Carthamus tinctorius (PROSEA)
- Protologue: Sp. pl. 2: 830 (1753).
- Family: Compositae
- Chromosome number: 2n= 24
- Safflower, false saffron (En).
- Carthame (Fr)
- Indonesia: kasumba (general), kembang pulu (Javanese), rale (Buginese)
- Malaysia: kesumba
- Philippines: kasubha (Pilipino, Tagalog), kasabha (Bisaya), kasaba (Ilokano)
- Thailand: kham (general), khamfoi (northern), kham yong (Lampang)
- Vietnam:hồng hoa; cây rum.
Origin and geographic distribution
Safflower is known only from cultivation and probably originated in the Middle East. Other centres of diversity are Afghanistan, Ethiopia and India. It has long been domesticated, initially for the orange dye obtained from the florets. It was identified as growing in Egypt in 2000 BC. Its use as an oil crop probably came later, but also dates back to pre-Christian times. The "Revenue papyrus" of Ptolemy II of 259-258 BC states that the king had a monopoly of production and marketing of safflower along with sesame and castor oils. Safflower was probably introduced into China around 200-300 AD, where it was initially cultivated for its dye. It was grown extensively in many areas, particularly along the Chang Jian (Yangtze river) and in Sichuan (Szechwan). Safflower was introduced into Japan from China probably about the third Century AD. The oil was little used in cooking until the 20th Century, but it is now a major import in Japan. From the Middle East, the crop also spread westward into Europe and the Americas. It is grown on a small scale throughout South-East Asia, where it is most important in Thailand.
The edible oil extracted from the seed is now the main product of safflower. Although the oil is suitable for paint production, it is used almost exclusively in cooking, making salad dressings and margarine. Cultivars with a high oleic acid level make safflower oil a major olive oil extender, one of the reasons for the crop's rapid expansion in Spain. In Australia, cultivars yielding oil with a high linoleic acid content are preferred. The oil has industrial uses.
Safflower has long been grown for the dye extracted from the florets. Depending on the dyeing procedure and the addition of other colourants and mordants, it imparts a yellow, red, brown or purple colour to cloth. With the introduction of cheap synthetic dyes, its importance as a dye source has greatly declined. However, dyes are still produced on a small scale for traditional and religious purposes. As a natural food colourant it is a substitute or adulterant for true saffron. Florets are commonly mixed with rice, bread, pickles and other food to give them an attractive orange colour.
The seed cake can be used as animal feed. Increased protein and lysine content, reduced fibre content and the removal of the bitter principle matairesinol monoglucoside make safflower meal more attractive to stock feed manufacturers. Safflower meal and flour from decorticated seeds are high-protein human diet supplements. The flour can be added to wheat flour to make breads and pies.
In Asian countries, the young leaves are eaten as a vegetable and seeds are used in cooking and as bird feed. Safflower herbage is valuable as green fodder or stored as hay or silage.
Safflower has a prominent place as a cosmetic ingredient and to a minor extent in medicine. In China, the flowers are used to treat illnesses such as cerebral thrombosis, male sterility, rheumatism and bronchitis, to induce labour and as a tonic tea to invigorate blood circulation and the heart. Safflower-based medicines also show beneficial effect on pain and swelling associated with trauma.
Production and international trade
World production of safflower has steadily declined since the mid-1970s, when world production of oil was about 630 000 t and exports about 210 000 t. The decline was mainly due to competition from hybrid sunflower and brassica oilseed and the great expansion of soya bean production in South America. Major producers of safflower are India, the United States, Mexico, Kazakhstan, Ethiopia, Argentina, Australia and China. Most growers now market their crop domestically and only export the surplus.
