Spelt cultivation spread so widely, particularly in the Alemannic-speaking region, that this area can be considered the heartland of "Alemannic grain" (ZELLER, 1987). As late as 1913, over 231,000 hectares of spelt wheat were cultivated in Germany (HÖSEL, 1989); by the end of the 1930s, the area under spelt cultivation had declined in favor of common wheat, Triticum aestivum (WINZELER and RÜEGGER, 1991). In Switzerland, too, spelt was the most important bread grain, as evidenced by the term "Korn" (grain) used for spelt. The main bread grain was referred to as "Korn" in every country. Spelt also held a prominent position in western Austria for many centuries. Precisely because of its undemanding nature with regard to climate and soil, spelt could be cultivated in the Alpine regions and was only replaced at the beginning of the 20th century by significantly higher-yielding common wheat varieties. This was certainly also due to the fact that processing spelt requires several steps compared to wheat, which definitely includes dehusking, i.e., removing the husks.
In the wake of a general increase in health awareness, spelt was rediscovered around 25 years ago. Following the motto "Back to nature," ancient cultivated plants experienced a renaissance, as did a renewed interest in traditional remedies and recipes. As early as the 12th century, Hildegard von Bingen had described spelt as a medicinal plant with excellent properties and achieved successful treatments with it. This plant gained new prominence at the end of the 20th century. Much was also expected of spelt in terms of its nutritional content, and many of the original claims have since been scientifically proven. For example, Jacquot et al. (1960) demonstrated significantly higher protein content in spelt compared to common wheat, on the same order of magnitude as durum wheat, while Clamot (1984) found virtually no difference between these two Triticum species. Seibel (1989) also classifies spelt's protein content as similar to durum wheat. Furthermore, he classifies foods made from spelt in the category of "healthy food." ZÜLLIG (1984) compares various selected constituents of spelt and wheat (investigations of the whole grain), whereby the results of the individual values differ considerably; however, the overall nutritional content of the substances is above average. Similarly, there are studies on the mineral content of various spelt varieties compared to common wheat (MOUDRY and DVORACEK, 1999). Here, only a statistically significant difference could be found for zinc, although the analytical results, with the exception of calcium, consistently showed higher levels in spelt. The selenium content, in particular, is said to be higher in spelt than in wheat and therefore of special importance for human nutrition. JOHNSSON (1991) investigated the selenium content in Triticum sativum over a long period, which unfortunately did not include hulled wheat. This chemical element plays an important role in human nutrition.
Selenium in Spelt
W. Hein*, A. Edelbauer and H. Grausgruber**
Introduction
Spelt (Triticum spelta) is an ancient cultivated plant that—as the name suggests—is related to wheat. In Southwest Asia, spelt was already cultivated and used around 6000 BC. Over the centuries, spelt also spread to Europe, where it became widespread, particularly in Central and Northern Europe, especially from Roman times onward. Spelt cultivation spread so rapidly in the Alemannic-speaking region that this area can be considered the heartland of "Alemannic grain" (ZELLER, 1987). As recently as 1913, over 231,000 hectares of spelt were cultivated in Germany (HÖSEL, 1989); Until the end of the 1930s, the area under spelt cultivation declined in favor of common wheat, Triticum aestivum (WINZELER and RÜEGGER, 1991). In Switzerland, too, spelt was the most important bread grain, as evidenced by the term "Korn" (grain) used for spelt. The main bread grain was referred to as "Korn" in every country. Spelt also held a prominent position in western Austria for many centuries. Precisely because of its undemanding nature regarding climate and soil, spelt could be cultivated in the Alpine regions and was only replaced at the beginning of the 20th century by significantly higher-yielding common wheat varieties. The fact that processing spelt requires several steps compared to wheat, including dehusking (removing the husks), certainly contributed to this decline.
Significance of Selenium as a Trace
Element: As a chemical element, it belongs to group 16 of the periodic table with the natural isotopes (abundance in parentheses) 74 (0.9%), 76 (9.0%), 77 (7.6%), 78
(23.6%), 80 (49.7%), and 82 (9.2%); its atomic weight is 78.96 and its atomic number is 34. Selenium is located directly below sulfur in the periodic table and, like sulfur, occurs in the oxidation states -2, +2, +4, and +6; compounds with tetravalent selenium are the most common and stable. Selenium, like its homologous sulfur, exists in several allotropic modifications (Römpp, 1990).
