Influence of chemical characteristics of soil on mineral and alkaloid seed contents of Colchicum autumnale

Alkaloids from meadow saffron seeds are used in numerous medicines. Variations of seed alkaloid content (colchicine and colchicoside) were observed between natural sites. Nevertheless, this character remained stable when these accessions (corms collected on different natural sites) were cultivated in a same field. A relation between soil properties and seeds alkaloid content can be expected. Soil analyses were performed in three soil layers (0-30, 30-60, 60-90 cm) on three meadow saffron natural sites and two cultivated sites. Linear regressions were performed between 20 soil factors, analysed in the three soil layers and the seed alkaloid content. Cobalt and calcium soil contents were positively correlated with seed alkaloid content. The coefficients of determination (R2) were the highest in the 30-60 cm soil layer, respectively, of 0.85 and 0.74. Mineral analyses were performed on seed. In spite of the important difference of level, linear relations were observed between the sum of Ca and 1000 × Co contents (Ca + Co) in seeds and in soil (R2 = 0.76). A highly significant relation was shown between (Ca + Co) in seeds and alkaloid content (R2 = 0.96) showing for the first time on Colchicum autumnale the positive influence of these mineral elements on the alkaloid synthesis. Soil and foliar supplies of Ca and Co could be tested to improve seed alkaloid content.