Relationship Between Assimilate Supply and Essential Oil Accumulation in Annual and Biennial Caraway (Carum carvi L.)

ABSTRACT The reported lower essential oil content of seeds of annual caraway compared with seeds of biennial caraway has three possible causes: genetic differences, differences in the location where the two types are grown, and differences in weather conditions during seed filling, since both forms of caraway ripen in a different period of the year. To study these possible causes, we compared essential oil formation in annual and biennial caraway in a greenhouse experiment, thereby excluding differences in location and weather conditions during seed filling. Surprisingly, under these conditions fruits of annual caraway had a higher dry-weight and contained more essential oil than fruits of biennial caraway. Measurement of plant carbohydrate content suggested that this was because more assimilate was available per fruit in annual caraway. It is concluded that there is no genetic barrier preventing annual caraway from reaching an essential oil content similar to biennial caraway. The low essential oil conte...