Selection of Suitable Methods for Sample Preparation and Desorbing Agents for Determination of Nutrient Contents in Scots Pine Roots

Abstract

Determining the nutrient composition of woody plant roots is an important tool for studying the physiological response of trees to various environmental factors. Considering the complexity and labor intensity of collecting the roots of woody plants, especially coniferous plants, it is of particular importance to use a suitable method for the desorption of excess nutrients from the root surface to avoid the overestimation of nutrient content within the roots. In the present study, various methods for sample preparation of the roots of both Scots pine (Pinus sylvestris L.) seedlings grown in hydroculture with different aeration regimes and saplings grown in soil substrates were investigated to determine the contents of magnesium, potassium, calcium, phosphorus, iron, manganese, zinc and copper. The possibility of using root samples frozen in liquid nitrogen was also investigated. The effectiveness of different desorbing agents such as Na₂-EDTA, dithionite-citrate-bicarbonate, CaCl₂ and MES-Tris for nutrient removal from the root surface, as well as the duration of incubation, were studied. It was shown that desorption of nutrients from roots using EDTA is the preferred method when working with soil-grown roots. In the absence of iron-manganese plaques on the root surface, treatment of roots with DCB should not exceed 5-10 minutes to avoid ion leakage from root cells. If it is not possible to use any extraction methods, it is sufficient to mechanically remove the remaining soil particles from roots, rinse the roots with water and dry. However, this sample preparation method is not suitable for determining the iron content in roots.