Saffron stigmas production as affected by soil texture

Saffron is considered a species that prefers sandy soils, but in many environments it is cultivated on silt soil or on drained clay soil. To evaluate the effect of soil texture on saffron production, corms of a Sardinian population (Italy) were sowed in the same piece of land on three different soil textures obtained mixing an increasing quantity of sand to a silt-clay soil: sand, intermediate and clay. Two corms densities (55 and 33 corms/m2) in plots four times replicated were also applied. Flower calendar, daily flower number and total stigmas weight were determined. Soil temperature was also measured. The flower calendar was partially affected by soil texture: flowering started on the same day for all the treatments, but in sand soil flowering ended 3 and 5 days later compared to intermediate and clay treatments respectively. Flower number and stigmas weight were significantly affected by soil texture and corm density: the greatest number of flowers and the highest total stigmas weight were found in sand soil with values +10% and +38% higher than intermediate and clay treatments, respectively. The highest corms density, that obviously determined a higher flower and stigmas production, resulted in the best production performance in both sand and intermediate soil conditions, while clay soil did not allow any increase in saffron production compared to the lowest density.