Selenium is a structural component of the enzyme glutathione peroxidase. Glutathione peroxidase plays an important role in the body's antioxidant defense mechanisms and is found particularly abundantly in certain cells such as erythrocytes, phagocytes, and platelets, as well as in the liver, eyes, and all organs and tissues with a particularly active oxidative metabolism. Selenium is significantly involved in thyroid hormone metabolism (Mayer, 1998). Selenium is an important cell-protective factor, thus offering protection against chromosomal damage and increasing the body's resistance to pathogens. Selenium is essential for maintaining all bodily functions. Selenium also protects against the acceleration of aging processes and damage to the genetic material.
The World Health Organization (WHO) states that the optimal daily intake of selenium for an adult is 50–200 µg. However, the German Nutrition Society (DGE) recommends only an amount between 20 and 100 µg per day, taking into account age, sex, general health status, and any potential risk groups. The average selenium intake in Germany is only around 40–60 µg/day, which is borderline deficient. In certain diseases such as heart attack, coronary artery disease, cancer, or liver cirrhosis, selenium levels in whole blood or serum have been found to be far below normal. Severe selenium deficiency in humans leads to pathological enlargement of the heart and severe joint diseases (Keshan disease).
The main sources of selenium in the human diet are animal and plant proteins. Approximately 65% of total selenium intake comes from animal proteins, with seafood, eggs, chicken, and pork being particularly rich in selenium (Mayer, 1998). Among plant-based foods, selenium comes primarily from grains, but soybeans, sesame seeds, sunflower seeds, nuts, asparagus, and garlic are also higher in selenium than other fruits and vegetables. However, the selenium content of grains depends heavily on the selenium content of the soil, which in the USA and Canada is about ten times higher than in Europe. The selenium content of European soils ranges from 0.194 mg/kg in Schleswig-Holstein to 0.074 mg/kg in Bavaria. Similar data exists for Austria, with values around 0.2 mg/kg (Aichberger and Hofer, 1989; BZI, 1994). A range between 0.6 and 4 mg/kg is considered optimal. Therefore, the selenium content of North American grains is also significantly higher than that of European grains, although regional variations exist. North American wheat can contain several mg/kg of selenium, 10 to 20 times more than is found in Central European wheat grains. Thus, the selenium content of European grains is insufficient to meet daily selenium requirements. However, the selenium content of cereal grains could be increased through specific fertilization, as has already been done in Finland. Investigations by Horak and Liegenfeld (1996) showed selenium levels in Austrian cereal grains between 1 and 64 µg/kg. Hösch (2002) presented results on the effect of selenium fertilization on cereal grains. It was demonstrated that selenium fertilization increased the content in the grains in both pot and field trials.
Materials and Methods:
Field Trials.
Based on investigations of the selenium content of various spelt varieties from a field trial conducted in 1999/2000 at both the main experimental field in Gumpenstein and the field station in Kobenz, a field trial specifically on selenium fertilization was established in Gumpenstein in autumn 2000. While the two field trials in 1999/2000 focused on comparing different spelt varieties, only three spelt varieties and one soft wheat variety were selected for the 2000/2001 field trial. To largely eliminate the influence of the year, the same trial was repeated the following year. The trials were designed as block plots with four replicates.
site
is characterized by the following parameters: the altitude is 710 m, the average annual temperature is 7.6°C, and the annual precipitation is 1010 mm. A continuous snow cover can last for over 100 days, although this has not been achieved in recent winters. The soil type is a loose, brown earth with a pH of 5.8 and 3.9% humus. The soil composition is 30% sand, 63% silt, and 7% clay; the soil is therefore permeable and easy to work.
Fertilization
: The following fertilizers were used for nutrient supply in 2001 and 2002: For the 2000/2001 trial, the main nutrients were applied in the form of a multi-nutrient fertilizer with a ratio of 20:8:8:3; in addition, variants with and without selenium were used. This resulted in the following at 375 kg/ha: 75 kg/ha nitrogen, 30 kg/ha P₂O₅, 30 kg/ha K₂O, and 11 kg/ha MgO. Superphosphate and 40% potassium salt were also applied as supplements. A top dressing of selenium was applied to one-third of the plots. In the 2001/2002 trial, a base dressing of superphosphate and 40% potassium salt was applied in the autumn before planting, followed by nitrogen fertilization with Nitramoncal in the spring at the same rate as the previous year. In 2001, the selenium was applied as sodium selenate. The first application was with the multi-nutrient fertilizer, the second application (only in selenium level 2) was as a foliar spray. In 2002, selenium was applied exclusively via foliar spray.
