Experiments on carrot seed growing. I

Effects of pruning and rainfall on yield of carrot seed and its germinability

Abstract

Poor germination of carrot seeds is an important problem for both seedmen and carrot growers. The author tried to elucidate what factors are the causes of the poor germination in the carrot seed production.
Control of number of umbels per plant by pruning resulted in the increase in seed weight and seed size, bnt did not improve germinability of seeds.
When the umbels were harvested separately, the germinability of seeds in the first order umbels was highest, that in the second order umbels next, and that in the third order the lowest. But in the seeds grown under glass, difference was scarecely found among the seeds in the umbels of different orders.
In order to clarify the effect of rainfall during seed maturing, carrot plants grown in one foot diameter clay pots were transferred into the glasshouse at different stages of seed development, from flowering to firm brown seed stage. Rainfall at the flowering stage often made the flowers sterile and that at the ripening stage lowered the seed germinability.
Early flowering plants produced seeds of higher germinability than late flowering ones did.
Judging from these results, the seed germinability in the third order umbels, which flower latest, is decreased by rainfall and high temperature at their ripening stage.
For the purpose of improving the germinability of carrot seeds, therefore, it is advisable to prune off the umbels so as to leave only the umbels of the second order in such cases as in the variety “Kuroda” in Kyushu.