The aim of the present work was to compare the drought tolerance of three new Bulgarian common winter wheat varieties (Sashez, Ginra and Gizda) with one older variety Fermer, that is sensitive to drought stress. The sensitivity of investigated varieties to 3 and 7 days dehydration and their ability to recover after a period of 3 days re-watering were evaluated by following the alterations in the leaf pigment content, lipid peroxidation (MDA), generation of reactive oxygen species (H2O2) and levels of protective substances (anthocyanins). Results revealed that varieties Ginra and Gizda were the most resistant to applied dehydration, Sashez had medium resistance, while Fermer showed high sensitivity to water deprivation. Variety Sashez responded to 7 days of water deprivation with a significant increase of lipid peroxidation, but after re-watering for 3 days recovered successfully. After 3 days of dehydration, the level of protective anthocyanins was enhanced in Sashez, Ginra and Gizda, while during the whole experimental setup their level was very low in Fermer. Data demonstrated as well that the dehydration-induced lipid peroxidation and levels of H2O2 were highest in variety Fermer. The photosynthetic pigments were decreased after 7 days dehydration in all varieties, except in Ginra, and recovered after rewatering. The results obtained in respect to drought resistance and ability to recover after the stress of the investigated wheat varieties will be of interest to breeders for the development of new high-yielding drought tolerant wheat and achievement of sustainable agriculture in water-limited environments.

The study was conducted during the period 2017-2019 in the experimental field of IPGR Sadovo. Wheat is the most important agricultural crop worldwide. Bulgarian wheat production in 2019 amounts to 6.162 thousand tons - an increase of 5.7% compared to 2018, due to the relatively favorable climatic conditions in the process of crop development, which led to an increase in average yield (with 6.8%). Twenty nine common winter wheat varieties (Triticum aestivum L.) with Belorusian origin and two Bulgarian varieties - Sadovo 1 and Enola were evaluated. The studied materials were sown in 2 rows with the length - 2 m, at the row spacing - 20 cm and the distance in rows - 5 cm. The standard technology adopted in IPGR for cultivation of common winter wheat was used. The aim of this study is to investigate the genetic distance of common winter wheat genotypes with a view to their use in the breeding process as sources of initial material for the formation of new and highly productive wheat varieties. Biometric measurements were made on 20 plants of each genotype and the main productivity indicators were recorded. To evaluate the genetic similarity between the different varieties, cluster analysis and PC analysis were applied. Based on the cluster analysis, the studied genotypes are classified into five large cluster groups. With the most genetic closeness to each other are characterized the varieties Vasilisa and Uzlet, followed by Daria and Rostan. The greatest genetic distance is shown between the Bulgarian varieties Sadovo 1 and Enola to the varieties from Belarus. The greatest genetic difference was found between Sadovo 1 and Rassvet, followed by Enola and Rassvet. Genetically distant varieties belonging to different cluster groups can be used as sources of initial material to achieve genetic diversity in the breeding of common winter wheat.

No abstract

Serious economic damages in many regions of the world were caused by the changes in agroclimatic resources during the last 2–3 decades. The Balkan Peninsula is much affected by the temperatures rising, changes in the distribution of precipitation, and the increasing frequency of extreme events—basically, droughts and frosts. Bulgarian agriculture is developed under various agrometeorological conditions. The climate of the country is characterized by the atmosphere and soil moisture deficit in the time of active crop vegetation and yield formation. The aim of this research is to assess the changes in agrometeorological conditions for the growth of the main grain crops and the possibilities for reaction through agro-technologies. Furthermore, the features of contemporary varieties and hybrids of spring and autumn cereals will be taken into account. The next important factor is the specific requirements for hydro-thermal conditions at different phenological phases of agricultural crop development, i.e., sums of the temperatures and precipitations. Agro-technologies react to tendencies in changing agrometeorological conditions. For the adaptation of agro-technologies, the maximum use of natural agroclimatic resources should be included in activities for overcoming unfavorable conditions, as well as the increased frequency of extreme events. A detailed assessment of the agrometeorological conditions is necessary to choose the suitable agro-technology activity. The analysis of the main meteorological elements—temperatures, precipitations, air humidity, wind speed, and solar radiation for thirty years (1986–2015) was used to assess the changes in agrometeorological conditions on agricultural lands in Bulgaria. Appropriate agro-technical activities for growing the main grain crops are proposed in accordance with the observed changes.

In the course of our study on the adaptation of modern genotypes common winter wheat (Triticum aestivum) to the requirements of sustainable agriculture data were received concerning the influence of the predecessor and nitrogen fertilizer rate on energy efficiency and recyclable nitrogen fertilization and profitability of productivity.We share these data with the scientific community, as they are up-to-date and informative in both theoretical and practical aspects. The analyses are based on data from field experiments fertilizer derived after predecessor cereals-regular crop of sorghum, millet, maize and legumes after predecessor-separate sowing of chickpeas. Energy efficiency of nitrogen fertilization was calculated as the ratio between the energy supplied in the additional grain yield and energy input in the form of fertilizers. Refundable efficiency of nitrogen fertilization is the additional amount of nitrogen accumulated in the grain, with respect to the applied nitrogen fertilization. Economic profitability of production is evaluated by coefficient R = P/Ra (ratio of benefits/costs). The results show that energy efficiency and recyclable nitrogen fertilization are on average five times higher after cereal than after legumes predecessor, and decreased with increasing the fertilizer rate, the decrease was statistically significant only for the first item (exponent). Profitability ratio of production after the introduction of legumes predecessor in crop rotation increases by an average of 42% and retains maximum values of fertilization levels 0.06, 0.12 and 0.18 t/ha nitrogen. Profitability of wheat production using pre-legumes crop is not determined by the parameters nitrogen fertilizer rate and energy efficiency of nitrogen fertilization and refundable efficiency of nitrogen fertilization.