Postharvest illumination of alstroemeria: Effect of light quality on flower metabolism and shelf life

Despite the good postharvest performance of alstroemeria flowers, leaf yellowing is one of the most important signs of senescence and decay, as well as the flower size and time to abscission. In this work, we tested the effect of 50 mu mol m(-2) s(-1) white (WL, broad spectrum) and red-blue (RBL, 40:60, 630 + 465 nm) light-emitting diodes on cut alstroemeria stored at 20 degrees C, or WL on cut alstroemeria stored at 5 degrees C, on postharvest flower quality and vase life. The light-treated floral stems had higher water consumption throughout storage compared to the controls stored in the dark, with no variation in stem diameter. The tepal area was increased by the light treatment at both storage temperatures. The leaf color remained similar to that at harvest in the light-treated flower stems (WL and RBL), while there was a strong yellowing in the controls stored in the dark. Anthocya-nins increased mostly in flowers stored under WL, although this was more evident at 20 degrees C. WL treatment strongly slowed chlorophyll degradation and increased sugar content in leaves and tepals by 3.4 and 1.8 times, respectively, at 20 degrees C, and by 6 and 2.9 times, respectively, at 5 degrees C. The increase in sugar levels in light-treated flowers may have caused the tepal expansion but also delayed the onset of leaf senescence, and consequently the tepal abscission. The WL was the most effective storage condition not only to extend cut alstroemeria shelf life, but also to improve the postharvest flower quality, both at room temperature and under refrigeration.