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SAFFLOWER
Carthamus tinctorius L., family Compositae

Safflower is grown principally in California and Arizona, but has been grown successfully in every State west of the 100th meridian (USDA, 1961, Dennis and Rubis 1966, Shaw and Joppa 1963, Klages 1954, Knowles and Miller 1960). The acreage varies from year to year according to the demand for safflower oil, which is obtained from the crushed seed. The oil is used in paints and in margarine and other human food. In 1963, a peak acreage of around 301,000 acres was grown. Production of seed per acre on irrigated soils has varied from 2,500 to 4,000 lb/acre; on dryland soils, from 500 to 2,500 pounds (Knowles and Miller 1965).

Safflower is frequently planted instead of barley. Although safflower is slightly more costly to produce, the same culture and harvesting equipment can be used on each. When grown in cotton-producing areas, the cotton oil mills process the seed. The residue after the oil is removed is used for livestock feed (Knowles 1955, Halloran and Kneeland 1961). The price has relatively stabilized at $80 to $90 per ton, which also amounts to about $80 to $90 per acre.

Plant:

Safflower, like other such related plants as artichoke, thistles, and star thistles, has spine-tipped leaves that make contact with the plant unpleasant. It is an upright annual, 2 to 6 feet high (fig. 171), with a coarse stem and numerous branches, each of which terminates in a yellow or orange (rarely white to red) flower head (fig. 172) from 1/2 inch to 11/2 inches across (Knowles 1958). It may be planted in rows 18 to 40 inches apart, drilled or broadcast in the field with two to six plants per square foot (Knowles and Miller 1965). The seeds ripen and are harvested 120 to 150 days after planting.

Rubis ³⁵ reported the discovery of a thin-hull mutant that produced seeds with about 10 percent more oil than earlier cultivars. The florets in this selection have delayed anther dehiscence (see "Inflorescence"), which lets the plant serve as a male-sterile line and provides a means for producing hybrid safflower.
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³⁵RUBIS, D. D. SAFFLOWER BREEDING AND GENETICS IN ARIZONA. Safflower Conf. Proc., 5pp. University of Arizona, Tucson. 1963. [Mimeographed.]

[gfx] FIGURE 171. - Safflower plant showing branching habit, spiny leaves and flowering heads.
FIGURE 172. - Safflower heads in different stages of developement. A, Head after flowering has ended; B, head in full Flower; C, bud just before first florets appear.

Inflorescence:

There may be 15 to 150 flower heads on a plant, each head enclosed in layers of spine-tipped bracts. The head that terminates the main axis of the plant flowers first, then flowering proceeds downward with those flower heads on the lowest branches opening last. On an individual plant, flowering may extend 10 to 40 days.

There may be 20 to 100 florets in a head (Claassen 1950). Those florets on the outside open first, and opening proceeds centripetally for 3 to 5 days. Within the floret, the style is enclosed by five fused anthers attached at the base by short filaments (fig. 173). The floret begins to elongate by sunrise of the day it opens. Anther dehiscence normally occurs within the fused anther tube shortly after sunrise while the style is elongating. If dehiscence occurs before the style elongates, the stigma pushes through a mass of pollen, becomes coated with pollen, and becomes self-fertilized. If dehiscence occurs after the style elongates so that the stigma passes through the anther tube without becoming pollen coated, self-sterility results. Such flowers must be visited by bees that either bring pollen from other pollen-coated stigmas or transfer pollen from within the tip of the anther tube to the stigma. The thin-hull cultivar has this delayed dehiscence and is therefore functionally male-sterile.

Nectar is secreted at the base of the filaments and is highly attractive to bees, although the quality of honey it produces is poor. ³⁶ The bee collects this nectar at the base of the anther tube from the outside rather than through the tube.

Safflower pollen is also highly attractive to bees and is considered an excellent source by beekeeping standards.
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³⁶ MCGREGOR, S. E., LEVIN, M. D., and RUBIS, D. D. BEE POLLINATION OF SAFFLOWER. Safflower Conf. Proc., 2 pp. University of Arizona, Tucson. 1963. [Mimeographed.]

[gfx] FIGURE 173. - Longitudinal section of safflower floret. A, Floret, x 6; B, filaments and adjoining area, greatly enlarged.

