Searching for an alternative oil crop for organic farming systems in temperate climates
Weber, E.A.1, Elfadl, E.2, Reinbrecht, C.3, Graeff, S. 4 & Claupein, W.5
Key words: safflower, accessions, selection, seed yield, oil content
Safflower is an oil crop widely grown in semiarid and arid regions whose oil is valuable because of its high concentration of polyunsaturated fatty acids. The aim of this contribution is to give an overview of the methods for identifying potential genotypes suitable for cultivation in temperate climates. From 2002 to 2005 a great many safflower accessions from a worldwide safflower collection were screened at several locations in Germany and Switzerland. More than 75 % of the accessions tested failed under the humid conditions of the first year because they did not set seed. During 2004 and 2005, seed yield per row and oil content from 486 tested accessions varied between 0 and 428 g and between 0 and 21 %, respectively. Twenty selected accessions showed seed yields between 1.4 and 2.1 t ha-1 and oil contents ranging between 21 and 23 %. Although yield potential of given accessions was strongly dependent upon climatic factors, well adapted safflower accessions for more humid conditions were identified. For future research there are several agronomic challenges to be solved for cultivating safflower in organic farming systems, such as increasing oil content and optimizing weed and disease control.
Safflower (Carthamus tinctorius L.), a member of the family of the Asteraceae, is one of the oldest cultivated crops. It often is grown on a small scale for personal use and thus remains a minor crop, with world seed production around 800 000 t per year (Gyulai, 1996). Commercial oil production from safflower seeds has been conducted for about 50 years, first for the paint industry and now mainly for its edible oil (Li and Mündel, 1996). Safflower is grown in more than 60 countries, but mainly in India, USA, Mexico, Ethiopia, Argentina and Australia (Li and Mündel, 1996). Safflower has very valuable oil for human nutrition, because of high contents of polyunsaturated fatty acids, especially linoleic acid (Honermeier, 2006). Apart from the use as an edible oil, safflower is a crop for multiple purposes. Dyes extracted from florets can be used as natural food colours or to tint natural cosmetics. Florets as well as seeds are used for cosmetic products and medicinal purposes in traditional Chinese medicine. Seeds are also used as birdseed (Li and Mündel 1996). Although, safflower can be grown across a wide range of latitudes (from 60°N to 45°S) and its product has many uses, cultivation in Germany currently is negligible (Honermeier, 2006). Because of its applicability in the human health sector as well as its usability for natural cosmetics and natural medical products, safflower seems to be a very favourable crop for organic plant production in Central Europe. However, there currently is a lack of knowledge on potential genotypes suitable to be grown under temperate climatic conditions, as well as on agronomic factors to optimize seed yield and oil content and to control weeds and pests. The aim of this study was to search for genotypes adapted to temperate climatic conditions within a great number of accessions from all over the world. A methodical approach is given on the ideotyping already done and the prototyping intended for prospective research.
Materials and methods
n 2002, 741 safflower accessions, obtained from different gene banks, breeders and official institutions from all over the world, were evaluated at the two locations Ihinger Hof (SW Germany) and Göttingen (Central Germany). The field trials were set up in a randomized block design with two replicates. Because of the limited number of seeds, safflower accessions were sown in microplots of one row of 1.2 m length. Row distance between different accessions was 40 cm. From the tested pool, 65 accessions were selected according to an index summarizing disease resistance, seed set, seed yield, etc. These selected accessions were cultivated in 2003 at three locations, Kleinhohenheim, Göttingen and Klettgau (SW Germany), on plots 1.8x3.0 m. In 2004 and 2005, 20 selected accessions were evaluated at four sites in SW Germany and Switzerland in a lattice design with four replicates. Fifty seeds per m-² were drilled in rows with a row spacing of 20-40 cm. Crop management in all trials was done according to organic standards. Weeding was done mechanically at the rosette stage, and if necessary, manually. No fertilizer was applied. Twenty agromorphological traits were evaluated. Oil content in per cent was estimated using near infrared reflectance spectroscopy (NIRS). In parallel, 468 accessions from 49 countries across 15 geographical regions were evaluated at the location Kleinhohenheim across two seasons. In a simple lattice design with two replicates, 25 seeds from each accession were drilled in a 1.2-m-long row with 75 cm inter-row distance. Statistical analyses were performed with PLABSTAT (Utz, 2002). An overview of the selection process is given in Fig. 1.
Fig. 1: Methodology of searching for safflower genotypes adapted to temperate climates (Ideotyping according to Reinbrecht et al. 2005, Elfadl et al. 2008a,b).
