Abstract

The rubber-producing species Scorzonera tau-saghyz (mountain gum) was used as a significant source of natural rubber between 1930 and 1950 by the U.S.S.R because this perennial species can accumulate up to 40% rubber in its roots on a dry weight basis. Wild stands were harvested, and plants were tested in nursery and field trials in multiple locations. Most of the data are lost but a few, rare, early reports have been discovered and translated by our co-authors in Kazakhstan. In this paper, these early data from different sites have been plotted and analyzed to guide modern cultivation efforts in both Kazakhstan and the United States. The use of an NPK complex fertilizer appeared most effective in increasing overall yield, promoting growth, and enhancing the content of rubber, resin, and carbohydrates in the plants. The highest rubber and the lowest resin concentrations were observed in September-October. The greatest yields of root biomass and rubber were obtained on relatively acidic, magnesium-rich soils (pH 5.35–7.45) with a mild climate (Krasnograd, Ukraine). However, S. tau-saghyz was able to perform quite well even when winter temperatures dropped to -20 °C (Poltavka, Russia). Good plant performance on the Poltavka, Krasnograd and irrigated Almaty (Kazakhstan) sites suggests that adequate water is needed for good yield. Lack of water and higher pH both appeared to be detrimental to yield in Balashov (Russia), and non-irrigated Almaty.