Seasonal Dynamics of Internodes Length of the Shoots of Salix dasyclados Wimm. (Salicaceae Mirb.) Against the Background of Early Summer Drought Stress

Abstract

The article substantiates the need to study the influence of hydrothermic conditions on the linear growth of shoots of woolly-stemmed willow. Purpose of research: identification and analysis structure of seasonal dynamics of internodes length of the shoots of S. dasyclados against the background of short atmospheric drought. Object of research: model inbred-clone population of S. dasyclados. Material: growing and matured annual shoots on two-year-old roots. Research methods: empirical methods of experimental botany, computer technologies of data analysis. Results. Against the background of the change of the early summer drought by cool rainy weather, the annual growth of the strongest shoots was 1.3 ... 2.5 m. The average length of internodes on the shoot varied from 23 to 31 mm. Seasonal dynamics of internode length can be approximated by linear trends in the first approximation. The deviations of the internode length from linear trends are nonlinear and are approximated by the equations of harmonic oscillations with a period of 96 ... 192 days. The strength of the influence of these harmonics on the seasonal dynamics of deviations of the internode length from linear trends is 2 ... 54%. The cyclicity of seasonal dynamics of deviations of internode length from linear trends is established. The revealed cyclicity is determined by the interaction of endogenous subannual and infradian biorhythms. Subannual biorhythms are approximated by harmonic oscillations with a period of 48 (64) days. The contribution of these biorhythms to the overall cyclicity is 23 ... 76%. Multi-day, or infradian biorhythms are approximated by harmonic oscillations with a period of 19 … 24 (32) days. The contribution of these biorhythms to the overall cyclicity is 3 ... 35%. High-frequency oscillations with a period of 12 ... 16 days are disordered. Differences between series of seasonal dynamics of internode length are determined by differences between shoots of a single ramet, between different ramets, and between different clones. The influence of from early summer drought stress on the seasonal dynamics of internode length has not been established.