The Technique of Water Extract Preparation from Goat Willow Leaves with Allowance for Circadian Rhythm of Their Biological Activity to Stimulate Scots Pine Seed Germination

Abstract

The preparative technique for water extraction of goat willow (Salix caprea L.) growing leaves was elaborated in order to stimulate Scots pine (Pinus sylvestris L.) seed germination by the extracts (patent no. 2662999). It was shown that the effects of the extract were accounted for by its biological activity, which considerably varied depending on the time of day for extract sampling. The maximal increase in gibberellin-like activity (equivalent to 3.4–3.6 µM GA₃) and marked decrease in ABA-like activity (equivalent to 0.15‒0.30 µM ABA) were recorded in the willow leaf extracts harvested in the morning (8:00 a.m.) or evening (8:00 p.m.) in South Karelia (60° N) in mid-May. Application of the extracts to pine seeds afforded the maximal effects on their germination. Thus, the second-class seeds displayed qualitative characteristics of the first-class seeds (germination exceeding 80%) after the treatment. It is concluded that the introduction of the method into practice will allow utilization of the accessible, widespread plant raw material for production of the effective natural preparation, which is capable of improving sowing qualities of Scots pine seeds.