INSTITUTE OF AGRICULTURAL RESEARCH 'SERBIA'
Center for Small Grains, Save Kovacevica 31, Kragujevac 34000, Yugoslavia.
M. Jelic, S. Lomovic, S. Zivanovic, J. Milivojevic, and J. Stojanovic.
Introduction. High soil acidity and Al concentration are very serious problems in areas of intensive wheat production. Over 60 % of total arable lands in Yugoslavia are acid soils. A reduction in grain yield of winter wheat varieties was observed on these soils. A high Al concentration in the soil is very toxic to wheat plants. Plants can attempt to alleviate Al phytotoxicity, but winter wheat varieties and ecotypes differ in their ability. Great differences between particular wheat genotypes exist with respect to their tolerance to high soil acidity and Al concentration. Low-acidity soils cause a very complex problem, and numerous approaches (cultural, management, and lime application) are required. One possible solution is to choose and grow tolerant genotypes. To this end, we tested the degree of resistance of the more important commercial varieties to Al phytotoxicity.
Results. The experiment was made in a pot trial using Jarusice and Kragujevac hard clay soils. The Jarusice and Kragujevac soils had pHs of 4.3 and 5.5 and Al concentrations of 25 and 0 mg/kg, respectively. The experiment was conducted over a 2-year period (1997-98) in greenhouse conditions. The changes in some production traits of the studied winter wheat varieties in an acid soil are shown in Table 1.
|Variety||Shoot yield (g/plant)||Grain yield (g/plant)||No of tillers /plant||Harvest index|
The tested varieties had very different responses to low soil pH and high soil Al concentration. The highest shoot and grain yields on very acid soil were in PKB, Ranka, Europa, and Dicna. The reduction in grain yield of these varieties was considerably lower in comparison to the other tested varieties grown in the control soil. PKB and Ranka had decreased shoot yields of 22 and 74 % and grain yields of 66 and 117 %, respectively, compared to the control. The decrease in harvest index in these two varieties compared to those grown in the control soil was 12.9 and 9.3 %, respectively. Good tolerance to the detrimental impacts of high acidity and Al concentration was found in the varieties Takovcanka and Kosmajka.
On the other hand, a low degree of tolerance was observed in Zemunka, Partizanka, and A- 21. Zemunka and Partizanka had shoot and grain yields reduced by 2.6 and 2.0 and 6.3 and 4 times, respectively, than when grown in the control soil. Zemunka and Partizanka also had lower harvest index by 27 and 19 %, respectively, when grown in acid than in the control soil.
The Yugoslav winter wheat varieties possessed some degree of tolerance to low soil pH and high soil Al concentration. The greatest degree of tolerance was in PKB Krupna, Ranka, Europa, and Dicna, whereras Takovcanka and Kosmajka varieties had a good, but lower, degree of tolerance.
The above-mentioned genotypes could be interesting, not only from the aspect of their advantage for growing in acid soils, but also as important sources of genes for tolerance to low pH and high Al concentration for future wheat breeding.
M. Kuburovic*, M. Pavlovic, M. Milovanovic, Veselinka Zecevic,
and Milomirka Madic*.
* Faculty of Agronomy, Cacak, Yugoslavia.
Introduction. One condition for high grain yield in wheat is resistance to lodging, in addition to resistance for disease and drought. Lodging-resistant wheat varieties generally have shorter stems, although there are some exceptions. Until now, the wheat breeding program at the Center for Small Grains in Kragujevac focused special attention on stem shortening to improve lodging resistance. Our goal is to create new winter wheat varieties with stem heights between 70-80 cm. Only certain changes in a plant's architecture lead to yield increases, and extreme shortening is not desirable (Djokic 1990). The winter wheat breeding program focuses on genetic divergence, high yield, and quality characteristics that will enable high and stable grain yields in different years and environmental conditions (Borojevic 1981). Breeding and creating new varieties of winter wheat at the Center for Small Grains - Kragujevac combines high yield and excellent or very good quality, while retaining other positive traits as much as possible (Popovic 1989). In this report, we present the results of investigations of some perspective lines of winter wheat created at our institute.
