LUPINES
Lupinus angustifolius L., family LeguminosaeBlue lupines are grown for grazing, soil improvement, and cover, primarily in southern Georgia and northern Florida. Two decades ago, more than a million acres of lupines were grown. Since then, the acreage has dropped sharply and so have the number of species because of virus infection of the plants. Presently, some 300,000 to 400,000 acres of blue lupines are grown mostly for forage or in citrus groves (Edwardson 1963; J. R. Edwardson, personal commun., 1971).
Plant:
Blue lupines usually have upright branches, 1 to 4 feet tall, with nitrogen-fixing Rhizabium nodules on the roots, as occurs with most other legumes. The stems are relatively coarse. The seeds are relatively large, and the flowers are in large terminal or lateral racemes. The leaves may consist of 5 to 11 leaflets arising at a common point. The dense foliage will provide as much as 40,000 pounds of green manure per acre (McKee 1948).
Inflorescence:
The flower cluster is a 6- to 12-inch upright raceme, and each floret is l/2 to 1 inch in size. The petals may be shades of blue, purple, or pink. They are supposed to be nectarless but fragrant (Knuth 1908*, pp. 271 - 272; Edwardson et al. 1963), although Pellett (1947*) stated that some lupines are honey plants. The blue lupine is not a honey plant, but the pollen is attractive to bees.
The anthers dehisce before the flower opens, and after they release the pollen they shrivel, leaving the pollen in the hollow cone of the flower. When insects visit the flower, their weight causes the stamens to extrude pollen through the opening in the keel, ahead of the stigma, where pollen- carrying insects can effect crossing. Automatic self-pollination does not occur (Knuth 1908*, pp. 271 - 272). To protect the bee visitors, Edwardson et al. (1963) recommended the use of insecticides only when the bees were not visiting the plants.
Pollination Requirements:
McKee et al. (1946) and McKee and Ritchey (1947) stated that most flowers of blue, white, and yellow lupines are self-fertilized, but some crossing within (but not between) species occurs. Julen and Akerberg (1948) stated that even in some plant species considered to be self- fertilizing, seed setting is improved by insect visits This applies particularly to yellow lupine.
Kozin (1967) found that visits by honey bees substantially increased the number of pods set in three of five cultivars, the length of pod in 7 of 13 cultivars, the number of seed in all cultivars tested but three, and the weight of seed for all cultivars but two. The visits also increased the germination qualities of the seed Wallace et al. (1954) quoted Troll (1948) as saying that cross-pollination is always more frequent in yellow lupine than blue and that the extent varies with the distance to the nearest apiary. They showed practically no hybrids resulted from bee activity on blue lupines but 19.9 percent from plants of yellow lupine, both oi which were only a quarter of a mile from an apiary They also noted that honey bees work the sweet yellow lupines. Forbes et al. (1971) concluded that blue lupine is highly self-compatible, and fully capable of self-poll) nation in closed flowers independent of insect pollina tion. However, their data show that both 'Rancher' and '65G-251' selections produced more seed when there was no barrier to pollinating insects than when either poultry wire of 2.5 cm mesh or fine screen enclosed the plants. This would indicate that insects have a beneficial effect.
Pollinators:
Kozin (1967) showed that honey bees represented 83 percent, bumble bees 9.6 percent, and other insects 7.4 percent of the visitors to "fodder" lupine. He further noted that 56.5 percent of the bees collected pollen and inserted their proboscis into the flower. Leuck et al (1968) also considered the honey bee to be the most important pollinator on blue lupine. Forbes et al (1971) considered neither bumble bees nor thrips of consequence and attributed the range of crossing the observed (from 0 to 12.0 percent) to known honey bee population densities.
The honey bee, then appears to be the primary flora visitor. Kozin (1967) recommended that honey bees be widely used for increasing the seed crop of lupines, but the species of lupines involved was not given. Thorp (1957*) listed white, yellow, and blue lupines under the heading "Seed Production Increased by Bees." Horovit and Thorp (1970) considered the bumble bee to be better than the honey bee in the pollination of L. nanus Dougl.
Pollination Recommendations and Practices:
None.
LITERATURE CITED:
EDWARDSON, J. R.
1963. RITCHEY- AN IMPROVED SEED PRODUCING VARIETY OF BITTTER BLUE LUPINE. Fla. Agr. Expt. Sta. Cir. S-143, leaflet._____WELLS, H. D., and FORBES, I., JR.
1963. BLUE LUINES FOR GRAZING AND FOR SOIL IMPROVEMENT IN FLORIDA. Fla. Agr. Expt. Sta. Cir. S-146, 7 pp.FORBES, I., LEUCK, D. B., EDWARDSON, J. R., and BURNS, R. E.
1971. NATURAL CROSS-POLLINATION IN BLUE LUPINE (LUPINUS ANGUSTIFOLIUS L.) IN GEORGIA AND FLORIDA. Crop Sci. 11: 851-854.HOROVITZ, A., and THORP, R. W.
1970. BEES AS TOOLS IN STUDIES OF REPRODUCTIVE BIOLOGY OF PLANTS.] Amer. Midland Nat. 84: 560-563.JULEN, G., and AKERBERG, E.
1948. [INSECTS AND SEED SETTING IN AGRICULTURAL PLANTS.] Svensk Jordbr. Forsk. Arsbok: 86-97. [In Swedish.] Abstract in Herbage Abs. 18(4): 899, Aug. 1948.KOZIN, R. B.
1967. INFLUENCE OF BEE (APIS MELLIFERA) POLLINATION OF LUPINE (LUPINUS L.) ON SEED YIELD AND QUALITY. In 21st Internatl. Apic. Cong. Proc., Aug., College Park, Md., p. 481.LEUCK, D. B., FORBES, I., BURNS, R. E., and EDWARDSON, J. R.
1968. INSECT VISITORS TO FLOWERS OF BLUE LUPINE (LUPINUS ANGUSTIFOLIUS). Jour. Econ. Ent. 61: 573.MCKEE, R.
1948. THE LEGUMES OF MANY USES. U.S. Dept. Agr. Yearbook 1948: 701-726._____HYLAND, H. L., and RITCHEY, G. E.
1946. PRELIMINARY INFORMATION ON SWEET LUPINES IN THE U. S. Amer. Soc. Agron. Jour. 38: 168-176._____and RITCHEY, G. E.
1947. LUPINES, NEW LEGUMES FOR THE SOUTH. U.S. Dept. Agr. Farmers' Bul. 1946, 10 pp.TROLL, H. J.
1948. [PROBLEMS IN THE DEVELOPEMENT AND BREEDING OF THE MUNCHBERGER LUPINES. Der Zucher 19: 153-177. [In German.]WALLACE, A. T., HANSON, W. D., and DECKER, P.
1954. NATURAL CROSS-POLLINATION IN BLUE AND YELLOW LUPINES. Agron. Jour. 46: 59.
