Investigation of Vermicompost Influence on Seed Germination of the Endangered Wild Rubber Species Scorzonera tau-saghyz

In this paper, the effect of an organic fertilizer, namely, "vermicompost tea" (VCT), on the germination of seeds of the rare wild species Scorzonera tau-saghyz Lipsch. et & G.G. Bosse was studied. S. tau-saghyz is an alternative rubber plant to Hevea brasiliensis, and it was widely distributed and grew well in the northwestern spur of the Tien Shan in the pre-war years (1931-1943). In recent decades, the number of wild species of S. tau-saghyz in natural populations has declined sharply due to climate change and the impact of anthropogenic factors. In this context, it has become necessary to restore the number of wild species. One of the critical phases in the restoration of surviving S. tau-saghyz populations and domestication is seed germination. The approaches that have been explored to increase seed germination, such as stratification and seed dressing with ethyl mercuric chloride, have not yielded good results. The current study covered 4 and 8 h short-term seed treatments with 1, 5 and 10% VCT. The priming of S. tau-saghyz seeds with 10% VCT was found to significantly increase germination from 39.0 (in the control) to 76.7% and to improve seedling vigor, mean germination time, and seedling weight. The combination of soaking the seeds in 10% VCT for 8 h and cultivating the seedlings in soil with 20% vermicompost further improved both germination and seedling growth. The vermicompost incorporation lengthened the main root, which normally accumulates rubber, and it increased its crude biomass by 1.6 times compared to that of the control.