The Effect of Post-harvest Conditions in Narcissus sp. Cut Flowers Scent Profile

Narcissus flowers are used as cut flowers and to obtain high quality essential oils for the perfume industry. As a winter crop in the Mediterranean area, it flowers at temperatures ranging between 10 and 15 degrees C during the day and 3-10 degrees C during the night. Here we tested the impact of different light and temperature conditions on scent quality during post-harvest. These two types of thermoperiod and photoperiod. We also used constant darkness and constant temperatures. We found that under conditions of 12:12 Light Dark and 15-5 degrees C, Narcissus emitted monoterpenes and phenylpropanoids. Increasing the temperature to 20 degrees-10 degrees C in a 12:12 LD cycle caused the loss of cinnamyl acetate and emission of indole. Under constant dark, there was a loss of scent complexity. Constant temperatures of 20 degrees C caused a decrease of scent complexity that was more dramatic at 5 degrees C, when the total number of compounds emitted decreased from thirteen to six. Distance analysis confirmed that 20 degrees C constant temperature causes the most divergent scent profile. We found a set of four volatiles, benzyl acetate, eucalyptol, linalool, and ocimene that display a robust production under differing environmental conditions, while others were consistently dependent on light or thermoperiod. Scent emission changed significantly during the day and between different light and temperature treatments. Under a light:dark cycle and 15-5 degrees C the maximum was detected during the light phase but this peak shifted toward night under 20-10 degrees C. Moreover, under constant darkness the peak occurred at midnight and under constant temperature, at the end of night. Using Machine Learning we found that indole was the volatile with a highest ranking of discrimination followed by D-limonene. Our results indicate that light and temperature regimes play a critical role in scent quality. The richest scent profile is obtained by keeping flowers at 15 degrees-5 degrees C thermoperiod and a 12:12 Light Dark photoperiod.