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Variability of the parameters of technological quality in the Slovak spring barley gene pool

Variability of the parameters of technological quality in the Slovak spring barley gene pool Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 DOI: 10.2478/v10207-012-0012-9 MICHAELA BENKOVÁ*, MICHAELA HAVRLENTOVÁ, UBOMÍR MENDEL, PAVOL HAUPTVOGEL Plant Production Research Center Piesany BENKOVÁ, M. ­ HAVRLENTOVÁ, M ­ MENDEL, . ­ HAUPTVOGEL, P.: Variability of the parameters of technological quality in the Slovak spring barley gene pool. Agriculture (Ponohospodárstvo), vol. 58, 2012, no. 3, pp. 99­112. The total 43 Slovak spring barley genotypes with a year of cultivation or registration from 1938 to 2009 were evaluated in terms of selected parameters like protein, starch, and -glucan contents. Collection of genetic resources consisted of barley malting qualities such as elite ­ A, standard quality ­ B, no malting quality ­ C and five genotypes of unspecified malting quality. Significant (P < 0.01) influence of genotype and environmental conditions (years) and also genotype × year interaction on protein, starch, and -glucan content in the barley grain were detected. The highest average protein content was observed in genotypes from the group with undetermined malting quality. The protein and -glucan contents in older genotypes were higher in comparison with more recent genotypes. The average starch content in both older and modern genotypes in the studied set was nearly identical, which con- firms a high quality of the older malting varieties. According to malting quality groups, the highest average value of -glucan content was in the group of no malting quality (C) and the lowest in the group of best malting quality (A), which is in correspondence with barley malting quality requirements. In individual years differences in the -glucan content were found among genotypes. Despite the atypical years, good sources of -glucan were found out along with modern genotypes such as Cyril and older genotypes such as Orbit and Vladan, but also historically old genotypes were created in the year 1946 such as Diosecký 802 and Slovenský Dunajský trh. Our study has confirmed that these genotypes are donors of not only significant agronomic traits but also qualitative properties, usable in the food industry. Key words: barley, -glucan, starch, protein, genotype, environment Barley (Hordeum vulgare L.) is the second mostly represented crop after wheat in Slovakia. Barley covers an area of 136,300 ha (2011). Barley sowing is very important for the national economy; it is grown as a raw material for the food industry, for feeding animals, and for malt production. Currently 57 varieties of spring barley and 24 winter barley varieties are registered in Slovakia; from this 17 varieties are of Slovak origin (List of registered varieties 2011). Although growing of spring barley is connected with brewing, today a renaissance in the use of barley grain as food has been recorded, first of all in developed countries all over the world (Ehrenbergerová 2006). Here barley is used for production of so-called functional foods. Naked barley has a big role in the food industry, with beneficial nutritional and dietary uses. Its disadvantage is its yield that is lower about 15% in comparison with glumose varieties (Candráková et al. 2000). Biological and agricultural characters of the currently registered barley varieties fulfil conditions of intensive growing; they are adequately resistant to leaf diseases and have good malting quality and high grain yield (Sleziak 2003). According to the National Biodiversity Strategy of Slovakia, barley genetic resources include not only modern varieties, cultivars, and hybrids used mostly in agriculture but also drawn varieties, old landraces, Ing. Michaela Benková, PhD., RNDr. Michaela Havrlentová, PhD., Ing. ubomír Mendel, PhD., Ing. Pavol Hauptvogel, PhD., Plant Production Research Center, Bratislavská cesta 122, 921 68 Piesany, Slovak Republic. E-mail: benkova@vurv.sk (*Corresponding author) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 ecotypes from widespread plant species. and their natural populations. These so-called historical genetic resources have been used as a store of rare genes. Because the long-time selection of barley was constantly influenced by human needs in terms of nutrition and quality of barley, it causes permanent loss of valuable sources of variability in the germplasm. Typically, many modern varieties of spring barley have relatively narrow genetic basis, and to a certain extent they are similar (Kraic et al. 2004; Psota 2009). Quality of barley grain is a complex character, which is subject to complex genetic conditions, considerably affected by agro-ecological growing conditions and depending on the genotype-environment interaction. Barley grain contains 80­88% of solids and 12­20% of water. The dry matter is composed of nitrogen and nitrogen-free organic compounds and inorganic substances (Sleziak 2003). To carbohydrate components belong starch and non-starch polysaccharides (cellulose, hemicellulose, rubber substances, and lignin). Starch content (%) is decisive for extract formation, and therefore it is a significant parameter of barley quality. In malting barley, starch content in dry matter moves around 63­65%, and it should not be lower than 60% (Prugar & Hraska 1989). Starch content depends not only on protein amount but also on the state of growth and sunshine period during the final phases of vegetation. There is a negative correlation between the content of starch and protein in barley grain (Sleziak 2003). The most important components of hemicelluloses and gummy substances are in the barley grain -glucans. From the chemical point of view, -glucan ([1-3][1-4]--D-glucan) consists of glucose units connected by -(1-3)- and -(1-4)- glycosidic bonds in variable proportions, most frequently in the ratio 30 : 70. Grains of barley contain the highest amount of -glucan among all cultivated cereals (Henry et al. 1985). The average -glucan content in barley grains is 7.5% in high amylose, 6.9% in waxy, 6.3% in zero amylose waxy, and 4.4% in normal starch types (Baik et al. 2008). The amount and composition of hemicelluloses and gummy substances and particularly in them containing -glucans and pentosans depends on growing conditions. Short growing season, high temperatures, and drought during growth increase not only the protein content but also the content of non-starch polysaccharide. The effect of genotype is also signifi100 cant (Prugar & Hraska 1989). According to Rey et al. (2009), 66% of variability in the content of -glucan can be attributed to the genotype. A low -glucan and protein content and contrarily higher content of starch in the grain are desirable for malting barley. -glucans fulfill the function of building materials in the endosperm cell walls in contrast to starch, which serve as a storage substance. -glucans stop the entry of enzymes into cells, thus negatively affecting the speed of deciphering of the grain during malting. On the other hand, higher -glucan content is the most important attribute for barley varieties destined for the human food market (Rey et al. 2009). In terms of functional foods, barley -glucans have a great importance as a health-enhancing ingredient (Huth et al. 2000). This component significantly supports the immune system, effectively prevents cardiovascular diseases, and protects from excessive physical or mental stress. It also serves as a antibiotic and assists in chemotherapy and radiotherapy (Charalampopoulos et al. 2002). Based on the assessment of technological quality of selected parameters such as -glucan, protein, and starch content in the barley grain, the aim of our work was to identify the potential of historical, later-created, and new Slovak varieties usable for human nutrition and consumption. MATERIAL AND METHODS Samples of spring barley grains in 43 genotypes of the Slovak origin within a year of cultivation or registration from 1938 to 2009 were obtained from the Gene Bank SR in PPRC Piesany (Table 1). Samples were consequently multiplied and evaluated in the field small-plot trials with the harvest area of 2.5 m2, on the experimental basis in Piesany for two years 2010 and 2011. This experiment was arranged in a randomized block design with two replications. The obtained samples were analyzed for selected parameters of technological quality: -glucans content [%], protein content [%], and starch content [%]. The data obtained have been converted to 100% dry weight basis. Collection of genetic resources consisted of barley malting quality as elite ­ A (13 genotypes), standard quality ­ B (12 genotypes), non-malting quality ­ C (13 genotypes) and five genotypes of unspecified malting quality ­ U (5). Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 T a b l e 1 Characteristics of Slovak spring barley genotypes set released from years 1938­2009 Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 Genotype Diosecký Kneifel Terrasol pivovarský Diosecký 802 Diosecký Sprinter Nitriansky Export Slovenský Dunajský trh Slovenský jemný Slovenský kvalitný Pudmerický pivovar Buciansky Kneifel Vigasský polojemný Dvoran Sladar Fatran Horal Orbit Novum Galan Jubilant Sladko Svit Donum Stabil Garant Kosan Zlatan Amos Kompakt Vladan Progres Expres Cyril Ludan Nitran Ezer Pribina Argument Nadir Poprad Slaven Levan Donaris Sladar new Year of release 1938 1944 1946 1946 1946 1946 1946 1946 1948 1955 1958 1965 1967 1980 1982 1986 1988 1990 1991 1992 1992 1993 1993 1994 1994 1994 1995 1995 1996 1998 1999 2000 2002 2003 2004 2005 2006 2006 2006 2007 2008 2009 2009 Malting quality type unspecified unspecified A unspecified B A A A unspecified B unspecified B A B C B B B A A C C C B C C C A B C A C B A B C C B C C A A A Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 After growing, the grains were dried and milled to pass a 0.5 mm screen using Ultracentrifugal Mill (ZM 100, Retsch GmbH & Co. KG, Haan/Germany). Before each analysis they were stored in hermetic boxes under temperatures of 5°C. Nitrogen content was determined by the Dumas method on the CNS-2000 (Leco Corp., US), and the coefficient 6.25 was applied for recalculation. Starch content was determined by the Ewers polarimetric method (STN 461011-37), and optical activity was recalculated to starch concentration by the coefficient for barley 5.5096. -glucan level was determined using Mixed-linkage eta-glucan assay procedure (Megazyme, Ireland) (McCleary 2011). This method is accepted by the AOAC (Method 995.16) and the AACC (Method 32-23). Samples were suspended and dissolved in a 0.02 M sodium phosphate buffer (pH 6.5), incubated with purified lichenase enzyme, and an aliquot of filtrate was reacted with purified -glucosidase enzyme. The glucose product was assayed using an oxidase/peroxidase reagent recalculated to -glucan content. Analysis of data was performed using statistical software (Statistica 8.0, Statsoft, Inc. 2008) with analysis of variance (ANOVA) and Pearson's correlation coefficient. Differences were considered significant at P < 0.05, unless otherwise specified. Experimental fields were situated in the maize production area, a subtype maize-wheat. Altitude is 162 m; soil is Luvic chernozem (World Reference Base for Soil Resources 2006). The humus horizon is around 40­50 cm deep. Soil reaction of top layers is neutral, and it becomes moderately alkaline in deeper layers. Long-term normal precipitation is 595 mm, with an average annual temperature of 9.2°C (years 1961­1990). Course of vegetation Average temperatures during the vegetation of barley in 2010 and 2011 corresponded to the long-term normal. In 2010 during sprouting there was half the amount of precipitation in comparison to the longterm normal. Therefore, the crop was less involved. During the beginning of the heading period the amount of rainfall was three times heavier when compared to the long-term average. Supernormal rainfall extended the heading period for many varieties of barley and caused a high occurrence of diseases, especially powdery mildew. In 2011, during sprouting precipitation was on an equal level with that of the long-term average. Gradually the precipitation was added at the time of heading and milk ripeness and exceeded the long-term average of more than 40%. There was sufficient rainfall to ensure a rapid increase in leaf area, although it did not Month Precipitations [mm] Temperature [°C] Month Figure 1. Mean monthly temperatures (a) and total monthly precipitation (b) for the years 2010 and 2011 compared to normal (50 years) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 cause the occurrence of diseases, as in 2010, which was reflected in improved grain yield. The detailed course of weather in years 2010 and 2011 is given in the Figure 1. by our results (Figure 2). In the year 2010, intensive rainfall during heading and grain production decreased quality of the malting barley, and protein content was highly increased. The average protein content was statistically different in genotypes from the group with undetermined malting quality (12.89%) (Table 4). The average protein content of genotypes from the group of good malting quality (A) was 11.53% and lowest content was in genotypes of non-malting quality (C), 11.23%. These results were affected by extreme humidity during vegetation in the year 2010. In the whole experiment, the value of protein content fluctuated from 8.76% (Jubilant) to 14.85% (Buciansky Kneifel) (Figure 2). Some genotypes responded very sensitively to the humidity in 2010. For example we recorded the average protein content in Nitran, a malting variety, to be over 14.0%. During the two years we recorded high average protein content at malting quality genotypes of type B (Buciansky Kneifel ­ 14.34%) and similarly high protein content was recorded in genotypes with undetermined malting quality like in Diosecký Kneifel ­ 13.72% and Terrasol pivovarský ­ 14.4% (Table 5). We found out that protein content in older genotypes was higher in comparison with more recent genotypes. On the other hand, contents of starch and -glucan were higher during the 2011 vegetation period (Figures 3, 4). Starch content is decisive for the extract formation, and therefore it is a significant parameter of barley quality. In malting barley, starch content in dry matter moves around 63­65%, and it should not be lower than RESULTS AND DISCUSSION It was important to determine the factors affecting the analyzed traits while assessing a total of 43 Slovak spring barley genotypes in terms of selected characteristics. The ANOVA (Table 2) detected significant (P < 0.01) influence of genotype and environmental conditions (years) on protein, starch, and -glucan content in the barley grain. Genotype × year interaction had a statistically significant effect (P < 0.01) on all monitored characters, too. Protein content is generally considered as the most important parameter of the processing value of malting barley. It can vary within a very wide range (7­18% in dry matter). Good quality malting barleys should have protein content within 10.00­11.5% (Kosa et al. 2000). The average protein content in the monitored genotypes was higher in the year 2010 (12.36%) in contrast to year 2011, when it was only 10.98% (Table 3). The mean value per two years was 11.67%. The distribution of rainfall for barley cultivation is very important. Humidity is needed especially during the stems and grains production, but intensive rainfall increases the nitrogen content (Sleziak 2003), which resulted in higher protein content in the grain. This observation is confirmed T a b l e 2 Analysis of variance of protein, starch and -glucan contents in 43 spring barley genotypes Protein [%] SS 236.78 77.55 82.79 0.47 397.59 MS 5.64 77.55 1.97 0.01 F 1030.5 360.3 Source of variation Genotyp Year Genotyp × Year Residual Total df 42 1 42 86 171 Starch [%] SS 773.90 160.10 327.30 3.50 1264.74 MS 18.40 160.10 7.80 0.01 F 455.0 193.0 ß-glucan [%] SS 24.41 7.91 14.11 1.31 47.73 MS 0.58 7.91 