Infradian rhythms of increment dynamics of shoots in clones of almond willow (Salix triandra, Salicaceae)

Abstract

Abstract. Purpose of research – harmonic analysis of the structure of seasonal dynamics of daily increment of shoots in almond willow (Salix triandra) clones. Research methodology and methods. Object is a model population created by cuttings of sibs-seedlings from the same family obtained by regular inbreeding over three generations. Material – growing long shoots. Experimental group: seven clones of one-year saplings from cuttings; 6-fold repetition. Control group – seedlings from the same family on their own roots of the fourth year of life. Methods: comparative morphological, chronobiological, numerical analysis of time series. Observations were made during the growing season of 2020. Results. The beginning of the growth of shoots – the end of the first decade of May. The maximum daily increase is in early summer (06.06…14.06). Further, the daily growth decreased unevenly until the end of August. Seasonal dynamics of daily increment is determined by the interaction of linear and nonlinear components. Linear components determine the seasonal trend of daily increment dynamics. They are approximated by the corresponding regression equations with different reliability. Nonlinear components determine the cyclical nature of the seasonal dynamics of daily increment. They are approximated by sums of harmonics with an oscillation period of 9–144 days with very high reliability. Scientific novelty. The cyclical nature of the seasonal dynamics of daily increment is determined by the interaction of biorhythms with different periods. Subannual biorhythms with a period of more than 48 days correct seasonal trends of daily increment. Infradian biorhythms with a period of 9...36 days determine the alternation of peaks and dips in the seasonal dynamics of daily increment. Biorhythms with a period of 29...36 days were synchronized in the experimental and control groups, but shifted in phase when comparing the experiment and control. Biorhythms with a period of 21...24 days are synchronized on all the researched shoots. Biorhythms with a period of 9…18 days are not synchronized, but their resulting fluctuations affect the dynamics of daily increment at the beginning and end of the growing season.