Material and methods. Eight lines obtained by single or complex crosses of different genotypes of winter wheat were included in micro trials. We used the following lines as crossing parents for their resistance to low temperature and lodging: Dijana, Marija, Skopljanka, SK2, OS. 5-68/11, Evropa, Srbijanka, Studenica, Kg. 8/1222, Kg. 2169, and Jednota (a variety with high quality) and two lines resistant to diseases (B-159 and PI-159102). These parental genotypes originated from the Institutes of Novi Sad and Kragujevac (Yugoslavia), Zagreb and Osijek (Croatia), and Skopje (FYROM). Desirable traits of the parents and their ancestors (high grain yield, good technological quality, and good lodging resistance) were combined in new lines by genetic recombination. Lines were selected using the pedigree method and tested in wheat trials (5 x 4 m2) in the 1997 and 1998 growing seasons and in a main wheat trial (8 x 4 m2) in 1998, on experimental fields at Kragujevac. The majority of these lines also were tested in the 1998 season at a few locations in the Republic of Serbia (Sremska Mitrovica and Sombor-Vojvodina, and Pec-Kosovo, and Metochia). The grain yield was compared to that of the winter wheat variety Pobeda, which is one of the standards of the Federal Commission for Variety Approval. Technological quality of grain, flour, and bread were examined in the farinological laboratory at Kragujevac by the standard methods.
Results and discussion. The most important trait for the majority of wheat producers in Yugoslavia is grain yield per hectare. Grain yield is a very complex characteristic, controlled by numerous genes and environmental factors (Borojevic 1981). Therefore, breeding for high grain yield is very complex and difficult. New lines of winter wheat from Kragujevac have high and stable grain yields. The majority of lines achieved higher grain yield than the standard Pobeda, averaged over both years of trials and at all localities. The highest yielding were lines Kg. 191/1, Kg. 1/1, and Kg. 131/94, which surpassed the grain yield of Pobeda by an average of more than 800 kg/ha. All winter wheat lines and Pobeda had higher grain yields in 1998 than in 1997 at Kragujevac. The winter wheats examined at other locations had higher grain yield at Sombor than at Sremska Mitrovica and Pec. The maximum yield was in the wheat line Kg. 14/1 in Kragujevac (9.556 t/ha), but this line yielded the least in Pec (5.800 t/ha). At the experimental fields in Kragujevac, line Kg. 131/94 (9.350 t/ha) was the highest yielder. This line also had high and stable grain yields at other localities, in addition to lines Kg. 191/1 and Kg. 1/1 (Table 2).
|Genotype||Pedigree||Kragujevac *||Sremska (1998) **||Mean||± from Pobeda|
|Kg. 191/1||PI159102/Evropa//Studenica/3/Kg. 2086||8.033||9.107||9.330||6.680||---||9.031||8.436||+899|
|* There were two trials in 1998 at Kragujevac.
** Trials at Pec, Sremska Mitrovica, and Sombor were all during the 1998 season.
Plant height of the investigated lines of winter wheat ranked between 71-82 cm, which was 1-12 cm shorter than in Pobeda. All wheat lines except Kg. 3059-4/93 are very resistant to lodging. These lines also have medium-large to large kernel sizes, and 1,000-kernel weights between 37.00 and 44.05 g. In addition to high quality, the hectoliter mass also could be a good indicator of the biological plasticity of a variety and its better resistance to drought and high temperatures at grain filling. A majority of the lines, as well as Pobeda, had a hectoliter mass above 80 kg (Table 3).
|Genotype||Plant height (cm)||1,000-kernel weight (g)||Hectoliter mass (kg)||Lodging (0-9)|
Sedimentation values (Zeleny) of the investigated wheat lines ranged from 29-61 ml. All lines had lower sedimentation values than the Pobeda check, except for Kg. 381, which was similar. According to many studies, sedimentation value can be considered as a good indirect parameter of bread-making quality (Petric et al. 1982). However, some new investigations on wheat varieties from crosses of genotypes that have different genes controlling the technological quality do not always give this result (Misic and Mladenov 1998). The investigated lines had lower wet-gluten content (19.75-36.21%) relative to Pobeda, which had the highest value of 40.06 %. The quality number (farinograph) was the highest in lines Kg. 381, Kg. 110/95, and Kg. 3059-4/93. In all other lines, the quality number was lower in relation to the Pobeda check. According to the values for quality number and water retention capacity, the lines were separated into quality groups. Wheat lines Kg. 381, Kg. 110/95, Kg. 3059-4/93, and Pobeda belong to A1 and A2 quality groups, and the rest of lines are in either the B1 or B2 quality group.
The most important bread-making quality parameters are bread yield, bread volume, and crumb value (Kovacev-Djolai et al. 1987). According to bread volume and crumb value parameters, the best quality wheats were Pobeda and Kg. 3059-4/93. A new line Kg. 3059-4/93 also has a majority of technological quality parameters at levels similar to that of Pobeda. High values for these characteristics also are found in line Kg. 381 (Table 4).
|Genotype||Sedementation value (Zeleny, ml)||Wet glutin content (%)||Quality number||Quality group||Bread volume (ml)||Crumb value *|
|* Crumb value is the sum of estimates of bread-crumb elasticity and refinement of the structure of pores on a scale of 0.5-7.|
From all investigated lines of winter wheat created in Center for Small Grains-Kragujevac, the most promising are Kg. 381 and Kg. 191/1. These lines possess high and stable grain yield and excellent or very good technological quality, as well as good lodging resistance. Thus, in a single variety, it is possible to unite high yield potential, excellent or very good technological quality, and other desirable characteristics (Misic et al. 1987). The majority of these lines is included in the network of trials of the Yugoslav Commission for Varieties Approval.