0.34 0.02 F 38.2 520.4 22.1 14174.9 3956.0 significant at 0.01 probability level Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 60% (Prugar & Hraska 1989). Higher starch content affects extract content directly. When there is a lack of starch in the grain, it is not possible to increase the percentage of extract by any other technology. Starch amount depends not only on protein content but also on the state of growth and sunshine period during the final phases of vegetation (Sleziak 2003). Genotypes and experimental years affected variability of the starch content significantly (Table 2). Atypical humid years influenced the content of starch in barley grain, when the average value of starch content in 2010 was only 53.89% and in 2011 it was 55.82% (Table 3). Higher rainfall during grain produce and the ripening period reduced the malting quality. The aver- T a b l e 3 Basic statistical characteristics of qualitatively parameters of barley genotypes in two analyzed years Characteristics Protein [%] Years 2010 2011 Total 2010 Starch [%] 2011 Total 2010 ß-Glucan [%] 2011 Total x 12.36a 10.98b 11.67 53.89 SD 1.27 1.49 1.54 2.59 2.51 2.72 0.50 0.47 0.53 v [%] 10.24 13.58 13.19 4.81 4.49 4.96 12.53 10.51 12.53 Min. 8.81 8.76 8.76 46.12 50.04 46.12 2.88 3.50 2.88 Max. 14.67 14.85 14.85 58.71 60.47 60.47 5.03 5.93 5.93 55.82b 54.85 4.00a 4.43 Values in the same column with different letters are significantly different (P < 0.05). SD - Standard deviation T a b l e 4 Average value of protein, starch and -glucan contents within individual groups of barley genotypes Characteristics Malting quality type A Protein [%] B C U A Starch [%] B C U A ß-Glucan [%] B C U x 11.53 SE 0.18 0.19 0.18 0.29 0.33 0.34 0.33 0.53 0.07 0.07 0.07 0.11 Confidence limits for mean -95% 11.17 11.44 10.88 12.32 54.53 54.29 54.82 51.07 3.98 4.10 4.15 4.04 +95% 11.89 12.18 11.59 13.47 55.83 55.64 56.12 53.16 4.25 4.38 4.42 4.47 11.81a 11.23a 12.89b 55.18a 54.97 52.11 55.47a 4.12a 4.24 4.25 4.28a A - malting quality elite C - no malting quality SE - Standard error B - standard malting quality U - undetermined malting quality Values in the same column with different letters are significantly different (P < 0.05) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 T a b l e 5 Variations in average protein content in barley genotypes of malting quality types in two years Confidence limits for mean ­95% 12.14 10.19 11.47 8.87 11.10 11.52 13.99 11.34 10.66 11.06 11.87 11.99 12.73 11.17 14.27 10.87 9.52 10.39 10.21 11.88 11.40 12.63 12.75 12.88 11.62 12.43 11.44 12.05 11.52 10.28 9.84 11.37 10.62 11.58 10.86 11.01 12.04 11.99 10.76 11.16 10.88 13.64 11.19 12.36 12.94 13.97 12.32 +95% 12.29 10.34 11.62 9.01 11.25 11.67 14.14 11.48 10.81 11.21 12.02 12.14 12.88 11.89 14.42 11.02 9.67 10.54 10.36 12.03 11.54 12.77 12.90 13.03 11.77 12.58 12.18 12.19 11.67 10.43 9.99 11.51 10.77 11.72 11.01 11.15 12.19 12.14 10.91 11.31 11.59 13.79 11.34 12.51 13.09 14.12 13.47 Malting quality groups/Genotype Group A Diosecký 802 Donaris Expres Jubilant Kompakt Levan Nitran Sladar Sladar-new Sladko Slovenský kvalitný Slovenský Dunajský trh Slovenský jemný Average (n=13)** Group B Buciansky Kneifel Dvoran Ezer Fatran Galan Garant Ludan Nadir Nitriansky Export Novum Orbit Vladan Average (n=12)** Group C Amos Argument Cyril Donum Horal Kosan Poprad Pribina Progres Slaven Stabil Svit Zlatan Average (n=13)** Group undetermined Diosecký Kneifel Diosecký Sprinter Pudmerický pivovar Vigasský polojemný Terrasol pivovarský Average (n=5)* Protein [%]* 12.22o 10.27d 11.55klm 8.94a 11.17h 11.60klm 14.06u 11.41ijk 10.73ef 11.13gh 11.95n 12.07no 12.80rs 11.53a 14.34v 10.94fg 9.60b 10.46d 10.29d 11.96n 11.47jkl 12.70qr 12.83rs 12.95s 11.70m 12.50pq 11.81a 12.12no 11.59klm 10.36d 9.92c 11.44ijkl 10.69e 11.65lm 10.94fg 11.08gh 12.11no 12.07no 10.84ef 11.24hi 11.23a 13.72t 11.27hij 12.43p 13.02s 14.04u 12.89b *Values in the same column with different letters are significantly different (P < 0.05) **Average of each malting quality groups. Values in the same column with different letters are significantly different (P < 0.05) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 age starch content was lower in all groups (Table 4) and hardly reached 60% in any genotype, even in the high quality malting varieties (Jubilant, Expres, Nitran). The highest content of starch was determined in the 2011 vegetation period in genotypes Ezer (60.47%) and Galan (59.90%) from the group of malting quality B (Figure 3, Table 3). The average value of starch content during years 2010 and 2011 (Table 6) ranged from 48.26% (Terrasol pivovarský) to 58.86% (Ezer), which is a very low content. Average starch content in older and modern genotypes in the studied set was nearly identical, which confirms a high quality of older malting varieties in spite of the fact that the breeding aims during the last 10 years have been focused on improving malting quality and thus also increasing starch content. Similar to starch also the -glucan content (Figure 4, Table 3) was higher in 2011 (4.43%) compared to 2010 (4.00%). Differences between years and cultivars (Table 2) and interaction of this combination were statistically significant (P < 0.01). In the literature, water stress has been found either to reduce (Macnicol et al. 1993) or to increase (Savin et al. 1996) the -glucan content. According to Zhang et al. (2001), wet days, associated with lower temperatures, were positively correlated with -glucan content. The -glucan is deposited in walls of the endosperm cells during the later stages of grain filling. Thus conditions favorable to endosperm development would increase the accumulation of -glucan in the grain. High precipitation is unfavorable for endosperm development, and high temperatures may shorten the duration of grain filling. Relatively less -glucan will be synthesized and accumulated on the walls of the endosperm cells in comparison with total dry matter, mainly starch and protein, leading on the other hand to lower -glucan content. It can be assumed that similarly in our case the high rainfall in the month of May (Figure 1) in 2010 (164 mm) during the formation of grain caused reduction of -glucan in barley genotypes. Low -glucan and protein content are desirable qualities for malting barley. According to the malting Figure 2. Variability of protein content in barley genotypes in two analyzed years Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 T a b l e 6 Variations in average starch content in barley genotypes of malting quality types in two years Malting quality groups/Genotype Group A Diosecký 802 Donaris Expres Jubilant Kompakt Levan Nitran Sladar Sladar-new Sladko Slovenský kvalitný Slovenský Dunajský trh Slovenský jemný Average (n=13)** Group B Buciansky Kneifel Dvoran Ezer Fatran Galan Garant Ludan Nadir Nitriansky Export Novum Orbit Vladan Average (n=12)** Group C Amos Argument Cyril Donum Horal Kosan Poprad Pribina Progres Slaven Stabil Svit Zlatan Average (n=13)** Group undetermined Diosecký Kneifel Diosecký Sprinter Pudmerický pivovar Vigasský polojemný Terrasol pivovarský Average (n=5)** Starch [%]* 55.26lmn 57.60tu 53.75gh 58.01u 55.52mnop 56.33rs 57.24t 55.86opqr 55.37lmno 55.13klm 52.79de 51.93c 52.52d 55.18a 51.19b 56.14qrs 58.86v 55.72nopq 58.08u 53.49fg 56.03pqrs 55.96pqr 53.60g 52.68d 54.94jkl 52.91de 54.97a 56.40rs 56.59s 55.55mnop 57.33t 55.05jklm 56.37rs 54.25hi 56.23qrs 55.71nopq 53.31efg 52.97def 55.99pqr 55.36lmno 55.47a 51.56bc 54.52ij 54.61ijk 51.61a 48.26bc 52.11b Confidence limits for mean ­95% 53.33 55.67 51.82 56.08 53.59 54.40 55.31 53.93 53.44 53.20 50.86 50.00 50.59 54.48 49.26 54.21 56.93 53.79 56.15 51.56 54.10 54.03 51.67 50.75 53.01 50.98 54.24 54.47 54.66 53.62 55.40 53.12 54.44 52.32 54.30 53.78 51.38 51.04 54.06 53.43 54.77 49.63 52.59 52.69 49.68 46.34 50.99 +95% 57.19 59.53 55.68 59.94 57.45 58.26 59.17 57.79 57.30 57.06 54.72 53.86 54.45 55.88 53.12 58.07 60.79 57.65 60.01 55.42 57.96 57.89 55.53 54.61 56.87 54.83 55.69 58.33 58.52 57.48 59.26 56.98 58.30 56.18 58.16 57.64 55.23 54.90 57.92 57.29 56.16 53.49 