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General-Toshevo, Bulgaria

Yankov P.,Dobrudzha Agricultural Institute
Bulgarian Journal of Agricultural Science | Year: 2010

The investigation was carried out during 2003-2006 in the trial field of Dobrudzha Agricultural Institute on slightly leached chernozem soil type. A stationary field trial initiated in 1987 has been investigating 24 soil tillage systems based on different soil tillage tools and operations. The following field crops have been involved in 6-field crop rotation: wheat, grain maize, bean and sunflower. The following variants of main soil tillage were used in this analysis: ploughing at 24-26 cm, disking in autumn and double cultivation in spring (check variant); cutting at 24-26 cm, disking in autumn and double cultivation in spring; double disking at 10-12 cm accompanied by autumn disking and double spring cultivation; direct sowing - pre-sowing treatment of field with total herbicide. With the reduction of the number and depth of the soil tillage operations in bean, the number of pods per plant, number of seeds per pod, 1000 seed weight per plant and 1000 seed weight decreased. Replacing deep ploughing with plowless tillage, with shallow and no tillage lead to a significant decrease of seed yield from bean variety Abritus from 4.3 to 16.5 %. Source

Ganeva G.,Bulgarian Academy of Science | Petrova T.,Dobrudzha Agricultural Institute | Landjeva S.,Bulgarian Academy of Science | Todorovska E.,AgroBioInstitute | And 4 more authors.
Biologia Plantarum | Year: 2013

Frost tolerance of ten Bulgarian winter wheat (Triticum aestivum L.) cultivars (Milena, Pobeda, Sadovo-1, Enola, Kristal, Laska, Svilena, Russalka, No301 and Lozen) and five foreign cultivars (Mironovskaya 808, Bezostaya-1, Rannaya-12, Skorospelka-35 and Chinese Spring) was studied in two experimental seasons following natural cold acclimation and in one experiment carried out in controlled acclimation conditions. Considerable intercultivar variability in plant survival was observed after freezing at -21 °C following sufficient cold acclimation, or at -18 °C following insufficient or controlled acclimation. In seven cultivars, the effects of chromosome 5A on frost tolerance were investigated in their F2 hybrids with chromosome 5A monosomic lines of cultivars with high, intermediate and low frost tolerance. The effects of chromosome 5A depended on the stress severity and the genetic background of the hybrids and varied even in cultivars of similar frost tolerance and vernalization requirements. Effects of other chromosomes besides 5A on frost tolerance were assumed. The analysis of six microsatellite loci located in the interval from centromere to Vrn-1 on of chromosomes 5AL, 5BL and 5DL showed that the major loci determining frost tolerance in Bulgarian winter wheats were Fr-A2 on chromosome 5AL, and, to a lesser extent, Fr-B1 on chromosome 5BL. A strong association of the 176 bp allele at locus wmc327 tightly linked to Fr-A2 with the elevated frost tolerance of cvs. Milena, Pobeda, Sadovo-1, Mironovskaya-808 and Bezostaya-1 was revealed. Relatively weaker association between frost tolerance and the presence of the 172 bp allele at locus Xgwm639 tightly linked to Fr-B1 was also observed. © 2012 Springer Science+Business Media B.V. Source

Ivanova A.,Dobrudzha Agricultural Institute | Tsenov N.,Dobrudzha Agricultural Institute
Bulgarian Journal of Agricultural Science | Year: 2011

The aim of the investigation was to determine the productivity of common wheat genotypes under contrasting environments. The investigated wheat cultivars were grown in two successive years: 2006, which was very favorable for wheat cultivation, and 2007, when one of the most severe and long-lasting droughts in Bulgaria was registered. The genotypes were grown in a complex scheme involving four previous crops and three levels of mineral fertilization, according to the type of previous crop. Grain yield and the following productivity components were studied: 1000 kernel weight, test weight, number of productive tillers, plant height, number and weight of grains per spike. The correlation of grain yield with the related traits was analyzed under contrasting environments. It was found out that the drought in 2007 caused about 30 % decrease of the productivity of the investigated common wheat genotypes. The reduction of grain yield was due to the lower weight of grains per spike (about 40%), the lower number of grains per spike (about 29%) and the smaller size of grains (about 15%). The independent effects of the genotype and the mineral fertilization were much better expressed on the studied traits under the favorable conditions of 2006, and the type of previous crop had significant effect under drought. The relation of grain yield with the number of productive tillers, plant height, weight and number of grains per spike was higher under stress during the growth period of the crop. Source

