Abstract. 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

Dobrudzha Agricultural Institute One of the main directions of the breeding programs in common winter wheat, besides increasing productivity, is developing of cultivars with excellent baking properties. An important prerequisite for this is the involvement of new gene plasma of variable origin, which is adequate to the growing conditions and the desired breeding direction. The aim of investigation is study of some main properties related to the grain quality and the baking properties of bread wheat accessions of foreign origin under the conditions of the South Dobrudzha region. Twenty-five foreign bread wheat cultivars of various origins were investigated for a three year period. Cultivars Aglika, Enola, Pryaspa and Yantur were used as standards. Some indices related to the quality of grain and flour were analyzed at the Bread Making Laboratory of (DAI). The expression of the following parameters was followed: test weigh, % of protein, sedimentation, wet gluten yield, softening degree, pharinographic value, bread volume, and the quality index (QI) was calculated. The cultivars, which demonstrated high grain quality, were the Romanian Faur, Moldovan Dobropolka, American Wahoo and the Ukrainian Zmina. Averaged for the three years, highest variation was found for the index pharinographic value. On the whole, the materials with origin from Romania, Ukraine and USA were characterized with high values of the quality indices. Cultivars Faur and Zmina can be successfully included in the breeding program of DAI for development of strong wheat varieties.

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Data from the Multi Environmental Field Trail (MET), which examined 24 varieties of common wheat, were divided into three "datasets" related to three of the five study locations. Using meta-analysis, these three data sets were compared with those from the whole experiment. The aim of the study is to determine whether a 4-year growing period in three country-specific locations, it is possible to establish a significant impact of the environment on the stability of a group of varieties. The analysis of the genotype x environment interaction (GEI) was performed in parallel in the three groups of data, which were compared with the entire MET database. A direct comparison was made on them regarding the possibilities of non-parametric methods to assess the stability of the variety. The analysis of the results of the four "datasets" is done through a number of statistical approaches, allowing them to be correctly compared at different levels. Genotype x environment interaction was found in each of the studied locations. The variation in yield in them is a result of the direct effect of the "year" and the combined effect of the genotype x year. At all three locations, the GEI is broken down into four main components, which is evidence of the strong linear and non-linear nature of the dispersion of grain yield. These results are a prerequisite for an objective assessment of genotype stability. All applied parameters give completely similar stability information for each of them, regardless of the test location. Data from one location are sufficient to assess the stability of each variety in a group. This may be the case if significant differences between the seasons of the trial, are found. The applied non-parametric methods for stability assessment give correct information about the varieties, in the presence of GEI, regardless of the conditions from which the data for analysis are selected.

The genotype specificity in the uptake of the main nutrients according to the fertilization rate was investigated in Triticum aestivum L. varieties under conditions of a vegetation experiment. Four fertilization rates were tested: N 0 P 0 K 0 , N 200 P 200 K 200 , N 400 P 200 K 200 and N 600 P 200 K 200 . The response of the varieties to the nutrition conditions provided was studied during several stages of growth and development. The different nutrition regimes used lead to manifestation of the specific abilities of the varieties to take up nutrients. Genotype and mineral fertilization had a higher effect on nutrients uptake than stage of development. During the initial stage of wheat development, the differences established in the uptake of macro elements were greater between the varieties than between the individual fertilization rates. The differences were most evident at maturation. This specificity was well expressed in nitrogen and phosphorus uptake in total biomass and to a lesser extends -in potassium uptake. Varieties Slaveya and Milena had highest amounts of nitrogen uptake in grain.