56.45 56.54 53.54 50.19 53.24 *Values in the same column with different letters are significantly different (P < 0.05) **Average of each malting quality group. Values in the same column with different letters are significantly different (P < 0.05) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 T a b l e 7 Variations in average -glucan content in barley genotypes of malting quality groups in two years Malting quality groups/Genotype Group A Diosecký 802 Donaris Expres Jubilant Kompakt Levan Nitran Sladar Sladar-new Sladko Slovenský kvalitný Slovenský Dunajský trh Slovenský jemný Average (n=13)** Group B Buciansky Kneifel Dvoran Ezer Fatran Galan Garant Ludan Nadir Nitriansky Export Novum Orbit Vladan Average (n=12)** Group C Amos Argument Cyril Donum Horal Kosan Poprad Pribina Progres Slaven Stabil Svit Zlatan Average (n=13)** Group undetermined Diosecký Kneifel Diosecký Sprinter Pudmerický pivovar Vigasský polojemný Terrasol pivovarský Average (n=5)** -glucan [%]* 4.82qrs 4.41jklmnop 4.29hijklmnop 3.55abc 3.48ab 3.31a 3.31a 4.51mnopqr 4.24fghijklmno 4.53nopqr 4.26ghijklmno 4.83rs 4.00defghi 4.12a 4.29hijklmnop 4.44klmnop 4.27hijklmnop 4.62pqr 4.03defghi 4.40jklmnop 3.78bcd 4.02defghi 3.85cde 3.97defgh 4.58opqr 4.63pqr 4.24a 4.47lmnopq 3.91cdefg 5.05s 4.09defghijk 4.54nopqr 3.99defgh 4.35ijklmnop 4.41jklmnop 4.15gfghijklm 4.39jklmnop 4.03defghi 3.90cdef 4.43klmnop 4.28a 4.56nopqr 4.11defghijkl 4.06defghij 4.21fghijklmn 4.31hijklmnop 4.25a Confidence limits for mean ­95% +95% 4.69 4.29 4.16 3.43 3.36 3.19 3.18 4.38 4.11 4.41 4.13 4.71 3.88 3.97 4.17 4.31 4.15 4.49 3.91 4.28 3.66 3.90 3.73 3.85 4.46 4.50 4.09 4.34 3.78 4.93 3.97 4.42 3.87 4.23 4.29 4.03 4.27 3.90 3.77 4.31 4.14 4.44 3.99 3.94 4.09 4.18 4.02 4.94 4.53 4.41 3.67 3.60 3.44 3.43 4.63 4.36 4.66 4.38 4.95 4.12 4.26 4.41 4.56 4.40 4.74 4.15 4.53 3.91 4.15 3.98 4.10 4.70 4.75 4.39 4.59 4.03 5.17 4.21 4.66 4.11 4.47 4.53 4.28 4.51 4.15 4.02 4.56 4.43 4.69 4.23 4.19 4.33 4.43 4.48 *Values in the same column with different letters are significantly different (P < 0.05) **Average of each malting quality group. Values in the same column with different letters are significantly different (P < 0.05) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 quality group (Table 4), the highest average value of -glucan content was acchieved in the group C (4.28%), and the lowest in the group of malting quality A (4.12%). According to Baik et al. (2008), the average -glucan content was in barley grains of normal starch types (4.4%). In our work, despite this fact there were no strong differences observed in the group; in individual years we found greater differences in -glucan content among genotypes. In the vegetation period of 2010, the highest content of -glucan was determined in the genotypes Slovenský Dunajský trh (5.03%) and Horal (4.80%). In 2011, the highest level of -glucan content was detected in Cyril (5.93%), Diosecký 802 (5.51%), and Diosecký Kneifel (5.25%). However, looking on the average for 2 years, the highest content of -glucan had the genotype Cyril (5.05%) from of the group C; genotypes Diosecký 802 (4.82%) and Slovenský Dunajský trh (4.83%) from the group A; and Vladan (4.63%) and Orbit (4.58%) from the group B (Table 7). Havrlentová et al. (2006) confirmed higher -glucan content in grains of Orbit. Based on the evaluation, we found out that older genotypes had higher content of -glucan in comparison with modern genotypes. According to Fastnaught et al. (1996), higher -glucan content was also in relation to the effect of the heat and drought. Our monitored growing seasons in 2010 and 2011 were within the normal temperature, but they were very wet, and this negatively affected all three analyzed malting quality parameters in barley. There is a recognized negative correlation between the content of starch and protein in a grain; by increasing protein content, the values of other parameters decline with the exception of degree of attenuation and diastatic power (Prugar & Hraska 1989). Higher positive correlations between -glucan and protein content were observed by Güler et al. (2003). According to Hang et al. (2007), simple correlations including the effects of genotype and environmental factors showed that amylose in barley was negatively correlated with -glucan and protein, but on the other hand -glucan was posi- Figure 3. Variability of starch content in barley genotypes during two analyzed years Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 tively correlated with protein. Positive correlations between -glucan and protein and -glucan and grain plumpness are both advantageous to breeders, as each of these traits is desirable for all end uses involving grain consumption. Other authors observed an opposite trend, negative and statistically nonsignificant relationship between -glucan and protein content (Saastamoinen et al. 1992; Welch et al. 1989). Our results correspond with these observations only partially. We observed statistically significant negative correlations (Table 8) between the contents of starch and protein (r = ­0.775; P < 0.01) and between the contents of starch and -glucan (r = ­0.423; P < 0.01). Between the contents of protein and -glucan was observed a statistically significant negative correlation (r = ­0.344; P < 0.05) too. T a b l e 8 Correlation matrix of qualitatively parameters in barley genotypes Starch Protein Starch significant at 0.05 probability level, 0.01 probability level + ß-Glucans ­0.344+ ­0.423 significant at ­0.775 CONCLUSION In the assessment of 43 Slovak spring barley genotypes, we detected significant (P < 0.01) influence of genotype and environmental conditions (years) on protein, starch, and -glucan content in the grain. Geno- Figure 4. Variability of -glucan content in barley genotypes during two analyzed years Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 type × year interaction also had statistically highly significant effects on all monitored parameters. Our study showed that monitored growing seasons (2010, 2011) were within the normal temperature but were very wet, and so this negatively affected all three selected malting quality parameters. The average protein content was the highest in the genotypes from the group with undetermined malting quality. We found out that protein and -glucan contents in older genotypes were higher in comparison with more recent genotypes. Atypical humid years influenced the content of starch in barley grain and reduced the malting quality. The average starch content was lower in all groups and hardly reached 60% in any genotype, even among high quality malting varieties. The average starch content in both older and modern genotypes in the studied set was nearly identical. This confirms a high quality of the older malting varieties. According to malting quality group, the highest average value of -glucan content was in the group of no malting quality (C), and the lowest in the group with best malting quality (A). In individual years we found differences in the -glucan content among genotypes. Despite the atypical years we found out that some good sources of -glucan were newer genotypes such as Cyril (2000), older genotypes such as Orbit (1986) and Vladan (1996), and also historically old genotypes created in the year 1946 such as Diosecký 802 and Slovenský Dunajský trh. These genotypes, mainly old landraces, are a store of many rare genes and properties, such as resistance to drought and earliness and could be use and destined as a donors of not only significant agronomic but also qualitative properties usable in the food industry. Acknowledgements: Thanks to the support within Operational Programme Research and Development for the project "Transfer, use and dissemination of research results of plant genetic resources for food and agriculture" (ITMS: 26220220058), cofinanced from the resources of the European Union Fund for Regional Development. The authors are grateful to Ing. M. Bieliková for analyzing proteins and I. Sugrová for cultivating the plant material. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Agriculture de Gruyter

