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In ecological field experiment involving common wheat varieties, several quality parameters were analyzed, which express different aspects of grain quality. Objective of the study was to establish in detail the main relations about the influence of the conditions (location and year) and their interaction with the genotype on each of the parameters, separately. The accepted hypothesis was that the growing conditions have a different strength and direction of effect on each parameter, which should ultimately be reflected in a unique way on the performance of each variety of the studied group. In four locations, which represent a sample of the main grain-producing regions of the country, twentyfour varieties of common winter wheat were investigated. Five indexes of grain quality were analyzed as follows: Sedimentation index (Zeleny); Deformation energy (W); P/L alveograph configuration ratio (P/L); Swelling index (G); Dough stability time (Dstab). All possible aspects of the interaction of genotype (GEN), environment (ENV) as well as the interaction between them (GEN*ENV) were investigated. Statistical approaches and methods that are specialized for this purpose were used. Each of the three main factors - "location", "year" and "genotype" influenced the variation of the group of varieties through the changes of the conditions, independently and in combination with each other. In this combination of effects expressed as (GEN*ENV) the most essential role was the "location". The established significant interaction caused an adequate (linear) and inadequate (non-linear) change of the varieties, relative to those of the conditions. For the majority of parameters, this change was mostly linear (PC1=70%), with the exception of the P/L (alveograph configuration ratio), where both effects had parity (PC1 ≈PC2-4). The environments in the locations during individual seasons had high degree of repeatability (H2=0.75 - 0.94), which allows a high degree of prediction of the values of each single parameter. All parameters were affected to varying degrees by the studied factors and the interaction between them. The influence of the conditions was relatively the strongest on the Dough stability time index (Dstab), and the Swelling index (G) was most closely related to the genetic predisposition of the variety. The effects of the interaction of the genotype with the environments (GEN*ENV) made up about 20-30% of the total variation of three of the parameters, for Deformation energy index (W) the effect reached 40%, and for the Dough stability time index (Dstab) it was only about 13%. The environments during the seasons were the cause of a dynamic change of the correlations between the yield and some of the parameters, in some of the locations studied. Probably, this was directly dependent on the specific combination between the levels of extraction and the level of a given parameter. [ABSTRACT FROM AUTHOR]

The aim of the study was to assess the size and stability of grain yield of a group of varieties grown in different conditions of the country. The study included a total of forty samples of winter common wheat, developed by Agronom breeding company. The field experiment was conducted in three typical grain production locations of the country: Dobrich, Trastenik and Straldja, in the period 2017-2019. All aspects of the interaction of varieties with environmental conditions were analyzed using two statistical programs PBSTAT and GEA-R. Through their application, 16 different parameters were calculated, through the ranks of which stability was assessed. The data obtained from the individual parameters were subjected to direct comparison with the modules of the programs GenStat 15, JMP 14 and GGE Biplot 6.3, which have a visual representation of the results for the level of yield and stability of each cultivar. The stability of only the varieties with higher yield than the check cultivar was monitored. Their stability was monitored and measured through all software products before a conclusion was made about its level. The share of genotype and its interaction with environment was only about 20% of the total variation. The conditions in the individual locations have a significant impact on the yield performance, which causes a strong change in the yield in the individual varieties. It causes a drastic change in the rank of the yield by locations. Against the background of strong G x E interaction, only six varieties have been identified: ABC Aldo, ABC Grosso, ABC Lombardya, ABC Klausius, ABC Zigmund and ABC Navo, whose average yields were proven to be higher than those of the check variety LG Avenue. Their high productive potential was realized to a degree that guarantees high stability in changing conditions of the used regions. Current statistical models were effective in quickly and efficiently determining all possible levels of combination between genotype yield and stability. The newly created varieties showed higher stability than the already established ones, as their productivity was at a much higher level. Breeding, accompanied by ecological tests of many advanced lines, shows that it was possible to combine high yields with relatively high stability with enough varieties for successful zoning throughout the country. [ABSTRACT FROM AUTHOR]