Fruit of white-hulled commercial safflower is composed of hull 30-40% and seed (kernel) 60-70%. The seed may contain 35-60% oil. The proportion of hull was higher in the past and a handicap to commercial production, but the introduction of thin or reduced hulls may hamper mechanical harvesting and processing. The seed contains a drying oil and the average unsaturated fatty acid composition of commercial safflower oil is: oleic acid 10-15%, linoleic acid 70-80% and traces to zero of linolenic acid. The saturated fatty acids are palmitic acid 5-7% and stearic acid 2-3%. However, differences between cultivars are large: cultivars classified as containing very high linoleic acid have 5-7% oleic acid and 87-89% linoleic acid, while high oleic acid cultivars contain 75-80% oleic acid and 14-18% linoleic acid. Safflower oil is stable and does not alter at low temperatures or when heated. It is pale or golden yellow and has a bland or nutty flavour depending on the processing method. The oil’s high linoleic acid content, low colour values, low free fatty acids, low content of unsaponifiable compounds and absence of linolenic acid and waxes make it suitable for the production of high quality paints, alkyd resins and coatings. After oil extraction from undecorticated safflower, the residual cake contains: protein 20-22(-25)%, hull 60%, residual fat 2-15% and crude fibre 30-40%. The presscake from decorticated fruit contains up to 42% protein. This high fibre content limits its value as livestock feed, but removing the hulls may be too costly. Undecorticated meal can be used only to supplement a grain, lucerne and silage ration to fatten cattle. It cannot be fed to pigs, except in small quantities, nor to poultry. However, hulled seedmeal with a good protein supplement can be given to pigs.
The florets of safflower contain two major pigments: the water-soluble, yellow carthamidin and the formerly important dye carthamin, which is orange-red and soluble in alkaline solutions. Florets have 0.3-0.6% carthamin. Flavonoids, glycosides, sterols and serotonin derivatives have been identified from the florets and seeds. Some of them, e.g. matairesinol, may have medicinal properties.
The 1000-seed weight is 40-80(-100) g.
- Erect, much-branched, glabrous, annual herb, 30-180 cm tall. Root system well developed, brownish-greyish, taproot thick and fleshy, penetrating up to 3 m depth, horizontal laterals thin, occurring mainly in the upper 30 cm. Stem cylindrical, solid with soft pith, woody near base, striate, greenish-white.
- Leaves spirally arranged, sessile, exstipulate; blade oblong to ovate-lanceolate, 4-20 cm × 1-5 cm, lowest ones largest, margin spinose-dentate, glossy dark green, herbaceous when young, turning firm and stiff.
- Inflorescence a terminal, urn-shaped head, about 4 cm long and 2.5-4 cm in diameter, containing only disk florets; involucral bracts numerous, spirally arranged, outer ones oblong, constricted above the base, 3-7 cm × 0.5-1.6 cm, upper part leafy and spinescent, erect or spreading, not appressed, with long hairs on the lower margin, lighter green than the leaves, lower part appressed, whitish-green, long-hairy outside, especially on the margin, glabrous inside; towards the centre of the head, the constriction becomes less apparent and the leafy part disappears; innermost bracts lanceolate, 2-2.5 cm × 1-4 mm, apex spinescent, ciliate; receptacle flat to conical, with abundant, erect, whitish bristles 1-2 cm long and 20-80 bisexual florets (a few marginal ones sterile).
- Floret tubular, sessile, actinomorphic, about 4 cm long, glabrous, mostly orange-red becoming dark red during flowering, sometimes yellow; corolla 5-lobed, tube 18-22 mm long, lobes spreading, narrowly oblong to linear, 7 mm × 1 mm; stamens 5, epipetalous, inserted at the mouth, filaments 1-2 mm long, anthers 5 mm long, connivent, forming a column; ovary ellipsoid, 3.5-4.5 mm long, one-celled, one-ovuled, bearing a disk on top; style slender, 28-30 mm long, glabrous, pushing up through staminal column; stigma 5 mm long, bifid, yellow, with short hairs.
- Fruit an achene, obovoid, often obliquely so, 5.5-8 mm × 3-5 mm, 4-angled with clearly visible ribs, glabrous, glossy white but often pale brown near top, sometimes with a pappus; pappus variable from head to head and from fruit to fruit, generally the innermost fruits in a head bearing the biggest pappus, the outermost ones none; a fully developed pappus consists of several complete, dense circles of paleae clasping the scar of the corolla; paleae narrowly oblong to linear, 6 mm × 0.2 mm, white, glabrous, flat, base bent inwards, margin ciliate, apex obtuse or acute.
- Seed exalbuminous.