Conclusions. in the micro trials at the Center for Small Grains in Kragujevac and three other locations, we examined eight perspective winter wheat lines during two seasons relative to the standard variety Pobeda. A majority of the investigated lines yielded higher than Pobeda.
Nearly all the wheat lines had shorter stems and better lodging resistance than Pobeda. These lines had medium-large to large kernels, and majority had a hectoliter mass above 80 kg. Pobeda and line Kg. 3059-4/93 had the best technological quality parameters. Perspective wheat varieties include Kg. 381 and Kg. 191/1, because they have high and stable grain yield, excellent or very good technological quality, and very good lodging resistance. Some of these lines are included in trials of the Yugoslav Commission for Varieties Approval.
Desimir Knezevic, Veselinka Zecevic, Dusan Urosevic, Milanko Pavlovic, Ivana Marinkovic, Danica Micanovic, and Vesna Urosevic.
Introduction. Wheat grain and its products are very important in human nutrition. The great nutritional importance of wheat has stimulated the investigation of quality parameters. During the last few decades, significant advancements have been made in biochemical, genetic, and molecular biology studies of protein components. Proteins play major roles in determining quality of grain, flour, dough, and bread. A number of genes encoding proteins have been isolated and sequenced. Very intensive investigations of milling, dough forming, and baking properties have been conducted in the last few decades. The results of these investigations, along with the results of a study of morphological traits, have led to new methods of breeding and wheat production.
To resolve the genetics of grain quality in wheat, the main investigations focused on protein sedimentation volume, protein and gluten contents, grain hardness, and farinograph characteristics, which are controlled genetically. A combination of these parameters and flour protein content can be used as a basis for estimating the technological quality of selected materials. To improve wheat grain quality, identifying biotype polymorphisms with numerous favorable traits and gene donors controlling high protein content with high grain yield is important (Bebyakin 1985).
Materials and methods. The technological quality of 10 winter wheat cultivars created at the Center for Small Grains were studied. We used the cultivars KG-56, KG-56S, Srbijanka, Bistrica, Takovcanka, Levcanka, Gruza, Toplica, and KG-100. The quality of the wheat cultivars was estimated on the basis of protein sedimentation volume, water absorption, gluten content, loaf volume, bread yield, and crumb number. Standard milling was performed with a Buller-type MLU-202 experimental mill (Buller, Uzwill, Switzerland). Sedimentation value was analyzed according to Zeleny, modified so that 2 or 5 g of wheat could be evaluated satisfactorily. Rheological quality was analyzed with a micro-Brabender farinograph using 10-g flour sample.
Results-protein sedimentation volume. Differences in technological quality parameters among the cultivars are shown in Table 5. Sedimentation volume varied between 33 ml (Levcanka) and 61 ml (Toplica). Cultivars with a sedimentation volume higher than 40 ml in the first quality group included KG-56S, Takovcanka, Gruza, and Toplica. The remaining cultivars belong to the second quality group. In the second year of analysis, the highest sedimentation volume was 53 ml in Tolica, and the lowest was 28 ml in KG-100 (Table 6). The sedimentation volumes of the cultivars were different in different growing seasons.
A high protein-sedimentation volume depends on protein contents and the amounts of gliadins and glutenins and the gliadin/glutenin ratio. Glutenin content is related directly to protein content and influences sedimentation volume (Kevresan et al. 1990). High protein-sedimentation values indicate high protein content and good gluten quality (Vombergar 1985; Knezevic and Menkovska 1994). Glutenin content had positive genetic correlations with the technological quality of flour and sedimentation volume, whereas gliadin content had negative correlations. The HMW-glutenin subunits 5+10 had a positive correlation with protein sedimentation (Lorenzo et al. 1987; Pogna et al. 1990). The influence of HMW-glutenin subunits on protein-sedimentation volume (Vapa and Mihaljev 1990) and gluten content and loaf volume (Menkovska et al. 1995) have been established. Cultivars with the Glu-A1 HMW-glutenin subunit fractions 2* and 1 have higher sedimentation volumes than cultivars that have the null allele on chromosome 1A (Knezevic et al. 1993).
The cultivar Toplica has high values for these parameters. Protein-sedimentation volume has a positive correlation with other quality parameters such as gluten quality and loaf volume (Zuoji et al. 1989), and this was confirmed by the results of this study. Toplica had the highest loaf volume (470 ml) in the second year of trials.