Data from different multi-environmental trails (MET) were analysed, including different number of varieties, number of locations and different research periods. The first experiment (24 PhD) included 24 wheat varieties that were studied in five locations of the country over a period of four years (2009-2012). The second field experiment (40 ABC) consists of 40 new advanced wheat lines and cultivars, which were studied in three locations over a three-year period (2017-2019). The grain yield datasets from the two experiments were used to make a direct comparison of various statistical parameters to assess the genotype stability against the background of significant growing conditions. The study involves the use of several statistical packages that are specialized for this purpose. Based on the ranking assessment of the values of each statistical parameter, a critical analysis was made of its relationship with the yield, for each dataset separately. For this purpose, the possibilities of correlation, principal component and cluster analyses were used. Parameters for which information differs between datasets or between statistical packages are removed from the analysis list. The final set of 31 parameters was analysed according to the set goal, after a statistically justified possibility to merge the two datasets. Most of the rank parameters do not show correlation with grain yield. The units are the parameters, the correlation of which is either positive (Pi, Ysi, TOP, λ) or, respectively, negative (DJi, NP(1), CVi]). The analysis of the data through different statistical approaches shows that the parameters correspond to the dynamic concept of stability assessment. Only one of the parameters (θi) is related to static stability assessment. In the presence of many more effective than it, it should not be applied because it is an exception from the analysed group. The groups of parameters of the regression coefficient (bi), the deviation from the regression line (s2di), ecovalence (W2i) and the stability variance (σ²i), give objective information about the behaviour of the variety in environmental conditions and it is not influenced by software. Some of the non-parametric [S(i) NP(i)] assessment methods provide diametrically opposed information for stability because of differences arising from either the dataset or the software used. Suitable for stability assessment are non-parametric approaches - [S(1) and S(2)], which is fully confirmed by the three software packages. Each of the used software packages contains a set of parameters, the application of which as a set gives correct information about all aspects of the wheat stability [ABSTRACT FROM AUTHOR]

Growing conditions play a significant role in the yield and grain quality of winter wheat. Global climate changes and in particular in the meteorological situation in the regions typical for the crop presuppose conducting research on the newly created breeding materials for grain quality. The aim of the study is to determine the nature and magnitude of the change in important parameters of grain quality, under the influence of typical environmental conditions for growing common wheat. The working hypothesis suggests that most of the parameters have a good genetic basis that would allow the selection to lead to their increase. In a multi environmental field experiment involving five test locations over three consecutive years, changes in eight grain quality parameters were investigated reflecting different aspects of the end-use quality. The study involved 40 samples of wheat developed by the breeding company "Agronom" in the last 20 years. With the help of modern methods for statistical analysis, the effect of the main breeding factors "location", "year" and "genotype", the limits of variation and the correlations between them have been established. The real possibilities for selection and breeding of each parameter have been analyzed, against the background of the rest of the group. Quality parameters change significantly from the three factors studied. The interaction "genotype x year" has the strongest influence on each of them. The "location x genotype" interaction is not a factor that affects the parameters. Only Deformation energy shows a significant share of the genotype, while the other two factors have a negligible influence on it. Each of the studied parameters, without exception, changes both adequately (linearly, IPC1) and inadequately (nonlinearly, IPC2) when the conditions change during the studied seasons. This nature of change is the reason for the relatively weak positive correlations between the parameters, as well as for their low heritability coefficients in a broad sense. Against the background of the data, the values of Genetic advance are indicated, with which each of them can be increased by selection. There are both positive and negative correlations between the parameters, the direction and value of which must be taken into account in the attempt to change them. An effective selection can be made on the parameters Extensibility index, Deformation energy and P/L ratio which have the strongest genetic control (H2> 0.60), which against the background of the strong influence of the environment ("location", "year", "location x year") can lead to genetic advantage with 12% (Extensibility index), 17% (Deformation energy), 51% (P/L) of their present value. A selection based on PC or Wet gluten content parameters that have a direct effect on overall quality can also be effective (H2 =0.58-0.63). Instead, it would be more prudent to monitor, not so much their quantitative, but their qualitative composition, the accumulation of known or new alleles of glutenins (Glu) and gliadins (Gli), for which there is specific information that they are directly related to high grain quality. [ABSTRACT FROM AUTHOR]

Information on the relationships between quantitative traits affecting yields is extremely important for winter wheat. For it, the annual genotype*environment interaction is palpable and often masks the influence of individual traits on grain yield. The aim of the study is to determine the traits through the selection of which the grain yield could be significantly increased in the future. The data from three field multifactorial experiments were used (FERT, PGR, ABC), in which a significant influence of various factors (year, point, density, fertilization) on the size and variation of all studied traits was established. In the database thus formed the observed strong variance in the values of the traits is a great prerequisite for the established correlations to be accepted with a high degree of reliability. The mutual influence in the formation of each of the traits is a good basis for their grouping, according to the type of their effect on yield. 1) The characteristics, number of grains per m2 (NGm), grain weight per spike (WGS) and number of productive tillers per m2 (NPT) have a significantly positive effect on grain yield, 2) the weight per 1000 grains (TGW) and number of grains in spike (NGS) are traits that have a direct effect, but it is unstable in manifestation and 3) the traits, as height of stem (HOS), total plant biomass (TBM), and harvest index (HI) do not show a direct effect on grain yields. A significant increase in yield in the breeding of winter wheat can be achieved by increasing the number of grains per unit area (NGm). This is possible while maintaining the achieved level of number of grains in spike (NGS) with a parallel increase of tillering productive ability (NPT). The increase of this trait by selection should be taken into account when reducing the grain size (TGW). This will increase the chance of increasing the number of grains in the spike (NGS), will reduce the weight of the grain per spike (WGS), which in turn will be a prerequisite for optimizing the stability of lodging. [ABSTRACT FROM AUTHOR]