The selenium levels were as follows: Se0: without selenium
; Se1: with 6 g/Se/ha
; Se2: with 12 g/Se/ha
Varieties:
When selecting varieties, an attempt was made to use those widely used in practice. These certainly include the spelt varieties Ostro and Schwabenkorn, which were cultivated in both years. The former is a Swiss variety, and the latter a variety from southern Germany. The third spelt variety in the 2000/2001 trial was Ebners Rotkorn, an Austrian selection; however, the variety ÖKO 10, which was cultivated as the third variety in the 2001/2002 trial year, is a Hungarian breeding. The soft wheat variety Capo, a quality wheat that also produces good yields in damp and transitional locations, was used as the comparison variety in both years.
Other trial conditions
Potatoes were grown as a preceding crop in both trial years.
The seeding rate was 350 seeds/m², which corresponds to approximately 240 kg/ha for spelt. However, the current germination rate and thousand-grain weight were taken into account in the calculation.
A harrow was used for weed control in early spring.
Sowing took place in autumn 2000 on October 23rd, relatively late for a plot in the inner Alpine region. Nevertheless, emergence of the plants could still be observed in late autumn, although they entered winter at the 1-2 leaf stage.
The following year, the trial could be sown as early as mid-October, specifically on October 15th. Even then, emergence of the plants was observed approximately three weeks later.
Harvesting took place in mid-August each year: on August 13th in 2001 under favorable conditions, and on August 16th in 2002, the earliest possible day after torrential rains.
Chemical Analysis
The finely ground (Sampling
In the first year of the trial, flag leaves were initially taken at the beginning of July. At harvest, samples were taken from both the grain and the straw. In the following year, only samples of grain, straw, and husks were submitted for analysis at harvest.
Results
One of the most important results for cereals is undoubtedly the grain yield. Since the husked grains are harvested during threshing in spelt, this is the grain yield. A further processing step, called dehusking, which is carried out with special machines, results in the actual bare grain. The yield of this is called the "kernel yield" in spelt and is then comparable to the grain yield of common wheat.
When considering the yields, the significantly higher yield level of 2001 compared to 2002 is immediately noticeable. This is evident in both spelt and common wheat yields. The lower yields in the second year of the trial were due to the rather exceptional weather conditions: very high temperatures in spring and Unusually heavy rainfall in the summer meant that the distribution of precipitation was not favorable for grain formation.
Yields:
The grain and kernel yields from 2001 are shown in Figure 1, where the different terms refer to spelt.
The yields in the individual selenium levels are quite similar; however, no effect on grain yield was expected from selenium fertilization. Within the spelt varieties, each variant has a different ranking.
The yield of the soft wheat variety Capo is interesting in this context, as it corresponds exactly to the grain yield of the spelt varieties. Reducing this by the husk content yields the kernel yield. Depending on the variety, moisture content, and thus the ripeness of the grains, approximately 30–40% of the original yield consists of husks. The husk content also varies considerably; the range extends from 31.9% at selenium level 0 for the variety Ebners Rotkorn to 41.7% at selenium level 1 for the variety Schwabenkorn.
Figure 2 shows the yields from 2002. It is noticeable that not a single value even comes close to the yields of the previous year. Not even the grain yields of spelt from 2002 come close to the kernel yields of 2001. This year, the Capo variety still yields more than 500 kg/ha higher than the grain yields of the spelt varieties. Looking at the dehulled grains, the highest value is found in the Schwabenkorn variety in selenium level 2, with almost 24 dt/ha. The husk content does not reach 30% in any variant.
Figure 3 shows the straw yield at 86% dry matter for each variety from both trial years. In 2001, the common wheat variety had a significantly lower straw yield than the long-strawed spelt varieties. The variety Schwabenkorn had the highest straw yield in all three selenium levels, exceeding 50 dt/ha. For the other two spelt varieties, no clear ranking within the selenium levels was evident.
In 2002, the straw yields were higher, as were those of the common wheat. In selenium levels 1 and 2, the straw yield of the variety Capo was the absolute highest, while in selenium level 0, the same variety had the lowest straw yield.
No effect of selenium fertilization on straw yield is expected, just as with grain yield; however, varietal differences are noticeable.
Selenium content:
The following provides information on the selenium content of the individual plant parts.