A positive correlation between the value of some gliadins and the sedimentation value was established by Sasek et al. (1987). Generally, gliadins have negative correlations with technological quality of flour and sedimentation volume.
Gluten quality and content. Different values of gluten content in wheat cultivars were established in this study. On average, higher values for gluten content occurred in cultivars grown in 1997 than in the same cultivars grown during 1998. The cultivar Toplica had the highest gluten content (39.19 %) in the first trial, and KG-100 had the lowest (28.37 %). During the 1998 season, Bistrica had the highest gluten content, and KG-100 had the lowest (24.81 %).
Grain gluten content varied from 16-52 % (crude) and 5-20 % (dry) and depended on the cultivar and growing conditions (Pavlovic et al. 1994). Gluten content depends on grain consistency more than on grain size. Such changes are similar for baking quality of the flour. Gluten of high quality depends on temperature and moisture conditions during maturation. High temperature and low moisture produce a strong gluten with less extensibility, and the opposite conditions produce flours with weak glutens and extensible doughs (Kodanev 1976). Gluten is formed in the early stages of ripening (milk stage), but its quality changes during maturity to the final characteristics. Later, quality changes in gluten are not important.
Gluten color changes from an intense green to bright yellow at maturity. Gluten structure has a great influence on flour rheological properties and quality. Gluten quality depends on the ability of dough to keep CO2 from fermentation in gas cells in order to provide loaf volume and bread crumb. A high positive correlation (r = 0.9) exists between protein content and grain gluten content in wheat. Gluten quality depends on the amount and ratio of HMW and LMW glutenins, gliadins, their structure, and amino acid content. HMW-glutenin subunits join end-to-end through disulfide bonds to provide a backbone for the gluten complex (Pogna et al. 1996).
Loaf properties. The analyzed cultivars differed in water absorption (Table 5). In the first year of analysis, Toplica was the highest at 68.6 ml and in KG-56 was the lowest at 55.8 ml. Water absorption in the second year was highest in Gruza (68 ml) and lowest in KG-100 (58.2 ml) (Table 6). These differences indicate the characteristics of bread-making quality of flour in wheat cultivars.
|Cultivar||Sedimentation value (ml)||Dry gluten||Water absorption capacity||Quality subgroup||Bread volume ml/100 g of flour||Bread volume g/100 g of flour||Crumb number|
|Cultivar||Sedimentation value (ml)||Dry gluten||Water absorption capacity||Quality subgroup||Bread volume ml/100 g of flour||Bread volume g/100 g of flour||Crumb number|
A flour of good bread-making quality should have a high water absorption, a medium to medium-long mixing requirement, a small to medium oxidation requirement, satisfactory mixing tolerance and dough-handling properties, and good loaf volume. The cultivar also should yield a loaf that has a good internal crumb grain and color (Finney et al. 1987). Baking properties are influenced by the presence of proteins in the endosperm of the grain. Gliadins and glutenins are the predominant proteins in the endosperm. Glutenins are known to contribute to protein quality, playing an important role in the bread-making process.
The results of loaf properties are presented in Tables 5 and 6. In the first year of analysis, the highest loaf volume was in the cultivars Bistrica and Levcanka (430 ml), and the lowest (310 ml) was in KG-56. The loaf volume averages were higher in the second year than in the first. The highest loaf volume (470 ml) was in Toplica, and the lowest (400 ml) in KG-56. Other cultivars had loaf volumes greater than 400 ml. Both Bistica and Levcanka had lower loaf volumes (400 ml) than in the previous year (430 ml).
Loaf volume is related inversely to the proportion of acetic acid-soluble glutenin. Orth and Bushuk (1973) found no correlation between the proportions of albumins, globulins, and gliadins and bread-making quality. Thus, they concluded that glutenin was responsible for the variation in loaf volume at a constant protein content among varieties of bread wheat. The highest value of bread yield was in Levcanka in both years of the study, and the lowest value was in Studenica (Tables 5 and 6).
Conclusions. Estimation of the technological quality of Yugoslav wheat was conducted by using micro methods to determine the following parameters: protein sedimentation volume, gluten quality and content, and bread-baking and loaf parameters.
Protein content is the most important parameter to assess wheat quality. Success of breeding depends mostly on heritable traits and methods to identify the quality of grain in early hybrid generations. Gluten quality depends on the amount and ratio of HMW and LMW glutenins, gliadins, their structure, and amino acid content. Cultivars Toplica, Takovcanka, and Levcanka expressed high values of tested technological quality parameters and can be used as a parents in the wheat breeding programs.
Increasing grain quality by the wheat breeding process is difficult because of the negative correlation between grain protein content and grain yield, but a permanent goal of Yugoslav wheat breeders is to resolve this.