Wheat is a crop with a very long growing season, during which it is subjected to prolonged exposure to many environmental factors. For this reason, the interaction of genotype with conditions is very common for any character of wheat. This study aims to determine whether the grain yield is affected by the change of the ear emergence date (EED) in various environments. In a four-year period, 30 current for national real grain production winter wheat varieties were studied. The EED and grain yield (GY) were studied as quantitative traits within five locations of the country having various soil and climatic conditions. Using several statistical programs, genotype x environment interaction of two traits was analyzed. The emphasis on data analysis was whether changes of traits due to the conditions were related and that the optimization of the ear emergence date could serve as a breeding tool for increasing grain yield. The date of ear emergence and grain yield are traits that are reliably influenced by growing conditions. The change in the date of emergence is mainly of the linear type, while the grain yield shows linear and nonlinear type changes in the same environmental conditions. It was found that the key roles in the change of characteristics are the conditions of the year, with the relatively weakest impact of the genotype on them. There is a positive relationship between the two traits, although their change depends on environmental factors. Although they change to different degrees and in relation to each other, there is a positive correlation between them. The more favorable the environmental conditions, the weaker the relationship between these two traits and vice versa. Under changing climatic conditions, the change in the relationship between the two traits is a signal of the need to create different varieties by date of ear emergence in order to obtain higher yields in the future. [ABSTRACT FROM AUTHOR]

In a series of field trials, a database of quantitative traits associated with winter wheat grain yield has been collected. The aim of the present study is to determine the relationships between the winter wheat (Triticum aestivum L.) traits of productivity in environments causing the maximum possible variation of each of the traits. In order to determine the correlations between the quantitative characters studied, all possible statistical methods have been applied (regression analysis, PCA, Multiple Correspondence analysis), which complement each other. It was found that the nature of the correlations between traits depends to a large extent on the methods for their evaluation. There are high and significant correlations between grain yields and the grain number per spike (weight of grain per spike and number of grains per m2) even under strong genotype by environment interaction of all the traits in trails. The established results are related to possible options for increasing winter wheat grain yield by breeding. [ABSTRACT FROM AUTHOR]

Aims: In order to determine the effect of the characters, which are in high correlation with grain yield under contrasting conditions of growing, the nature of the interaction of the cultivar with the growing conditions was analyzed. Methods: Bulgarian wheat cultivars were investigated during four successive years at five locations within the country. The locations were chosen to cover the variety of soils and climate in all grain-production regions of Bulgaria. The complex interaction of the genotype with the environment was analyzed in relation to three characters - grain yield, and two characters (date to heading and number of grains per spike) with determining effect on it. Different statistical approaches were used to analyze the interaction of these characters with the environment and their effect on grain yield. Key results: The genotype x environment interaction was significantly high according to the factor year, as well as to the factor location of testing. The interaction year x location was low and insignificant. The variation determined in this experiment through principal component analysis reached third level, which complicated the assessment of the individual cultivars by two of the three investigated characters. Only with date to heading predominant linear interaction of the genotype with the environment was observed, which allowed determining of the cultivars' stability by this character. Conclusions: Grain yield can be correctly evaluated against the background of contrasting environmental conditions, through characters in positive correlation with it. In our case, these were the date to heading and the number of grains per spike. Each of the investigated characters revealed different nature and direction of the genotype's interaction with the environment. It is possible, through the established regularities, to objectively evaluate the cultivars which differ from the group mean. It is demonstrated how the stability of the grain yield is related to the stability of another two characters in the same cultivars. [ABSTRACT FROM AUTHOR]

Situation and aims. This investigation was carried out with the aim to determine the suitability of some Ukrainian wheat cultivars for improvement of the productivity of the Bulgarian ecotype of winter wheat. The economic traits and properties of promising breeding lines from crosses between them were studied. The focus was on the breeding possibilities of compromise combining early maturation with grain yield. Methods. A total of 50 genotypes were investigated: 40 of them were lines (from 4 hybrid combinations), 8 parental lines and several standard cultivars for comparison. Data were obtained from competitive varietal trials after growing for several successive years. The main traits directly or indirectly related to productivity were analyzed. The combination of earliness with the other economic traits and indices is discussed from the point of view of the combining ability of the early parents involved in the combinations. Key results. Although each studied combination involved an early parent, it was found that early forms were obtained with the participation of cultivars Obriy and Mironovskaya 29. The percent of early lines was highest in the combinations with their participation. In the crosses involving Albatros odeskiy and Mironovskaya 27, the productivity of the early lines was lower than the productivity of the parental lines. Cultivar Obriy was most promising for breeding work, especially for combining early heading with higher grain yield through high values of number of productive ears and grain size. Conclusions. Cultivars Albatros odeskiy and Obriy were most suitable for obtaining higher productivity in combination with earliness. The deriving of lines with earlier date to heading and higher productivity from the early cultivars Mironovskaya 29, Galateya and Enola was completely successful. By using specific cultivars, there is the possibility to combine high yield with earliness but within the limits of the specific parental cultivars for each individual combination. [ABSTRACT FROM AUTHOR]