- Seedling with epigeal germination, strong taproot, hypocotyl greenish-white; cotyledons leaflike, obovate, 3 cm × 1 cm when plumule starts growing, 6 cm × 1.5 cm when full-grown, greyish pale-green, when young with darker green dots; first leaves lanceolate with tapering base.
Growth and development
After germination the seedling enters the rosette stage, characterized by slow growth, production of many leaves near the ground surface and development of a deeply penetrating taproot. When sown in spring, safflower generally has no rosette stage, while a long rosette stage occurs when it is autumn-sown. During the rosette stage plants are tolerant of frost, allowing them to overwinter. Safflower is a long-day plant. Flowering is normally initiated by approximately 14 hours of daylight, but this can be modified by temperature, high temperature accelerating flowering. Salinity and cultivar type may also accelerate the onset of flowering. Daylength neutral cultivars also exist. In contrast to its relatively slow initial growth, safflower grows rapidly after the stem begins to elongate. When the plant is 20-40 cm tall, lateral branches start to develop. Stem elongation and branching are followed by the development of a flower head at the tip of each stem. After the completion of growth of secondary branches and the formation of flowering heads (75-100 days after sowing), florets start to appear in the heads. Flowering begins in the head of the main axis, followed by the most mature of the main branches; secondary and tertiary branches follow sequentially. Flowering normally begins at the head’s margin, proceeds centripetally and takes 3-5 days to complete. Total flowering extends over 10-40 days. Safflower is basically self-pollinated, pollination ensuing as the style and stigma grow through the surrounding anther column at the base of the corolla. However, a high degree of crossing can occur, particularly in thin-hulled types. Bees or other insects are generally necessary for optimum fertilization and maximum yields. Male and female sterility occurs. Structural male sterility is linked with the thin-hull character and delayed anther dehiscence in this type is used to produce hybrid seed. A well-developed safflower head contains 15-30 or more achenes which mature in 4-5 weeks after flowering.
Other botanical information
Because C. tinctorius has been cultivated over a wide area since ancient times, and because cross-pollination is fairly common, variability in safflower is great. The morphological differences are most obvious in branching (height, density), the leaves (presence or absence of rosette leaves, armed or unarmed leaves), involucral bracts (form, pubescence, spiny or entire margins), number and size of heads per inflorescence, flower colour (reddish, orange, yellow, white), and fruit (achene) (size, presence or absence of pappus). For oil crops, ecological differences allow distinction of 3 types of populations: early ripening (small bushy plants), late ripening (medium large plants) and very late ripening (tall plants). Several botanical varieties have been distinguished in the literature on safflower, but as safflower is known only from cultivation, a classification system into cultivars and cultivar groups would be most suitable but does not yet exist. In India, the former Soviet Union and the United States many cultivars are known. The primary uses of the cultivars could define the major groups, such as cultivars for oil production, forage production or ornamental purposes.
Safflower is closely related to the wild, diploid (all 2 n = 24), annual species C. curdicus Hanelt (western Iran), C. gypsicolus Ilj. (from the Caspian Sea to the Aral Sea), C. oxyacanthus M. Bieb. (from Iran and Iraq to north-western India), C. palaestinus Eig (desert areas from southern Israel to western Iraq) and C. persicus Willd. (syn. C. flavescens auct., non Willd.) (Turkey, Syria, Lebanon). It is thought that C. palaestinus (self-compatible) is the progenitor of the weedy species C. oxyacanthus (mixture of self-compatible and self-incompatible types) and C. persicus (self-incompatible) and these weedy species are thought to be the parental species of C. tinctorius ; these 4 species can intercross in all combinations and produce fertile hybrids and it is possible that introgression of the weedy and cultivated species may still take place (natural hybrids occur). C. nitidus Boiss., another diploid species with 24 chromosomes, is difficult to cross with safflower and the hybrids are sterile. The crossing possibilities of C. tinctorius with C. curdicus and C. gypsicolus are not known. Other Carthamus species are less related to safflower and have different chromosome numbers. The taxonomy of Carthamus is still under discussion, both at species and genus level. In a wide genus concept, about 50 species are accepted; in a narrow concept about 15 annual species remain in Carthamus , while the perennial taxa are classified in other genera including Carduncellus Adans., Femeniasia A. Susanna de la Serna, Lamottea Pomel and Phonus J. Hill.
