Stem radius variations result from the fluctuation of environmental factors, mostly temperature trend and water availability, in turn affecting plant water balance, and plant growth. High-resolution analysis ofstem radius variation provides insights into the temporal patterns in radial growth and water balance, andtheir relationship with environmental variables. To test the causal effects of temporal climate fluctuationon stem radius variation, a mathematical procedure was applied to normalize and synchronize radialfluctuations and environmental parameters, whose baseline is largely unexplored.Stem radius variations were continuously monitored during two consecutive years in four saplingsfield-grown olive tree cultivars (Canino, Cipressino, Leccino, Maurino) in an experimental farm in centralItaly, between November 2004 and October 2006, using automatic high-resolution point dendrometers.A derivative analysis approach applied on point dendrometer records was conveniently used to describestem radius variation and to distinguish the timing of transition from the dormant winter state to theactive growth stage and till the slow expansion phase.Stem diameter patterns showed intense shrinkage events suddenly after air temperature drop below0 ◦C during winter. The onset of radial growth was delimited by the occurrence of rehydration (beginningof transpiration cycles) and increase of air temperature (end of cold cycles). The course of the growingseason was described by patterns of air temperature, reference evapotranspiration, cumulative degreedays,vapour pressure deficit and soil moisture deficit, and correlated to patterns in stem radius cycles.Three phases of stem radius variation were evidenced through the seasonal course: induction signal,growth period, and slow expansion.This approach provides new and objective insights on shrinkage–swelling phenomena in Mediterraneanenvironments, related to dehydration and hydration cycles, which are difficult to detect withempirical treatment of stem radius variation records. The ability to switch quickly between dormancy togrowth would enable the olive tree to restart physiological processes and to cope with erratic climatic conditions of the Mediterranean region.
|Titolo:||A novel mathematical procedure to interpret the stem radius variation in olive trees|
|Data di pubblicazione:||2012|
|Appare nelle tipologie:||1.1 Articolo in rivista|