Variability of the parameters of technological quality in the Slovak spring barley gene pool

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Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 DOI: 10.2478/v10207-012-0012-9 MICHAELA BENKOVÁ*, MICHAELA HAVRLENTOVÁ, UBOMÍR MENDEL, PAVOL HAUPTVOGEL Plant Production Research Center Piesany BENKOVÁ, M. ­ HAVRLENTOVÁ, M ­ MENDEL, . ­ HAUPTVOGEL, P.: Variability of the parameters of technological quality in the Slovak spring barley gene pool. Agriculture (Ponohospodárstvo), vol. 58, 2012, no. 3, pp. 99­112. The total 43 Slovak spring barley genotypes with a year of cultivation or registration from 1938 to 2009 were evaluated in terms of selected parameters like protein, starch, and -glucan contents. Collection of genetic resources consisted of barley malting qualities such as elite ­ A, standard quality ­ B, no malting quality ­ C and five genotypes of unspecified malting quality. Significant (P < 0.01) influence of genotype and environmental conditions (years) and also genotype × year interaction on protein, starch, and -glucan content in the barley grain were detected. The highest average protein content was observed in genotypes from the group with undetermined malting quality. The protein and -glucan contents in older genotypes were higher in comparison with more recent genotypes. The average starch content in both older and modern genotypes in the studied set was nearly identical, which con- firms a high quality of the older malting varieties. According to malting quality groups, the highest average value of -glucan content was in the group of no malting quality (C) and the lowest in the group of best malting quality (A), which is in correspondence with barley malting quality requirements. In individual years differences in the -glucan content were found among genotypes. Despite the atypical years, good sources of -glucan were found out along with modern genotypes such as Cyril and older genotypes such as Orbit and Vladan, but also historically old genotypes were created in the year 1946 such as Diosecký 802 and Slovenský Dunajský trh. Our study has confirmed that these genotypes are donors of not only significant agronomic traits but also qualitative properties, usable in the food industry. Key words: barley, -glucan, starch, protein, genotype, environment Barley (Hordeum vulgare L.) is the second mostly represented crop after wheat in Slovakia. Barley covers an area of 136,300 ha (2011). Barley sowing is very important for the national economy; it is grown as a raw material for the food industry, for feeding animals, and for malt production. Currently 57 varieties of spring barley and 24 winter barley varieties are registered in Slovakia; from this 17 varieties are of Slovak origin (List of registered varieties 2011). Although growing of spring barley is connected with brewing, today a renaissance in the use of barley grain as food has been recorded, first of all in developed countries all over the world (Ehrenbergerová 2006). Here barley is used for production of so-called functional foods. Naked barley has a big role in the food industry, with beneficial nutritional and dietary uses. Its disadvantage is its yield that is lower about 15% in comparison with glumose varieties (Candráková et al. 2000). Biological and agricultural characters of the currently registered barley varieties fulfil conditions of intensive growing; they are adequately resistant to leaf diseases and have good malting quality and high grain yield (Sleziak 2003). According to the National Biodiversity Strategy of Slovakia, barley genetic resources include not only modern varieties, cultivars, and hybrids used mostly in agriculture but also drawn varieties, old landraces, Ing. Michaela Benková, PhD., RNDr. Michaela Havrlentová, PhD., Ing. ubomír Mendel, PhD., Ing. Pavol Hauptvogel, PhD., Plant Production Research Center, Bratislavská cesta 122, 921 68 Piesany, Slovak Republic. E-mail: benkova@vurv.sk (*Corresponding author) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 ecotypes from widespread plant species. and their natural populations. These so-called historical genetic resources have been used as a store of rare genes. Because the long-time selection of barley was constantly influenced by human needs in terms of nutrition and quality of barley, it causes permanent loss of valuable sources of variability in the germplasm. Typically, many modern varieties of spring barley have relatively narrow genetic basis, and to a certain extent they are similar (Kraic et al. 2004; Psota 2009). Quality of barley grain is a complex character, which is subject to complex genetic conditions, considerably affected by agro-ecological growing conditions and depending on the genotype-environment interaction. Barley grain contains 80­88% of solids and 12­20% of water. The dry matter is composed of nitrogen and nitrogen-free organic compounds and inorganic substances (Sleziak 2003). To carbohydrate components belong starch and non-starch polysaccharides (cellulose, hemicellulose, rubber substances, and lignin). Starch content (%) is decisive for extract formation, and therefore it is a significant parameter of barley quality. In malting barley, starch content in dry matter moves around 63­65%, and it should not be lower than 60% (Prugar & Hraska 1989). Starch content depends not only on protein amount but also on the state of growth and sunshine period during the final phases of vegetation. There is a negative correlation between the content of starch and protein in barley grain (Sleziak 2003). The most important components of hemicelluloses and gummy substances are in the barley grain -glucans. From the chemical point of view, -glucan ([1-3][1-4]--D-glucan) consists of glucose units connected by -(1-3)- and -(1-4)- glycosidic bonds in variable proportions, most frequently in the ratio 30 : 70. Grains of barley contain the highest amount of -glucan among all cultivated cereals (Henry et al. 1985). The average -glucan content in barley grains is 7.5% in high amylose, 6.9% in waxy, 6.3% in zero amylose waxy, and 4.4% in normal starch types (Baik et al. 2008). The amount and composition of hemicelluloses and gummy substances and particularly in them containing -glucans and pentosans depends on growing conditions. Short growing season, high temperatures, and drought during growth increase not only the protein content but also the content of non-starch polysaccharide. The effect of genotype is also signifi100 cant (Prugar & Hraska 1989). According to Rey et al. (2009), 66% of variability in the content of -glucan can be attributed to the genotype. A low -glucan and protein content and contrarily higher content of starch in the grain are desirable for malting barley. -glucans fulfill the function of building materials in the endosperm cell walls in contrast to starch, which serve as a storage substance. -glucans stop the entry of enzymes into cells, thus negatively affecting the speed of deciphering of the grain during malting. On the other hand, higher -glucan content is the most important attribute for barley varieties destined for the human food market (Rey et al. 2009). In terms of functional foods, barley -glucans have a great importance as a health-enhancing ingredient (Huth et al. 2000). This component significantly supports the immune system, effectively prevents cardiovascular diseases, and protects from excessive physical or mental stress. It also serves as a antibiotic and assists in chemotherapy and radiotherapy (Charalampopoulos et al. 2002). Based on the assessment of technological quality of selected parameters such as -glucan, protein, and starch content in the barley grain, the aim of our work was to identify the potential of historical, later-created, and new Slovak varieties usable for human nutrition and consumption. MATERIAL AND METHODS Samples of spring barley grains in 43 genotypes of the Slovak origin within a year of cultivation or registration from 1938 to 2009 were obtained from the Gene Bank SR in PPRC Piesany (Table 1). Samples were consequently multiplied and evaluated in the field small-plot trials with the harvest area of 2.5 m2, on the experimental basis in Piesany for two years 2010 and 2011. This experiment was arranged in a randomized block design with two replications. The obtained samples were analyzed for selected parameters of technological quality: -glucans content [%], protein content [%], and starch content [%]. The data obtained have been converted to 100% dry weight basis. Collection of genetic resources consisted of barley malting quality as elite ­ A (13 genotypes), standard quality ­ B (12 genotypes), non-malting quality ­ C (13 genotypes) and five genotypes of unspecified malting quality ­ U (5). Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 T a b l e 1 Characteristics of Slovak spring barley genotypes set released from years 1938­2009 Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 Genotype Diosecký Kneifel Terrasol pivovarský Diosecký 802 Diosecký Sprinter Nitriansky Export Slovenský Dunajský trh Slovenský jemný Slovenský kvalitný Pudmerický pivovar Buciansky Kneifel Vigasský polojemný Dvoran Sladar Fatran Horal Orbit Novum Galan Jubilant Sladko Svit Donum Stabil Garant Kosan Zlatan Amos Kompakt Vladan Progres Expres Cyril Ludan Nitran Ezer Pribina Argument Nadir Poprad Slaven Levan Donaris Sladar new Year of release 1938 1944 1946 1946 1946 1946 1946 1946 1948 1955 1958 1965 1967 1980 1982 1986 1988 1990 1991 1992 1992 1993 1993 1994 1994 1994 1995 1995 1996 1998 1999 2000 2002 2003 2004 2005 2006 2006 2006 2007 2008 2009 2009 Malting quality type unspecified unspecified A unspecified B A A A unspecified B unspecified B A B C B B B A A C C C B C C C A B C A C B A B C C B C C A A A Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 After growing, the grains were dried and milled to pass a 0.5 mm screen using Ultracentrifugal Mill (ZM 100, Retsch GmbH & Co. KG, Haan/Germany). Before each analysis they were stored in hermetic boxes under temperatures of 5°C. Nitrogen content was determined by the Dumas method on the CNS-2000 (Leco Corp., US), and the coefficient 6.25 was applied for recalculation. Starch content was determined by the Ewers polarimetric method (STN 461011-37), and optical activity was recalculated to starch concentration by the coefficient for barley 5.5096. -glucan level was determined using Mixed-linkage eta-glucan assay procedure (Megazyme, Ireland) (McCleary 2011). This method is accepted by the AOAC (Method 995.16) and the AACC (Method 32-23). Samples were suspended and dissolved in a 0.02 M sodium phosphate buffer (pH 6.5), incubated with purified lichenase enzyme, and an aliquot of filtrate was reacted with purified -glucosidase enzyme. The glucose product was assayed using an oxidase/peroxidase reagent recalculated to -glucan content. Analysis of data was performed using statistical software (Statistica 8.0, Statsoft, Inc. 2008) with analysis of variance (ANOVA) and Pearson's correlation coefficient. Differences were considered significant at P < 0.05, unless otherwise specified. Experimental fields were situated in the maize production area, a subtype maize-wheat. Altitude is 162 m; soil is Luvic chernozem (World Reference Base for Soil Resources 2006). The humus horizon is around 40­50 cm deep. Soil reaction of top layers is neutral, and it becomes moderately alkaline in deeper layers. Long-term normal precipitation is 595 mm, with an average annual temperature of 9.2°C (years 1961­1990). Course of vegetation Average temperatures during the vegetation of barley in 2010 and 2011 corresponded to the long-term normal. In 2010 during sprouting there was half the amount of precipitation in comparison to the longterm normal. Therefore, the crop was less involved. During the beginning of the heading period the amount of rainfall was three times heavier when compared to the long-term average. Supernormal rainfall extended the heading period for many varieties of barley and caused a high occurrence of diseases, especially powdery mildew. In 2011, during sprouting precipitation was on an equal level with that of the long-term average. Gradually the precipitation was added at the time of heading and milk ripeness and exceeded the long-term average of more than 40%. There was sufficient rainfall to ensure a rapid increase in leaf area, although it did not Month Precipitations [mm] Temperature [°C] Month Figure 1. Mean monthly temperatures (a) and total monthly precipitation (b) for the years 2010 and 2011 compared to normal (50 years) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 cause the occurrence of diseases, as in 2010, which was reflected in improved grain yield. The detailed course of weather in years 2010 and 2011 is given in the Figure 1. by our results (Figure 2). In the year 2010, intensive rainfall during heading and grain production decreased quality of the malting barley, and protein content was highly increased. The average protein content was statistically different in genotypes from the group with undetermined malting quality (12.89%) (Table 4). The average protein content of genotypes from the group of good malting quality (A) was 11.53% and lowest content was in genotypes of non-malting quality (C), 11.23%. These results were affected by extreme humidity during vegetation in the year 2010. In the whole experiment, the value of protein content fluctuated from 8.76% (Jubilant) to 14.85% (Buciansky Kneifel) (Figure 2). Some genotypes responded very sensitively to the humidity in 2010. For example we recorded the average protein content in Nitran, a malting variety, to be over 14.0%. During the two years we recorded high average protein content at malting quality genotypes of type B (Buciansky Kneifel ­ 14.34%) and similarly high protein content was recorded in genotypes with undetermined malting quality like in Diosecký Kneifel ­ 13.72% and Terrasol pivovarský ­ 14.4% (Table 5). We found out that protein content in older genotypes was higher in comparison with more recent genotypes. On the other hand, contents of starch and -glucan were higher during the 2011 vegetation period (Figures 3, 4). Starch content is decisive for the extract formation, and therefore it is a significant parameter of barley quality. In malting barley, starch content in dry matter moves around 63­65%, and it should not be lower than RESULTS AND DISCUSSION It was important to determine the factors affecting the analyzed traits while assessing a total of 43 Slovak spring barley genotypes in terms of selected characteristics. The ANOVA (Table 2) detected significant (P < 0.01) influence of genotype and environmental conditions (years) on protein, starch, and -glucan content in the barley grain. Genotype × year interaction had a statistically significant effect (P < 0.01) on all monitored characters, too. Protein content is generally considered as the most important parameter of the processing value of malting barley. It can vary within a very wide range (7­18% in dry matter). Good quality malting barleys should have protein content within 10.00­11.5% (Kosa et al. 2000). The average protein content in the monitored genotypes was higher in the year 2010 (12.36%) in contrast to year 2011, when it was only 10.98% (Table 3). The mean value per two years was 11.67%. The distribution of rainfall for barley cultivation is very important. Humidity is needed especially during the stems and grains production, but intensive rainfall increases the nitrogen content (Sleziak 2003), which resulted in higher protein content in the grain. This observation is confirmed T a b l e 2 Analysis of variance of protein, starch and -glucan contents in 43 spring barley genotypes Protein [%] SS 236.78 77.55 82.79 0.47 397.59 MS 5.64 77.55 1.97 0.01 F 1030.5 360.3 Source of variation Genotyp Year Genotyp × Year Residual Total df 42 1 42 86 171 Starch [%] SS 773.90 160.10 327.30 3.50 1264.74 MS 18.40 160.10 7.80 0.01 F 455.0 193.0 ß-glucan [%] SS 24.41 7.91 14.11 1.31 47.73 MS 0.58 7.91 0.34 0.02 F 38.2 520.4 22.1 14174.9 3956.0 significant at 0.01 