This shows that the difference between the zero selenium level and the application of 6 g/ha of selenium via the soil is significantly smaller than between selenium levels 1 and 2, where the remaining 6 g/ha of selenium was applied via foliar fertilization. The differences are highly significant for both flag leaves and grains. A varietal difference was only observed between Capo and the three spelt varieties.
The differences in the grains are far less pronounced, as shown in Figure 5. The clear result is that the selenium content of the Capo variety is lower than that of the spelt varieties in all three selenium levels. The trend suggests that foliar application is likely more effective than soil application in increasing selenium content.
The selenium removal of the variants, which include grain and straw, averaged between 103 (Se0), 562 (Se1), and 1098 (Se2) mg/ha in 2001. In the two variants fertilized with selenium, the majority of the selenium removal occurred in the grain.
Practical implications:
Since the natural selenium content of grain produced in Austria, as well as in the rest of Europe, is very low, various projects have attempted to increase the selenium content through selenium fertilization. Selenium is an essential trace element that the human body requires in amounts of approximately 50–100 µg daily. The average selenium intake in Germany is around 40–60 µg, which is borderline deficient. Selenium content in wheat produced in North America can be 10 to 20 times higher than in European wheat. If the selenium content of spelt were significantly higher than that of common wheat, new possibilities could arise for spelt.
In the project described above, the selenium differences observed in preliminary trials between spelt varieties could no longer be confirmed after targeted selenium application.
However, even small amounts of selenium (6 to 12 g/ha) in the form of sodium selenate can easily raise the selenium content of the grains to the nutritionally desirable range.
The utilization rate of selenium is rather modest; at harvest time, grains and straw together contain only about 7% of the applied selenium.
References:
AICHBERGER, K. and GF HOFER (1989): Arsenic, mercury, and selenium content of agriculturally used soils in Upper Austria. Die Bodenkultur, 40, 1-11.
BZI, 1994: Lower Austrian Soil Condition Inventory, Office of the Lower Austrian Provincial Government, Vienna.
CLAMOT, G. (1984): Genetic Variability of the Protein and Lysine Content of Spelt (Triticum spelta). Zeitschrift für Pflanzenzüchtung, 93, 106-114.
HÖSCH, J., (2002): Influence of fertilization on the selenium uptake of cereals. Report on the ALVA Annual Meeting 2002 in Klosterneuburg, 381-384.
HORAK, O. and R. LIEGENFELD (1996): Investigations on selenium transfer soil-cereal. VDLUFA - Schriftenreihe, 44, 687-690, Congress Proceedings, 1996.
HÖSEL, W. (1989): Cultivation area, utilization, production technology and economic viability of spelt cultivation in southern Germany. Bayer. landw. Jahrbuch, 60, 501-507.
JACQUOT, R.; ADRIAN, J. and A. RERAT (1960): A forgotten cereal: Spelt. Zeitschrift für Acker- und Pflanzenbau, 274-288.
JOHNSSON, L. (1991): Trends and annual fluctuations in selenium concentrations in wheat grain. Plant and Soil, 138, 67-73.
MAYER, IM (1998): Selenium and its importance for human nutrition. Verbraucherdienst, 11, 632-636.
MOUDRY, J. and V. DVORACEK (1999): Chemical composition of grain of different spelt (Triticum spelta L.) varieties. Rostlinna Vyroba, 45 (12), 533-538.
MÜLLER-WETTLAUFER, G.; SCHWEIZER, Th. and W. HAUBOLD (1989): On the selenium content of the investigated cereal. Proceedings of the 1st Spelt Colloquium, held at the University of Hohenheim on July 29, 1988, published by the Spelt Field Foundation, Volume 1, pp. 371–377.
RÖMPP (1990): Chemistry Lexicon, published by Thieme Verlag, 9th edition, Volume 5, p. 4105.
SEIBEL, W. (1989): Potential uses of spelt wheat milling products in the production of small baked goods, bread, and pasta. Proceedings of the 1st Spelt Colloquium, held at the University of Hohenheim on July 29, 1988, published by the Spelt Field Foundation, Volume 1, pp. 95–109.
WINZELER, H. and A. RÜEGGER (1991): Spelt: Renaissance of an ancient grain. Agriculture Switzerland, Volume 3 (9), pp. 503–511.
ZELLER, O. (1987): Spelt or hulled spelt, the former Swabian grain. Demeter-Blätter, 42, 3-6.
ZÜLLIG, M. (1984): Comparison of selected constituents between spelt and wheat. Research report of the Research Institute for Organic Agriculture, Bernhardsberg.
