescence in leafy vegetables

The aim of this work is to evaluate leaf senescence rate via chlorophyll a fluorescence measurements and with the JIP test. Lettuce (Lactuca sativa L.) and spinach (Spinacia oleracea L.) vegetables were stored at 4 or 8 °C. The performance index (PIABS) was the only index that immediately changed, even after one day of storage. The cumulative respiration was higher at higher storage temperature (8 °C). At the end of storage, the cumulative respiration was 318 and 398 mg CO2/100 g FW for lettuce and spinach, respectively. The data from the induction curves were correlated with cumulated respiration. A multivariate regression model showed a satisfactory predictive ability with a R2 in validation of 0.67 and a standard error in prediction (RMSEP) of 170 mg CO2/ 100 g FW corresponding to the CO2 emission of 3.5 days at 4 °C and of 2.1 days at 8 °C.