probability level Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 60% (Prugar & Hraska 1989). Higher starch content affects extract content directly. When there is a lack of starch in the grain, it is not possible to increase the percentage of extract by any other technology. Starch amount depends not only on protein content but also on the state of growth and sunshine period during the final phases of vegetation (Sleziak 2003). Genotypes and experimental years affected variability of the starch content significantly (Table 2). Atypical humid years influenced the content of starch in barley grain, when the average value of starch content in 2010 was only 53.89% and in 2011 it was 55.82% (Table 3). Higher rainfall during grain produce and the ripening period reduced the malting quality. The aver- T a b l e 3 Basic statistical characteristics of qualitatively parameters of barley genotypes in two analyzed years Characteristics Protein [%] Years 2010 2011 Total 2010 Starch [%] 2011 Total 2010 ß-Glucan [%] 2011 Total x 12.36a 10.98b 11.67 53.89 SD 1.27 1.49 1.54 2.59 2.51 2.72 0.50 0.47 0.53 v [%] 10.24 13.58 13.19 4.81 4.49 4.96 12.53 10.51 12.53 Min. 8.81 8.76 8.76 46.12 50.04 46.12 2.88 3.50 2.88 Max. 14.67 14.85 14.85 58.71 60.47 60.47 5.03 5.93 5.93 55.82b 54.85 4.00a 4.43 Values in the same column with different letters are significantly different (P < 0.05). SD - Standard deviation T a b l e 4 Average value of protein, starch and -glucan contents within individual groups of barley genotypes Characteristics Malting quality type A Protein [%] B C U A Starch [%] B C U A ß-Glucan [%] B C U x 11.53 SE 0.18 0.19 0.18 0.29 0.33 0.34 0.33 0.53 0.07 0.07 0.07 0.11 Confidence limits for mean -95% 11.17 11.44 10.88 12.32 54.53 54.29 54.82 51.07 3.98 4.10 4.15 4.04 +95% 11.89 12.18 11.59 13.47 55.83 55.64 56.12 53.16 4.25 4.38 4.42 4.47 11.81a 11.23a 12.89b 55.18a 54.97 52.11 55.47a 4.12a 4.24 4.25 4.28a A - malting quality elite C - no malting quality SE - Standard error B - standard malting quality U - undetermined malting quality Values in the same column with different letters are significantly different (P < 0.05) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 T a b l e 5 Variations in average protein content in barley genotypes of malting quality types in two years Confidence limits for mean ­95% 12.14 10.19 11.47 8.87 11.10 11.52 13.99 11.34 10.66 11.06 11.87 11.99 12.73 11.17 14.27 10.87 9.52 10.39 10.21 11.88 11.40 12.63 12.75 12.88 11.62 12.43 11.44 12.05 11.52 10.28 9.84 11.37 10.62 11.58 10.86 11.01 12.04 11.99 10.76 11.16 10.88 13.64 11.19 12.36 12.94 13.97 12.32 +95% 12.29 10.34 11.62 9.01 11.25 11.67 14.14 11.48 10.81 11.21 12.02 12.14 12.88 11.89 14.42 11.02 9.67 10.54 10.36 12.03 11.54 12.77 12.90 13.03 11.77 12.58 12.18 12.19 11.67 10.43 9.99 11.51 10.77 11.72 11.01 11.15 12.19 12.14 10.91 11.31 11.59 13.79 11.34 12.51 13.09 14.12 13.47 Malting quality groups/Genotype Group A Diosecký 802 Donaris Expres Jubilant Kompakt Levan Nitran Sladar Sladar-new Sladko Slovenský kvalitný Slovenský Dunajský trh Slovenský jemný Average (n=13)** Group B Buciansky Kneifel Dvoran Ezer Fatran Galan Garant Ludan Nadir Nitriansky Export Novum Orbit Vladan Average (n=12)** Group C Amos Argument Cyril Donum Horal Kosan Poprad Pribina Progres Slaven Stabil Svit Zlatan Average (n=13)** Group undetermined Diosecký Kneifel Diosecký Sprinter Pudmerický pivovar Vigasský polojemný Terrasol pivovarský Average (n=5)* Protein [%]* 12.22o 10.27d 11.55klm 8.94a 11.17h 11.60klm 14.06u 11.41ijk 10.73ef 11.13gh 11.95n 12.07no 12.80rs 11.53a 14.34v 10.94fg 9.60b 10.46d 10.29d 11.96n 11.47jkl 12.70qr 12.83rs 12.95s 11.70m 12.50pq 11.81a 12.12no 11.59klm 10.36d 9.92c 11.44ijkl 10.69e 11.65lm 10.94fg 11.08gh 12.11no 12.07no 10.84ef 11.24hi 11.23a 13.72t 11.27hij 12.43p 13.02s 14.04u 12.89b *Values in the same column with different letters are significantly different (P < 0.05) **Average of each malting quality groups. Values in the same column with different letters are significantly different (P < 0.05) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 age starch content was lower in all groups (Table 4) and hardly reached 60% in any genotype, even in the high quality malting varieties (Jubilant, Expres, Nitran). The highest content of starch was determined in the 2011 vegetation period in genotypes Ezer (60.47%) and Galan (59.90%) from the group of malting quality B (Figure 3, Table 3). The average value of starch content during years 2010 and 2011 (Table 6) ranged from 48.26% (Terrasol pivovarský) to 58.86% (Ezer), which is a very low content. Average starch content in older and modern genotypes in the studied set was nearly identical, which confirms a high quality of older malting varieties in spite of the fact that the breeding aims during the last 10 years have been focused on improving malting quality and thus also increasing starch content. Similar to starch also the -glucan content (Figure 4, Table 3) was higher in 2011 (4.43%) compared to 2010 (4.00%). Differences between years and cultivars (Table 2) and interaction of this combination were statistically significant (P < 0.01). In the literature, water stress has been found either to reduce (Macnicol et al. 1993) or to increase (Savin et al. 1996) the -glucan content. According to Zhang et al. (2001), wet days, associated with lower temperatures, were positively correlated with -glucan content. The -glucan is deposited in walls of the endosperm cells during the later stages of grain filling. Thus conditions favorable to endosperm development would increase the accumulation of -glucan in the grain. High precipitation is unfavorable for endosperm development, and high temperatures may shorten the duration of grain filling. Relatively less -glucan will be synthesized and accumulated on the walls of the endosperm cells in comparison with total dry matter, mainly starch and protein, leading on the other hand to lower -glucan content. It can be assumed that similarly in our case the high rainfall in the month of May (Figure 1) in 2010 (164 mm) during the formation of grain caused reduction of -glucan in barley genotypes. Low -glucan and protein content are desirable qualities for malting barley. According to the malting Figure 2. Variability of protein content in barley genotypes in two analyzed years Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 T a b l e 6 Variations in average starch content in barley genotypes of malting quality types in two years Malting quality groups/Genotype Group A Diosecký 802 Donaris Expres Jubilant Kompakt Levan Nitran Sladar Sladar-new Sladko Slovenský kvalitný Slovenský Dunajský trh Slovenský jemný Average (n=13)** Group B Buciansky Kneifel Dvoran Ezer Fatran Galan Garant Ludan Nadir Nitriansky Export Novum Orbit Vladan Average (n=12)** Group C Amos Argument Cyril Donum Horal Kosan Poprad Pribina Progres Slaven Stabil Svit Zlatan Average (n=13)** Group undetermined Diosecký Kneifel Diosecký Sprinter Pudmerický pivovar Vigasský polojemný Terrasol pivovarský Average (n=5)** Starch [%]* 55.26lmn 57.60tu 53.75gh 58.01u 55.52mnop 56.33rs 57.24t 55.86opqr 55.37lmno 55.13klm 52.79de 51.93c 52.52d 55.18a 51.19b 56.14qrs 58.86v 55.72nopq 58.08u 53.49fg 56.03pqrs 55.96pqr 53.60g 52.68d 54.94jkl 52.91de 54.97a 56.40rs 56.59s 55.55mnop 57.33t 55.05jklm 56.37rs 54.25hi 56.23qrs 55.71nopq 53.31efg 52.97def 55.99pqr 55.36lmno 55.47a 51.56bc 54.52ij 54.61ijk 51.61a 48.26bc 52.11b Confidence limits for mean ­95% 53.33 55.67 51.82 56.08 53.59 54.40 55.31 53.93 53.44 53.20 50.86 50.00 50.59 54.48 49.26 54.21 56.93 53.79 56.15 51.56 54.10 54.03 51.67 50.75 53.01 50.98 54.24 54.47 54.66 53.62 55.40 53.12 54.44 52.32 54.30 53.78 51.38 51.04 54.06 53.43 54.77 49.63 52.59 52.69 49.68 46.34 50.99 +95% 57.19 59.53 55.68 59.94 57.45 58.26 59.17 57.79 57.30 57.06 54.72 53.86 54.45 55.88 53.12 58.07 60.79 57.65 60.01 55.42 57.96 57.89 55.53 54.61 56.87 54.83 55.69 58.33 58.52 57.48 59.26 56.98 58.30 56.18 58.16 57.64 55.23 54.90 57.92 57.29 56.16 53.49 56.45 56.54 53.54 50.19 53.24 *Values in the same column with