Pollination Requirements:

Safflower is usually considered to be a self-pollinated crop. Claassen (1950), however, reported cross-pollination ranging from zero to 100 percent, although in most of the plants he used, the detectable crossing ranged from 5 to 40 percent. Knowles (1955) reported that some selections give more vigorous progeny if open-pollinated rather than selfed. The necessity for pollen transfer by insects depends largely upon the growth characteristic of the style. If it elongates and thrusts the stigma through and beyond the anther tube before dehiscence of the pollen, then bee visitation to that stigma is necessary for maximum production (Rubis et al. 1966). If, on the other hand, dehiscence occurs before the style elongates, the stigma usually emerges thoroughly coated with pollen, and self-fertilization can result. This condition is most common in current cultivars; however, the description of the "normal" floret in India by Howard et al. (1915) indicates that delayed dehiscence, such as occurs in the thin-hull selection, may have been much more common in earlier cultivars.

Rubis (1970b) proposed a novel way to use bees to create isolation by overstocking the area with honey bee colonies that would so intensively forage an area that outside pollinators would not enter; therefore, no cross-pollination would occur. This has not been tested in practice.

The few reports on the measured value of pollinating insects to safflower are inconsistent. An extensive review of the literature on safflower by Larson (1962) revealed little on its pollination requirement. Plessers 37 reported that absence of insect pollinators caused a reduction of 47.7 and 36.5 percent in two Indian cultivars and 31.8 percent in the American cv. 'WO-14'. At least some of this reduction might be attributed to cage effect. Eckert (1962) reported lower production from plants caged to exclude bees than from open plots for one cultivar that was "somewhat self-sterile" but no difference between treatments in the "self-fertile" cultivar. Boch (1961) reported that during flowering he obtained twice as much seed from plots to which bees had access, as from plots caged to exclude pollinating insects, but again cage effect might have been a contributing factor. Patil and Chavan (1958) found that both temperature and humidity affected seed setting of bagged flowers. Kursell (1939) was reported by Claassen (1950) to have found extensive self-sterility in different lines, which, if true, would indicate that pollinating insects would have had a beneficial effect. McGregor and Hay (1952) gave a brief nod of approval to the value of pollinating insects. Rubis (1970a) indicated that commercial cultivars are from 75 to 95 percent self-fertile, indicating that their production could be improved with an ample pollinator population.

Pollinators:

Not only honey bees but various other bees and other nectar and pollen-feeding insects visit the blossoms. These may contribute in various degrees to pollination of the flower (Levin et al. 1967, Levin and Butler 1966, Butler et al. 1966, Kadam and Patanker 1942), but, in relative numbers, honey bees are by far the most important. No differences have been observed in attractiveness of different cultivars to honey bees. All seem to be attractive.

Probably, the best test of the value of pollinating insects to safflower was conducted at Tucson, Ariz. (Rubis et al. 1966). In this replicated test with two cultivars, the plots exposed to insect pollinator visitation during the flowering period were compared with plots caged under plastic screen. Pollinating insects were excluded from plants of some cages, whereas a functioning colony of honey bees was added to plants of other cages. Two lines of safflower were used: Line A was a selection from the 'Gila' cv., which normally showed about 5 percent outcrossing; line B was a composite of multiple crosses of the thin-hull selection (Rubis 1962), which normally showed about 80 percent outcrossing. The production of line A was increased about 5 percent by bees, whereas production of line B was approximately doubled.

Dennis and Rubis (1966) concluded that the benefits of honey bees or other pollinating insects to commercial cultivars depended on the amount of self-sterility or crossability in a cultivar. They stated that 'Frio' cv. was lower in self-fertility than 'Gila' cv.; therefore, yield increase from pollinating insect activity on the former would be expected to be greater. They concluded that production of 'Gila', even though it was considered to be self-fertile, could be increased 5 percent or more by honey bee pollination. Knowles and Miller ( 1965) apparently were in agreement for they stated that because safflower is not wind-pollinated, the presence of pollinating insects in abundance was necessary for maximum seed set in types that were deficient in "production" of pollen.

Pollination Recommendations and Practices:

Eckert (1959*) recommended two honey bee colonies per acre of safflower, but few, if any, growers take steps to secure this pollinator population.

Because safflower is an excellent source of nectar and pollen, beekeepers frequently place their colonies near safflower plantings, but not in the density recommended by Eckert (1959*). The data indicate that although the safflower has a high degree of fertility, the grower would profit more than the beekeeper would by having a high population of honey bees visiting his safflower blossoms.

LITERATURE CITED:

BOCH, R.
1961. HONEYBEE ACTIVITY ON SAFFLOWER (CARTHAMUS TINCTORIUS L.) Canad. Jour. Plant Sci. 41: 559-562.

BUTLER, G. D., JR., WERNER, E. G., and LEVIN, M. D.
1966. NATIVE BEES ASSOCIATED WITH SAFFLOWER IN SOUTHCENTRAL ARIZONA. Kans. Ent. Soc. Jour. 39(3): 434 - 436.

