Title : Preferential allocation of currently assimilated carbon in young cork oaks (Quercus suber L.)
Abstract:
Understanding the allocation of currently assimilated carbon by leaves in young cork oaks (Quercus suber L.) is crucial to determine the main physiological factors limiting growth in field conditions, under a changing climate. In this study, for the first time, allocation patterns of recently assimilated carbon by leaves in branches at different positions on the shoots of six-year-old cork oaks were assessed through 14CO2 pulse-labeling in late spring (end-May). Our results showed that source leaves retained most of its own current produced carbohydrates, with top branches source leaves retaining the highest amount (64.4%) as compared to either lower (49.4%) or middle (41.7 %) branches source leaves. The greatest percentage of the available current carbohydrates exported from source leaves was found in the root system, ranging between 17.2% and 36.7%. These findings support our conclusion that in young cork oaks, the root system displayed the greatest sink strength for the available current carbohydrates in late spring within the growing season due to its large biomass, and mainly when other strong sinks such as developing leaves are no longer competitive. Under Mediterranean environments in a changing climate, these results are mostly needed for better understanding cork oak survival and growth and for adequate forest management practices towards cork oak woodlands conservation.
Keywords: Mediterranean evergreen oak, cork oak, 14C-photoassimilates, whole-plant carbon source-sink relationships
This is an innovative study on the investment of available current carbohydrates produced by branches leaves in three different positions on shoots, to plant growth and maintenance in late spring. This research emphasizes the importance of leaves in lower positions for the development of the deep root system of Q. suber which allow the trees to access deep water resources to overcome hot and dry summers in Mediterranean climate. This study would be of interest to the researchers and academics working on carbon economy of woody plants, in particular, the Mediterranean species.
