SEED YIELD IN CARAWAY (CARUM-CARVI) .1. ROLE OF POLLINATION

Seed yields of caraway vary considerably between years, indicating that weather affects the yield-determining processes. Pollination could be one of these processes, because pollinator activity and efficiency are negatively affected by cold or wet weather. From 1990 to 1992 at the Research Institute for Agrobiology and Soil Fertility in Wageningen, The Netherlands, held and glasshouse experiments were performed to study the importance of pollination for caraway seed yields and the effects of some environmental factors. Preventing insect pollination by placing gauze cages in field plots reduced the yield of caraway by c. 15-20 %, but under normal field conditions > 90 % of hermaphrodite flowers were fertilized and additional hand-pollination did not improve yield. Removal of competing umbels enhanced the low seed set percentages in higher-order umbels, indicating that pollination did not limit seed yield in these umbels. Assays suggested that wind transfer, in addition to insects, plays a role in the pollination of caraway. It was concluded that assimilate availability and not pollination limits caraway seed yield.