EN
Variation in the level of self-incompatibility (SI) was quantified in 14 Polish lines of cabbage (Brassica oleracea L. var. capitata) pollinated in various temperature/humidity conditions. Two methods were used to measure the expression of incompatibility: counts of seed set and counts of pollen tubes penetrating the styles 48 h after self-pollination. The level of self-incompatibility varied distinctly depending on the cultivar (from 0 to 65% seed-containing siliques). The genetic background of the material determined the influence of environmental factors on SI. Lower temperature (12°C) and higher humidity (90%) positively affected bud pollination, possibly due to a less stressful protocol. The observed great genotypic variation suggests it may be difficult to find a universal method suitable for breaking the self-incompatibility barrier for the species. The method may have to be tailored to the particular genotype.