TURNIP AND RUTABAGA
Brassica rapa L., and B. napobrassica Mill., family CruciferaeTurnip (B. rapa) and rutabaga (B. napabrassica) are sufficiently alike from the botanical and pollination standpoints to be combined. Turnips are about 10 times as important as rutabagas. About as much turnip as radish seed is produced annually, 1,500 to 3,000 acres. Seed production is primarily in the Pacific Northwest (Hawthorn and Pollard 1954*).
Plant:
The plants of the two species are grossly similar except that the turnip has prickly leaves, whereas those of the rutabaga are glabrous (smooth). Turnip leaves arise from a smaller neck than that of rutabaga leaves, and the turnip blossoms have brighter more yellow flowers than those of the rutabaga.
The plants are biennial, each producing a fleshy, edible, globular root, 2 to 6 inches thick. The first year the growth above ground consists of a rosette of leaves about a foot across. A main flowering stem, 21/2 to 4 feet long, and its branches develop the second year. The rutabaga root is somewhat larger than the turnip root. Rutabagas grow more slowly than turnips (Jones and Rosa 1928*). The plants cross readily.
Inflorescence:
The flowers of turnips and rutabagas are identical in structure to those of other Cruciferae (see "Cole Crops"). The main flowering stem is also similar, but the 3/8-inch flowers of rutabaga are less golden than turnips, rape, or mustard. The flowering period lasts 22 to 30 days. A single bloom will last 2 or 3 days if pollinated, but if caged so that bees are excluded, it may stay open as long as 12 days (Nikitina 195O). Both turnips and rutabagas provide a good source of nectar for bees.
Pollination Requirements:
Pollination is a requisite to good seed production in both turnips and rutabagas but more so in turnips. Nikitina (1950) reported that turnips isolated from bees produced only one-third as much seed as open- pollinated plants. Also, the seeds from the bee-pollinated plants had better germination and produced more vigorous plants. Jones and Rosa (1928 *) stated that cross-pollination was more essential in turnips than rutabagas, and more essential in white-fleshed than yellow- fleshed turnips. Hawthorn and Pollard (1954*) stated that to insure a good seed set, the pollination of all the flowers is necessary.
Pollinators:
Nikitina (1950) stated that in Russia 60 percent of the floral visitors to turnips and rutabagas were honey bees. He reported yields of 450 to 560 kg seed per ha, where there were 67 colonies and 10 acres of the crop. Farms with fewer colonies produced less. Hawthorn and Pollard (1954*) stated that honey bees are the chief pollinators.
Pollination Recommendations and Practices:
Hawthorn and Pollard (1954*) stated that with large plantings the grower should make sure that colonies of bees are adjacent to the field. They did not say how many colonies were needed. However, to obtain the pollination of all the flowers, which they stated was necessary for a good seed set, one or more colonies per acre would doubtless be required, the number depending, as in other crops, upon plant competition, colony fitness, and crop condition.
LITERATURE CITED:
NIKITINA, A. I.
1950. [HONEY BEES RAISE SEED YIELDS OF TURNIP AND RUTABAGA.] Pchelovodstvo 5: 271-274. [In Russian.]