Tsenov N.,Dobrudzha Agricultural Institute | Tsenova E.,Dobrudzha Agricultural Institute
Bulgarian Journal of Agricultural Science | Year: 2011

This investigation was carried out with a view of evaluating the combining ability and the heritability regularities of a group of wheat cultivars which differed significantly by their date to heading (DH) and date to physiological maturity (DPM). Six common winter wheat cultivars were combined in a complete diallele crossing scheme. The two traits were represented as number of days from 1 st January to the respective date for each of them. During three successive years, the early F 1 and F 2 hybrid generations were analyzed. They were grown in a randomized design, the distance between the rows being 20 cm and the distance between the plants in each row - 10 cm. Each cultivar was evaluated for combining ability and the breeding value of each combination was assessed for the above two traits. The combining ability and the genetic parameters were calculated using the program Dial 98. Lack of reciprocal effect was established although the mother component strongly affected the phenotypic expression of the two traits. There were significant variations between the investigated cultivars in the expression of the two traits within 5-7 days. The values of GCA were predominant as a rule over the values of SCA in the variation analysis performed on the entire crossing scheme. This was evidence for some dominance of the genes with additive effect of the factors determining the two traits. GCA of each cultivar was directly related to the expression of the two traits, the correlation being as high as 0.95. The heritability of the two traits was analogous and resulted from complex combinations of genes with different effects (additive or dominant). The higher the difference between the parental cultivars in a combination by the two traits, the higher the inherited DH and DPM values were. The regularities in the genetic control and the combining ability of the investigated cultivars by DH were completely analogous for the trait DPM, as well. This means that earliness could be easily evaluated by DH. Cultivars Pliska, Vratsa and Obriy had high combining ability towards earlier dates to heading and maturity. Cultivar Pryaspa had the latest dates in the diallele crossing scheme, but its breeding value implied successful breeding of earliness in combination with high productivity. Source

Tsenov N.,Dobrudzha Agricultural Institute | Atanasova D.,Dobrudzha Agricultural Institute
Bulgarian Journal of Agricultural Science | Year: 2015

Aims: The large number of wheat cultivars developed in Bulgaria requires evaluation of yield variation in the grain production regions of Bulgaria. The analysis on the interaction of the cultivar with the growing conditions was used to make a specific evaluation of each cultivar for its ecological plasticity and stability.Methods: Cultivars grown in the farmers’ fields were selected and tested for three consecutive years at eight locations in Bulgaria, which were representative for the entire territory of the country and had contrasting soil and climatic conditions for crop growing. Multiple statistical methods and approaches were applied to evaluate the adaptability of each cultivar by grain yield against the background of the complex genotype x environment interaction. A number of parameters and indices were calculated using several types of software (STABLE, GEST98, GGE biplot 6.5, JMP 10) to find out the variation and correlations among the cultivars.Key results: Significant variations of grain yield were found among the investigated cultivars regardless of their specific response to the year conditions and the location. The interaction genotype x environments was significant and high, and was of non-linear type. The changeable environmental conditions caused different reactions of the cultivars, which allowed dividing them into groups according to the plasticity and stability they demonstrated. The variation in this experiment determined through principal component analysis reached level four, which is comparatively rare for this trait. On the whole, PC1 had low value (49%), while PC2 was high (16%). There were several cultivars with very high PC2 values, exceeding several times the values of their respective PC1.Conclusions: The percent of variation caused by the environment was significant for grain yield under the conditions of Bulgaria. The investigated cultivars differed not only by grain yield but also by their plasticity and stability under changeable environments, the percent of the genotype effect being about 12% for the entire experiment. It was found that each cultivar can give high grain yield at high ecological stability regardless of its genetic potential for quality. Best balance between grain yield and stability was found in cultivars Aglika, Demetra, Iveta (first quality group), Galateya, Slaveya (second quality group) and Todora, Kristal and Pryaspa (third quality group). Cultivars Sadovo 1 and Pobeda were most affected by the environment, which was not a typical behavior of cultivars used as checks. © 2015, National Centre for Agrarian Sciences. All rights reserved. Source

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