Safflower is basically a crop of semi-arid, subtropical regions, but its range has been greatly expanded by selection and breeding. It is distributed within latitudes 20°S and 40°N and its cultivation has recently even spread into Canada. In the tropics it is mostly grown at 1600-2200 m altitude, but large-scale commercial production is concentrated in semi-arid areas below 1000 m. Seed yield and oil content fall with increasing altitude. Seedlings can tolerate -7°C, some cultivars even down to -12°C. They become more susceptible to frost damage after the rosette stage. Average temperatures of 17-20°C appear to be best for vegetative growth, while the optimum temperature for flowering ranges from 24-32°C. Adequate soil moisture reduces the adverse effect of higher temperatures.
Safflower requires about 600 mm of rainfall with a major portion falling before flowering. Under dry, windy conditions, which are most suitable for safflower production because of the low disease incidence, 800-1000 mm are required. In places where there are no hot, dry winds, reasonable yields can still be produced as long as 300 mm of rain is available before flowering. Because of its extensive root system, safflower can be grown largely on residual soil moisture. If pre-planting soil moisture covers about two-thirds of the total water requirement, the remainder can be supplied by rainfall.
In the United States and Australia, 1500-2500 mm of irrigation water is required to produce a high-yielding commercial crop. In Israel, safflower needs a minimum of 600 mm rain plus a similar amount from irrigation. In Tanzania, 400 mm rainfall plus 450 mm irrigated water are the minimum requirements but crops supplied with 2250 mm of irrigation water in the dry season produce twice the wet season yield, partially due to less damage from diseases and pests. A rain-fed crop in India requires 650-1000 mm, but in the dry season under irrigation, it needs 1800-2100 mm (less if the preceding crop is rice).
Safflower is grown by smallholders on a wide range of soils with pH 5-8. For large-scale production, fairly deep, well-drained, sandy loams of neutral reaction are preferred. Highest yields are obtained in dry regions on sandy loams with irrigation. Regardless of their fertility, shallow soils seldom produce high yields, and this is invariably due to insufficient moisture. Safflower is considered to be salt-tolerant, although many commercial cultivars are salt-sensitive. It is especially tolerant of sodium salts, but less so of calcium and magnesium salts. Salinity delays initial seedling emergence, while very high levels reduce germination. However, safflower is a suitable crop for saline soils, especially the recent highly salt-tolerant cultivars.
Propagation and planting
Chisel ploughs or subsoilers should be used to fracture compacted soil layers within the root zone because safflower is deep-rooted. Ideally, safflower should be sown 3-5 cm deep into moist soil, but when topsoil is dry and loose, seed may be planted 10-15 cm deep. Most seed drills are suitable for sowing safflower, but should be recalibrated. It is sometimes recommended that furrow-openers be fitted to seeder units and the furrows to be only partially closed after sowing. Seed rates depend on cultivar and growing conditions. For large-scale rain-fed crops seed rates average 30 kg/ha, under irrigation 60 kg/ha. Wide rows, 35-60(-90) cm with close in-row spacing generally gives the highest yield. Safflower can compensate for spatial variation by producing more secondary and tertiary heads per plant. However, while the seed yield may be little affected, less oil will be produced as seeds from these heads are generally smaller and have a low oil content.
Safflower is readily integrated into mechanized small grain production. Mechanical weeding of young safflower is difficult, and pre-planting cultivation should aim at maximum weed reduction. A light harrowing before emergence effectively kills young weeds. While safflower is still small, finger weeders and rotary hoes can be used, but when plants reach about 15 cm in height, weeding should be limited to the inter-row. However, careful hand weeding gives the highest yield. Pre-emergence herbicides combined with mechanical inter-row weeding are widely used in commercially grown safflower, but no effective post-emergence herbicide is available.
Nitrogen is the most important nutrient, phosphate requirement is moderate, and potassium is required only where there is a major local deficiency. At the levels normally applied, fertilizers generally have little direct effect on seed composition or oil percentage. However, by increasing seed yield, they increase total oil yield. Contact between seedlings and fertilizer should be avoided and N applications split when the rate is above 100 kg N/ha. Up to 150 kg N/ha is applied to current high yielding cultivars grown under irrigation. When rain-grown, these cultivars are given about 50 kg N/ha. Phosphate fertilizers are normally residues from animals and crops or rock phosphate. However, 5-12.5 kg P/ha has been recommended for smallholder crops in India, Iran, Pakistan and Afghanistan.
