Study of the water potential dynamics in Betula pendula Roth trees using cosinor- analysis

On the basis of measured data on Ψ diurnal and seasonal variations, the additive model of water potential (Ψ) seasonal dynamics in silver birch (Betula pendula Roth) and curly (Karelian) birch (Betula pendula Roth var. carelica) was developed using cosinor- analysis. The analysis of Ψ time series revealed that diurnal Ψ biorhythms in silver birch and curly birch shoots changed unidirectionally over the growing season although the scope of variability differed significantly. More substantial changes of the studied parameter during the growing season were noted in curly birch. It was shown that the modeling of biorhythms of water status parameters enables to understand better the processes of water regime regulation in plants, as it allows detecting specific intra-species differences, which are difficult to determine using conventional methods of statistical data treatment