The effect of storage temperature on biochemical changes in autumn daffodil bulbs (Sternbergia lutea (L.) Ker Gawl. ex Spreng.) and its impact on interactions with photoperiod and morphological indices

Understanding bulb dormancy while examining temperature-related requirements and photoperiod are essential for successful commercialization and the greenhouse forcing of autumn daffodil (Sternbergia lutea). In this study, autumn daffodil bulbs were stored at 5, 15 and 25 degrees C for one month. Then, one group of bulbs were evaluated in terms of biochemical characteristics in three parts of each bulb (scale, central bud and basal plate). A second group of bulbs were planted in a greenhouse for a separate experiment to study the effects of different photoperiods (short, moderate and long) on morphological traits. The heat map of treatments in the first experiment revealed that the bulb storage temperatures of 15 degrees C and 25 degrees C had somewhat similar effects on all three parts of the bulb but, conversely, 5 degrees C had discrete effects. The 5 degrees C resulted in higher contents of proline in the scale, along with more H2O2 and malondialdehyde (MDA) in the basal plate. The highest activity of peroxidase (POD) and superoxide dismutase (SOD) were observed at 15 degrees C in the basal plate and at 5 degrees C in the central bud, respectively. In the second experiment, the time required for bulb sprouting and time to flowering were as follows: 5 degrees C>25 degrees C>15 degrees C. The heat map analysis indicated that temperature played a more substantial role than what photoperiod did in shaping the morphological traits. The interaction between 15 degrees C and the moderate photoperiod led to the highest value of most vegetative traits and of flowering percentage (70%). Therefore, this treatment can be considered as optimum for breaking relative bulb dormancy and to succeed better in growth and flowering.

Automated summary

Understanding bulb dormancy and the impact of temperature and photoperiod on autumn daffodil is crucial for commercial success and greenhouse forcing. Storage temperature had varying effects on different parts of the bulb, with 15 degrees C showing similar effects on all parts while 5 degrees C had distinct effects. Temperature played a more significant role than photoperiod in shaping morphological traits, with the interaction of 15 degrees C and moderate photoperiod resulting in the highest value of vegetative traits and flowering percentage.