Intercropping safflower is possible, but not common in smallholder fields because the yields are low as a result of crop competition. Safflower should not be planted on the same land for two consecutive years because it is susceptible to soil-borne fungal diseases.
Diseases and pests
Many diseases have been recorded on safflower, but few limit commercial production. Rust, caused by Puccinia carthami, is the most important disease attacking young safflower. Foliar diseases are prevalent in places where rainfall occurs between the late bud stage and near maturity and the most serious and widespread is leaf blight caused by Alternaria carthami. Root rots caused by Fusarium oxysporum and Phytophthora spp. including P. cryptogea and P. drechsleri are widespread and very damaging. P. drechsleri causes a serious disease of surface-irrigated safflower and its incidence and severity is increased if the crop has undergone moisture stress.
The majority of insects that attack safflower are of little economic importance and do not require control. Perigea capensis attacks at all stages of development and is common in South-East Asia, India and Pakistan. Bollworm (Helicoverpa spp.) occurs in all countries that grow safflower and it may be of varying importance. However, specific insects such as the safflower fly (Acanthiophilus helianthi) can virtually preclude safflower growing. It is necessary to balance chemical control against allowable damage because complete control is seldom possible or profitable in safflower cultivation.
Harvesting of safflower usually begins 35-40 days after maximum flowering, when plants are quite dry but not brittle, bracts on heads turn brown and fruits have a moisture content below 8%, preferably 5%. Grain combine harvesters are quite suitable although they cannot cut as fast as in wheat or barley. Harvesting safflower is comparatively simple since the crop does not generally lodge or shatter. A mature crop is relatively immune to damage and may be left standing in the field for one month with little loss. Light cold rain or frost does little damage. However, certain cultivars germinate in the head if periods of warm wet weather occur at maturity. For smallholders, the extended harvesting period allows individual heads to be collected as they ripen. Generally, however, plants are uprooted, heaped and dried in the field for a few days and threshed to remove the seeds.
For the dye production, flower heads are collected every second to third day before they fade. Harvested florets are washed and later dried.
The average yield of safflower grown under rainfed, intensive cultivation has increased steadily to 1500 kg/ha and nearly twice this under irrigation. Average yields in India are about 500 kg/ha.
Handling after harvest
Safflower fruit can be stored in bulk, where possible in grain bins, provided the seed moisture content is 5-8%. Safflower can be processed by most commercial oilseed plants either by pressure, solvent extraction or a combination of both. There are no special requirements. Carthamin is extracted from the flowers by first washing out the cathamidin in ample water and subsequently extracting the flowers with a sodium carbonate solution. Carthamin is precipitated from the solution using diluted acid.
Considerable research into safflower's genetics and breeding has been carried out, including work on many related species considered valuable sources of genetic material. A gene bank is maintained by the United States Department of Agriculture at Washington State University, a world germplasm collection at Solapur, India and major collections in China, Ethiopia, Israel, Pakistan, Spain and the Russian Federation.
Reducing the hull percentage is a major objective in breeding safflower. Current cultivars with less fibre (17% of the fruit and 38% of the seed) and a higher protein content are preferred by stock feed manufacturers. Seed composition, oil content and quality (in terms of component fatty acids) are influenced by environment, including latitude, altitude, day and night temperatures and amount of rainfall during flowering and seed setting.
The discovery of a gene causing partial male sterility allowed more detailed study of heterosis and related processes. A mass emasculation technique has been developed, and in vitro techniques enable large-scale production of selected strains. A variety of other methods under the general heading of genetic engineering are reported. There is a major need to expand safflower’s adaptation through genetic research and breeding.
The use of dyes from natural sources in food products is gaining popularity because of possible harmful effects from synthetic colourings. In industrialized nations where research has linked health and diet, demand for unsaturated oils has increased, thereby creating a growing market for such oils as health foods, especially in North America, Germany and Japan. Both trends may lead to an increasing demand for, and production of, safflower.
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L.P.A. Oyen & B.E. Umali