EFFECT OF ACCUMULATED MINIMUM TEMPERATURE ON SUGAR AND ORGANIC ACID CONTENT IN PASSION FRUIT

To determine the suitable harvest timing of passion fruit, the effect of accumulated minimum temperature (AT min ) on the content of sugar and organic acid of passion fruit was studied. We used AT min instead of fruit development period (FDP) as a scale to determine the relationship with fruit quality, because FDP was found to be influenced strongly by the average of daily minimum temperature (r = -0.788**), and also because the quality parameters were found to be associated more significantly with AT min than with FDP. Fructose and glucose started to increase, and citric acid began to decrease when AT min reached 1000 o C day. The fruit reached acceptable quality as 15.0 and 2.9 g/100mL for the total sugar and organic acid content, respectively, when AT min reached 1350 o C day, and it was found that the fruit with more AT min had a higher quality. On the other hand, the fruit drop occurred frequently when AT min was less than 1350 o C day, indicating premature drop. We suggest that AT min can be a suitable parameter to discuss passion fruit quality which might well contribute to check the best harvest timing of passion fruit cultivating countries in Southeast Asia.