CLAASSEN, C. E.
1950. NATURAL AND CONTROLLED CROSSING IN SAFFLOWER, CARTHAMUS TINCTORIUS L. Agron. Jour. 42: 381-384.

DENNIS, R. E., and RUBIS, D. D.
1966. SAFFLOWER PRODUCTION IN ARIZONA. Ariz. Coop. Ext. Serv. and Agr. Expt. Sta. Bul. A-47, 24 pp.

ECKERT J. E
1962. THE RELATION OF HONEY BEES TO SAFFLOWER. Amer. Bee Jour. 102: 349-350.

HALLORAN, H. R., and KNEELAND, J. A.
1961. HIGH PROTEIN SAFFLOWER MEAL FOR CHICKENS. West. Feed and Seed 16(11): 23-24, 70.

HOWARD, A., HOWARD G. L. C., and KHAN, A. R.
1915. STUDIES IN INDIAN OILSEEDS. 1. SAFFLOWER AND MUSTARD. India Dept. Agr. Mem. Bot. Ser. 7: 237-272.

KADAM, B. S., and PATANKAR, V. K.
1942. NATURAL CROSS-POLLINATION IN SAFFLOWER. Indian Jour. Genet. and Plant Breed. 2: 69-70.

KLAGES, K. H. W.
1954. SAFFLOWER PRODUCTION. Idaho Agr. Expt. Sta. Bul. 222, 16 pp.

KNOWLES, P. F.
1955. SAFFLOWER-PRODUCTION, PROCESSING AND UTILIZATION. Econ. Bot. 9: 273-299. KNOWLES, P. F. 1958. SAFFLOWER. Adv. in Agron. 10: 289-323.

______and MILLER M. D.
1960. TIPS ON SAFFLOWER GROWING. Calif. Agr. Expt. Sta. Ext. Serv. Leaflet 126.

______and MILLER, M. D.
1965. SAFFLOWER. Calif. Agr. Expt. Sta. Cir. 532, 50 pp.

KURSELL, C.
1939. [BREEDING WORK ON THE NEW OIL PLANT SAFFLOWER.] Pflanzenbau 15: 463-482. [In German.]

LARSON, N. G.
1962. SAFFLOWER, 1900-1960. A LIST OF SELECTED REFERENCES. U.S. Dept. Agr. Natl. Agr. Libr. Libr. List 73 author and subject index, 557 references, 31 pp.

LEVIN, M. D., and BUTLER, G. D. JR.
1966. BEES ASSOCIATED WITH SAFFLOWER IN SOUTH CENTRAL ARIZONA. Jour. Econ. Ent. 59: 654-657.

______BUTLER, G. D. JR., and RUBIS D. D.
1967. POLLINATION OF SAFFLOWER BY INSECTS OTHER THAN HONEY BEES. Jour. Econ. Ent. 60: 1481-1482.

McGREGOR, W. G., and HAY, W. D.
1952. SAFFLOWER CANADIAN EXPERIMENTS. Sci. Agr. 32(4): 204-213.

PATIL, J. A., and CHAVAN, V. M.
1958. SELFING METHODS IN SAFFL0WER. Indian Oilseeds Jour. 2: 10-12.

RUBIS, D. D.
1962. RECESSIVE MUTANT "THIN HULL" DESCRIBED. Agron. Abstracts, p. 75.

______LEVIN, M. D., and MCGREGOR, S. E.
1966. EFFECTS OF HONEY BEE ACTIVITY AND CAGES ON ATTRIBUTES OF THIN-HULL AND NORMAL SAFFLOWER LINES. Crop Sci. 6: 11-14.

_______ 1970a. BREEDING INSECT-POLLINATED CROPS. In The Indispensable Pollinators, Ark. Agr. Ext. Serv. Misc. Pub. 127, pp. 19-24.

______ 1970b. BEE-POLLINATION IN THE PRODUCTION OF HYBRID SAFFLOWER. In The indispensable Pollinators, Ark. Agr. Ext. Serv. Misc. Pub. 127, pp. 43-49.

SHAW, A. F., and JOPPA, L.
1963. SAFFLOWER - AN OILSEED CROP. Mont. Agr. Ext. Serv. Cir. 289, 16 pp.

UNITED STATES DEPARTMENT OF AGRICULTURE.
1961. GROWING SAFFL0WER - AN OILSEED CROP. U.S. Dept. Agr. Farmers' Bul. 2133, 16 pp.

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