Results and discussion
Although highly significant genotypic effects for all evaluated parameters could be observed in 2002, about 75 % of the tested accessions failed because of high disease attack and thus no seed set (not shown). Most accessions showing satisfying values originated from Europe, especially Central Europe. Figure 2 depicts in a simplified way the broad ranges for seed yield, oil content and sensitivity to head rot infestation of the 468 accessions tested in 2004 and 2005. About 5 % of the evaluated accessions had a mean oil content ranging between 20-25 %, and about 8 % showed a low sensitivity to head rot infestation between 10 and 20 %.
ig. 2: Ranges in seed yield, oil content and head rot infestation of 468 safflower accessions grown in 2004 and 2005 at Kleinhohenheim (means across years and locations). Each dot represents one accession. Simplified illustration according to data of Elfadl et al. (2008a).
Figure 3 shows the average ranges in seed yield, oil content and head rot infestation of the 20 selected accessions evaluated across two growing seasons (2004 and 2005) and four locations. Thirteen of the 20 selected accessions showed average seed yields ranging from 1.7 to 2.0 t ha-1, with five between 2.0 and 2.2 t ha-1. Oil content showed a lower variability, ranging between 21 and 23 %. Head rot infestation ranged between 13 and 28 %. Although the evaluated parameters depended on climatic factors, well-adapted safflower accessions could be identified for more humid conditions that showed satisfactory yield and oil content and low susceptibility to head rot disease. Since cultivation of the two main oil crops in Central Europe, oilseed rape and sunflower, entails several problems under organic farming conditions, such as strong attack by insects, the high demand for nitrogen, and the high susceptibility to fungal diseases, safflower is considered to be a valuable alternative oil crop for organic farming systems under temperate climate conditions.
ig. 3: Ranges in seed yield, oil content and head rot infestation of 20 selected safflower accessions tested in 2004 and 2005 at four locations (means across years and locations). Each dot represents one accession. Simplified illustration according to data of Elfadl et al. (2008b).
The studies showed that although weather during the particular growing year had an evident impact on seed yield and oil content, safflower genotypes suitable for organic farming systems in temperate climates could be identified. However, there are still agronomic challenges to be solved, such as weed and disease control, to ensure a successful implementation in organic cropping systems. Additionally, breeding should be encouraged to increase the oil content of safflower to make it competitive with other oilseed crops.
Elfadl, E., Reinbrecht, C., Claupein, W. (2008a): Agromorphological variability in worldwide safflower (Carthamus tinctorius L.) germplasm screened for organic farming in Central Europe. Genet. Res. Crop Evol. (to be submitted).
Elfadl, E., Reinbrecht, C., Frick, C., von Witzke-Ehbrecht, S., Claupein, W. (2008b): Safflower (Carthamus tinctorius L.) as an alternative oil crop in organic farming system: Potentiality, adaptability and stability in Central Europe. J. Agric. Sci. (to be submitted).
Gyulai, J. (1996): Market outlook for safflower. In: Mündel, H. H., Braun, J., Daniels, C. (eds.): Proceedings of North American Safflower Conference, Great Falls , Montana, January 17-18, Lethbridge, AB, Canada.
Honermeier, B., (2006): Saflor. In: Heyland, K-U., Hanus, H., Keller, E.R. (eds.). Handbuch des Pflanzenbaues 4. Ölfrüchte, Faserpflanzen, Arzneipflanzen und Sonderkulturen. Verlag Eugen Ulmer, Stuttgart, 246 p.
Li, D., Mündel, H. H, (1996). In: Li Dajue, Mündel, H. H (eds). Promoting the conservation and use of underutilized and neglected crop 7: Safflower (Carthamus tinctorius). Institute of plant genetics and crop plant research, Gatersleben/International Plant Genetic Resources Institute, Rome, Italy, 8 p.
Reinbrecht, C., Barth, S., von Witzke-Ehbrecht, S., Frick, C., Elfadl, E., Kahnt, G., Becker, H.C., Claupein, W. (2005). Screening of a worldwide safflower collection für adaptation to humid temperate climates and cultivation in organic farming. In: Esendal, E. (ed.). Proceedings of the 6th international safflower conference, Istanbul, Turkey, June 06-10-2005, pp. 236-242.
Utz, H. F. (2002): A computer program for the statistical analysis of plant breeding experiments. Version 2N. Institute of plant breeding, seed science and population genetics, University of Hohenheim.