2001 Volume 3 Issue 2 Pages 81-86
The effects of wind on pollen flow depending on insect pollinators in entomophilous carrot (Daucus carota L.) plants were studied in a field, where two (2) species of syrphids (Sphaerophoria spp.) were the major pollinators and east wind of 2.5m/sec was the most common. Three (3) stecklings of the yellow root line, which is dominant to the orange root line, were planted as pollen donors at the center of the field. The pollen donors were surrounded by 12 stecklings of the orange root line as the seed parents planted at 0.5m intervals from the center in every eight directions arranged radially (Fig. 1). Seeds of two (2) flower umbels of five (5) seed parents close to the pollen donors in each direction were separately harvested and sown in a field for the estimation of the crossing rate based on the root color ratio. The two (2) flower umbels were well synchronized with anthesis of the pollen donors.
The crossing rates of the seed parents for the south and north directions at 0.5m from the center of the pollen donors were 61.4% and 82.8%, respectively, while 36.9% and 4.8% for the east and west directions, respectively (Table 1). Furthermore, the crossing rate decreased to 5-6% at a distance of more than 1.5m from the pollen donors. It was demonstrated that the main area of the pollen flow is rather small and main direction of the pollen flow forms a right angle to the wind direction when Sphaerophoria spp. are the major insect pollinators (Fig. 2).
It is concluded that in order to increase the amount of F1-seeds, the layout of planting rows of parental lines should be carefully considered in terms of planting width of the male-sterile seed parent and pollen donor as well as wind direction and visiting pollinators in the field.