Numerous common wheat varieties have been developed in Bulgaria, which when grown under variable environments, the magnitude of the grain yield is influenced by them. In order to determine the reasons for such variations the effect of the growing conditions on grain yield from the winter wheat cultivars with the highest distribution in production were investigated. The cultivars were investigated during four successive years at twelve different locations in Bulgaria with contrasting environmental components such as soil and climate. The phenotypic response of the cultivars was followed with a focus on the size of the yield and the direction of variation within the group of cultivars as a result of each factor: season, location of growing, genotype, and their complex interactions. The collected data were analyzed with the help of several well-known statistical software, (Statistica 7, Statgraphics XV, Jmp 10), which provided sufficient information on the genotype x environment interaction. Significant differences were found among the investigated cultivars by grain yield regardless of their specific response to the year conditions and the location. The genotype x environment interaction was significantly high and non-linear. This means that under changeable environments the different cultivars react differently and can therefore be grouped according to the grain yield stability and plasticity they demonstrated. This is very clear from the significantly high values of heterogeneity of variation. The principal component analysis showed that the dispersion of grain yield was of three-component type, PC1 being only about 1/3 of the total variation of the character, while PC2 and PC2 formed about 50 % from this variation. Within a wide ecological network of 12 locations in Bulgaria a significant genotype x environment interaction was established for grain yield in four successive years. The direct influence of the investigated factors, through their correlations with grain yield, showed the highest effect of the year (r=0. 476*), followed by the location (r=0.208*), the value of the genotype was the lowest and negative (r=-0. 194*). This normal distribution of the data on grain yield was combined with linear and non-linear type of interaction of the groups of cultivars with the year conditions, the location and their interaction as factors of influence; this made the analysis on the adaptability of each cultivar very difficult. [ABSTRACT FROM AUTHOR]

One of the main tasks of the contemporary breeding programs is developing of varieties characterized with high production potential and stability of grain yield under different growing environments. The aim of this investigation was to evaluate the yield stability of contemporary bread wheat cultivars grown in five successive years of contrasting meteorological conditions. The trial was carried out at DAI during 2007- 2011. The focus of investigation was on the grain yield from common winter wheat. The analysis of variances (ANOVA) undoubtedly revealed the significant interaction of the genotype with the environment The parameters of stability were calculated and the final evaluation of each cultivar included its grain yield according to the method of Kang (1998). Cultivars Zlatitsa and Korona realized the highest production potential during the investigated period. Relatively highest grain yield stability was demonstrated by cultivars Slaveya, Zlatitsa, Iveta, Aglika, Bolyarka and Dragana. Cultivars with high quality genetic potential such as Iveta, Lazarka and Aglika possessed excellent combination of high and stable grain yield significantly higher than the standard cultivar Pryaspa which belongs to third group of grain quality [ABSTRACT FROM AUTHOR]

Recurrent drought periods of varying duration often cause extensive crop damage and affect wheat production in Southern Europe. This study compares biochemical and ultrastructural responses of four wheat ( Triticum aestivum L.) cultivars to long-term field drought, and their contribution to final grain yield. Gel electrophoresis and immunoblotting analyses combined with transmission electron microscopy and grain yield evaluation were employed to assess drought susceptibility of the wheat cultivars. Two of them behaved as drought-tolerant, the other two presented as drought sensitive. Enhanced degradation of Rubisco large subunit (RLS), Rubisco small subunit (RSS) and Rubisco activase (RA) accompanied by an increased protease activity and reduced levels of heat shock proteins (HSP70) and dehydrins (DHNs) were associated with drought sensitivity. Drought tolerance coincided with relatively stable or increased HSP70 and DHN contents, and unchanged/higher levels of RLS, RSS and RA. Sensitive cultivars were more vulnerable to ultrastructural damages, showing obvious degradation of chloroplast membrane systems and depletion of leaf starch reserves. These drought responses affected yield potential, as tolerant cultivars gave higher yield under intense drought. Thus, our results provide additional insights into the complexity of plant drought responses, identifying multiple interacting traits that may serve as indirect selection criteria for wheat drought tolerance. [ABSTRACT FROM AUTHOR]