different letters are significantly different (P < 0.05) **Average of each malting quality group. Values in the same column with different letters are significantly different (P < 0.05) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 T a b l e 7 Variations in average -glucan content in barley genotypes of malting quality groups in two years Malting quality groups/Genotype Group A Diosecký 802 Donaris Expres Jubilant Kompakt Levan Nitran Sladar Sladar-new Sladko Slovenský kvalitný Slovenský Dunajský trh Slovenský jemný Average (n=13)** Group B Buciansky Kneifel Dvoran Ezer Fatran Galan Garant Ludan Nadir Nitriansky Export Novum Orbit Vladan Average (n=12)** Group C Amos Argument Cyril Donum Horal Kosan Poprad Pribina Progres Slaven Stabil Svit Zlatan Average (n=13)** Group undetermined Diosecký Kneifel Diosecký Sprinter Pudmerický pivovar Vigasský polojemný Terrasol pivovarský Average (n=5)** -glucan [%]* 4.82qrs 4.41jklmnop 4.29hijklmnop 3.55abc 3.48ab 3.31a 3.31a 4.51mnopqr 4.24fghijklmno 4.53nopqr 4.26ghijklmno 4.83rs 4.00defghi 4.12a 4.29hijklmnop 4.44klmnop 4.27hijklmnop 4.62pqr 4.03defghi 4.40jklmnop 3.78bcd 4.02defghi 3.85cde 3.97defgh 4.58opqr 4.63pqr 4.24a 4.47lmnopq 3.91cdefg 5.05s 4.09defghijk 4.54nopqr 3.99defgh 4.35ijklmnop 4.41jklmnop 4.15gfghijklm 4.39jklmnop 4.03defghi 3.90cdef 4.43klmnop 4.28a 4.56nopqr 4.11defghijkl 4.06defghij 4.21fghijklmn 4.31hijklmnop 4.25a Confidence limits for mean ­95% +95% 4.69 4.29 4.16 3.43 3.36 3.19 3.18 4.38 4.11 4.41 4.13 4.71 3.88 3.97 4.17 4.31 4.15 4.49 3.91 4.28 3.66 3.90 3.73 3.85 4.46 4.50 4.09 4.34 3.78 4.93 3.97 4.42 3.87 4.23 4.29 4.03 4.27 3.90 3.77 4.31 4.14 4.44 3.99 3.94 4.09 4.18 4.02 4.94 4.53 4.41 3.67 3.60 3.44 3.43 4.63 4.36 4.66 4.38 4.95 4.12 4.26 4.41 4.56 4.40 4.74 4.15 4.53 3.91 4.15 3.98 4.10 4.70 4.75 4.39 4.59 4.03 5.17 4.21 4.66 4.11 4.47 4.53 4.28 4.51 4.15 4.02 4.56 4.43 4.69 4.23 4.19 4.33 4.43 4.48 *Values in the same column with different letters are significantly different (P < 0.05) **Average of each malting quality group. Values in the same column with different letters are significantly different (P < 0.05) Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 quality group (Table 4), the highest average value of -glucan content was acchieved in the group C (4.28%), and the lowest in the group of malting quality A (4.12%). According to Baik et al. (2008), the average -glucan content was in barley grains of normal starch types (4.4%). In our work, despite this fact there were no strong differences observed in the group; in individual years we found greater differences in -glucan content among genotypes. In the vegetation period of 2010, the highest content of -glucan was determined in the genotypes Slovenský Dunajský trh (5.03%) and Horal (4.80%). In 2011, the highest level of -glucan content was detected in Cyril (5.93%), Diosecký 802 (5.51%), and Diosecký Kneifel (5.25%). However, looking on the average for 2 years, the highest content of -glucan had the genotype Cyril (5.05%) from of the group C; genotypes Diosecký 802 (4.82%) and Slovenský Dunajský trh (4.83%) from the group A; and Vladan (4.63%) and Orbit (4.58%) from the group B (Table 7). Havrlentová et al. (2006) confirmed higher -glucan content in grains of Orbit. Based on the evaluation, we found out that older genotypes had higher content of -glucan in comparison with modern genotypes. According to Fastnaught et al. (1996), higher -glucan content was also in relation to the effect of the heat and drought. Our monitored growing seasons in 2010 and 2011 were within the normal temperature, but they were very wet, and this negatively affected all three analyzed malting quality parameters in barley. There is a recognized negative correlation between the content of starch and protein in a grain; by increasing protein content, the values of other parameters decline with the exception of degree of attenuation and diastatic power (Prugar & Hraska 1989). Higher positive correlations between -glucan and protein content were observed by Güler et al. (2003). According to Hang et al. (2007), simple correlations including the effects of genotype and environmental factors showed that amylose in barley was negatively correlated with -glucan and protein, but on the other hand -glucan was posi- Figure 3. Variability of starch content in barley genotypes during two analyzed years Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 tively correlated with protein. Positive correlations between -glucan and protein and -glucan and grain plumpness are both advantageous to breeders, as each of these traits is desirable for all end uses involving grain consumption. Other authors observed an opposite trend, negative and statistically nonsignificant relationship between -glucan and protein content (Saastamoinen et al. 1992; Welch et al. 1989). Our results correspond with these observations only partially. We observed statistically significant negative correlations (Table 8) between the contents of starch and protein (r = ­0.775; P < 0.01) and between the contents of starch and -glucan (r = ­0.423; P < 0.01). Between the contents of protein and -glucan was observed a statistically significant negative correlation (r = ­0.344; P < 0.05) too. T a b l e 8 Correlation matrix of qualitatively parameters in barley genotypes Starch Protein Starch significant at 0.05 probability level, 0.01 probability level + ß-Glucans ­0.344+ ­0.423 significant at ­0.775 CONCLUSION In the assessment of 43 Slovak spring barley genotypes, we detected significant (P < 0.01) influence of genotype and environmental conditions (years) on protein, starch, and -glucan content in the grain. Geno- Figure 4. Variability of -glucan content in barley genotypes during two analyzed years Agriculture (Ponohospodárstvo), 58, 2012 (3): 99-112 type × year interaction also had statistically highly significant effects on all monitored parameters. Our study showed that monitored growing seasons (2010, 2011) were within the normal temperature but were very wet, and so this negatively affected all three selected malting quality parameters. The average protein content was the highest in the genotypes from the group with undetermined malting quality. We found out that protein and -glucan contents in older genotypes were higher in comparison with more recent genotypes. Atypical humid years influenced the content of starch in barley grain and reduced the malting quality. The average starch content was lower in all groups and hardly reached 60% in any genotype, even among high quality malting varieties. The average starch content in both older and modern genotypes in the studied set was nearly identical. This confirms a high quality of the older malting varieties. According to malting quality group, the highest average value of -glucan content was in the group of no malting quality (C), and the lowest in the group with best malting quality (A). In individual years we found differences in the -glucan content among genotypes. Despite the atypical years we found out that some good sources of -glucan were newer genotypes such as Cyril (2000), older genotypes such as Orbit (1986) and Vladan (1996), and also historically old genotypes created in the year 1946 such as Diosecký 802 and Slovenský Dunajský trh. These genotypes, mainly old landraces, are a store of many rare genes and properties, such as resistance to drought and earliness and could be use and destined as a donors of not only significant agronomic but also qualitative properties usable in the food industry. Acknowledgements: Thanks to the support within Operational Programme Research and Development for the project "Transfer, use and dissemination of research results of plant genetic resources for food and agriculture" (ITMS: 26220220058), cofinanced from the resources of the European Union Fund for Regional Development. The authors are grateful to Ing. M. Bieliková for analyzing proteins and I. Sugrová for cultivating the plant material.

Journal

Agriculturede Gruyter

Published: Nov 8, 2012

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