Seasonal Functional Partitioning of Carbohydrates and Proline among Plant Parts of the Sand Daffodil
Section of Botany, Department of Biology, National and Kapodistrian University of Athens, Athens 15784, Greece
Author to whom correspondence should be addressed.
Agronomy 2020, 10(4), 539; https://doi.org/10.3390/agronomy10040539
Received: 15 March 2020 / Revised: 3 April 2020 / Accepted: 6 April 2020 / Published: 9 April 2020
(This article belongs to the Special Issue Recent Advances in Research and Production of Ornamental Plants)
The sand daffodil (Pancratium maritimum) is a perennial geophyte, widely distributed and grown in a wild stage along the Mediterranean seashores. The aboveground tissues of this geophyte are exposed to harsh, ambient conditions and its large inflorescences of remarkable beauty and fragrance expand during the drought season and carry particular ornamental worth. The ecophysiological principles underlining metabolic processes of this geophyte are poorly understood. The seasonal variation of soluble sugars, starch, and proline was investigated in individuals collected from patches of P. maritimum, therefore, monthly measurements were performed in bulbs, leaves, scapes, and petals during a year. It was found that (a) sugar content showed similar seasonal trends between bulbs and leaves, as well as between petals and scapes, (b) bulbs contained enhanced starch concentrations irrespective of season, (c) proline accumulation exhibited substantial seasonal fluctuations among the considered tissues and pronounced differences were detected between maxima in petals and leaves. A substantial increase in both sugar and proline content was evident in petals during the drought season. In leaves, the accumulation of proline and, to a lesser extent, sugars was negatively correlated to the precipitation of the Mediterranean study site. It seems likely that the astonishing flowering of P. maritimum is supported by large leaf and bulb reserves.