BEET
Beta vulgaris L., family ChenopodiaceaeThe term "beet" is used to include both the garden beet and sugar beet grown in the United States. The former were grown on 17,930 acres in 1969 and were valued at $4.8 million; the latter were grown on about 1.5 million acres with a farm value of $353 million.
Plant:
The beet is normally an herbaceous biennial. The first year it develops a rosette of large leaves and a fleshy root. The second year it develops a seed-stem, which draws upon the food stored in the root, and after the seed crop is produced the entire plant dies. The whitish root of the sugar beet (from which sugar is obtained) may be 6 to 8 inches thick and up to 2 feet long. The reddish garden beet root is more or less oval and 2 to 4 inches across. The leaf of the sugar beet rosette may reach 2 feet high by 6 to 8 inches across. The garden beet leaves are much more delicate. Whether the plant is grown for its root as a vegetable or as a source of sugar, the growth characteristics are similar. The second year the seed-stem appears and a seed crop is obtained. Both types of beets are cultivated in rows.
Inflorescence:
The many-branched seed stem, which produces the inflorescence and which may reach 4 to 6 feet, is composed of large particulate open spikes. The small, greenish, sessile flowers (fig. 49) are usually in clusters of two or three, one of which bears a single, extended bract. The flowers are perfect although they rarely self, because the stigma is not fully mature when the flower opens (Artschwager 1926). The flower opens in the morning, and the anthers dehisce before noon. The stigmatic lobes open gradually in the afternoon and are not fully open until the second or even the third day. By then, the anthers of the same flower have shriveled and no longer produce pollen. Once open, the stigma may then be receptive for more than 2 weeks. Shaw (1914) indicated that a pungent nectar is present and that there is an abundance of pollen. Jones and Rosa (1928*) also reported that a large amount of pollen is produced, which is carried long distances by wind. Meier and Artschwager (1938) reported that beet pollen was collected by airplane 5,000 m above beet fields.
[gfx] FIGURE 49. - Longitudinal section of beet flower, x 33.
Pollination Requirements:
Poole (1937) stated that the beet is an example of a wind-pollinated species that is also insect pollinated to some extent. Shaw (1916) stated that self-incompatibility seemed to be the general rule in beets. Owens (1945) reported that male-sterility existed in sugar beets. Mikitenko (1959) trained bees to collect nectar from beets, which resulted in an increase in seed production of 14.3 percent compared with the control. Stewart (1946) concluded that wind alone is sufficient to transfer the pollen from anthers to stigmas, but unfortunately the conclusion was based on production of plants in the open compared to plants in cages that excluded larger insects. No attention was paid to "larger insects" on the open plants or to small insects in the cages.
Although beets are basically wind pollinated, some benefit may be derived from insect pollination. The lengthy period that the stigma is receptive to pollen doubtless contributes to the chances that windborne pollen will encounter it in time to effect fertilization and the production of seed.
Pollinators:
Wind is doubtless the major pollinating agent of beets. However, Shaw (1914) reported that thrips cross-pollinate some flowers. Treherne (1923) considered syrphids the most prevalent cross-pollinating insects present on beet flowers, but honey bees, solitary bees, and various Hemiptera were also important. Sharma and Sharma (1968) reported that honey bees were "prominent" on sugar beet flowers. Popov (1962) (according to Free 1970*) stated that Halictidae, Megachilidae, and Anthophoridae were most abundant on beet flowers. Mikitenko (1969) and Archimowitsch (1949) reported that bees will visit beets in large numbers for pollen if nothing else is available, and Mikitinko (1969) stated that they may increase yield of beet seeds. The finding of numerous honey bees or wild bees on beet flowers in the United States is unlikely if there is other pollen available in the area.
Pollination Recommendations and Practices:
Although the evidence indicates that pollinating insects may cause some increase in beet seed yields, their value is given no consideration in the usual recommendations for beet seed production. The evidence indicates that they may be beneficial, and for that reason their activity in flowering beet fields should be encouraged.
LITERATURE CITED:
ARCHIMOWITSCH, A.
1949. CONTROL OF POLLINATION IN SUGAR BEETS. Bot. Rev. 15: 613-628.ARTSCHWAGER, E.
1926. DEVELOPMENT OF FLOWERS AND SEED OF SUGAR BEETS. Jour. Agr. Res. 34: 1-25.MEIER, F. C., and ARTSCHWAGER, E.
1938. AIRPLANE COLLECTION OF SUGAR BEET POLLEN. Science 88: 507-508.MIKITENKO, A. S.
1959. [BEES INCREASE THE SEED CROP OF SUGAR BEET.] Pchelovodstvo 36(5): 28-29. [In Russian.] AA-356/60.OWENS, F.V.
1945. CYTOPLASMTCALLY INHERITED MALE-STERILITY IN SUGAR BEETS Jour. Agr. Res. 71: 423-440.POOLE, C. F.
1937. IMPROVING THE ROOT VEGETABLES. U.S. Dept. Agr. Yearbook 1937: 300-325.POPOV, V. V.
1952. [APIDAE POLLINATORS OF CHENOPODIACEAE.] Zool. Zhur. 31: 494-503. [In Russian] , Cited by Free (1970 *).SHARMA, P. L., and SHARMA, B. R.
1968. ROLE OF INSECTS IN THE POLLINATION OF DAUCUS CAROTA (CARROTS) AND BETA VULGARIS (SUGAR BEET). Indian Jour. Hort. 25(3/4): 216.SHAW, H. B.
1914. THRIPS AS POLLINATORS OF BEET FLOWERS. U.S. Dept. Agr. Bul. 104, 12 pp._____ 1916. SELF, CLOSE AND CROSS-FERTILIZATION OF BEETS. N.Y. Bot. Garden Mem. 6: 149-152.
STEWART D.
1946. INSECTS AS A MINOR FACTOR IN CROSS POLLINATION OF SUGAR BEETS. Amer. Soc. Sugar Beet Tech. Proc. 4: 256-258.TREHERNE, R. C.
1923. THE RELATION OF INSECTS TO VEGETABLE SEED PRODUCTION. Quebec Soc. Protect. Plants Ann. Rpt. 15: 47-59.
