Monoculture of modern cereal crops are popular due to the technical and organizationa lreasons. They are easier in crop husbandry, qua lity and product use. However, in monoculture chemical protection of crops is a norm, due to the fact that they are more susceptible to diseases, pests and sometimes weed infestation. In order to keep high and stable grain yields and quality in monoculture one has to use high inputs. Experimentally and practically it has been proved that cultivar and species mixtures can constitute an alternative to cultivar growing in pure stands. It has been found that in mixtures opperate different epidemiological and ecological factors, which lead to considerable disease reduction, pest and weed control, which finally result in higher and more stable grain yields than in barley varietes grown in pure stands. The results of two years field experiment designed to evaluate epidemiological and economical effects of winter barley cultivar mixtures are presented. The studies were carried out in two sites – experimental lStation for Variety Testing Słupia Wielka (in Wielkopolska region) and Plant Breeding Station Bąków (Opole District). This two sites were 300 km away from each other, and had different soi land meteorological conditions. In the experiment impact of different barley cultivars and their different two- and three-component mixtures were tested with reduced dosages of fungicidies on grain yield in the mixtures compared with pure stands were evaluated.

In the experiment the population dynamics as well as the development of Myzocallis caryli on five hazel cultivars were investigated. In terms of host plant resistance to Myzocallis caryli the tested cultivars displayed very similar susceptibility. The obtained results show that no significant differences were found in aphid rm. In spite of this, due to the longest prereproductive time, the lowest fecundity and the smallest number of aphids per 10 leaves, Kataloński is less suitable cultivar for the aphids from all tested hazel cultivars.

In 1999-2001 the occurrence of thrips was analysed on seven cultivars of pea. The samples of leaves, then leaves and flower buds and the flowers were collected from plots. The analyses were initiated when the earliest cultivar (Sześciotygodniowy) began flowering and were repeated every 4-7 days, until the end of flowering. The following species of th rips were found: Franklinie/la intonsa Trybom, Thrips major Uzel, Thrips fuscipennis Hal., Thrips tabaci Lind. and Kakothrips robustus Uzel. The clear differences between the number of thrips on the particular cul tivars of pea were noticed. The most attractive were late cultivars Nike and Telefon as well as middle late Delisa II. It seems that the most important factor effecting on the number of thrips on particular cultivars was rather the start and the end of flowering than the length of the flowering period. The greatest number of thrips was noticed on flowers, from 50% to 77%. The thrips initially were found on leaves and then, as the pea was growing, on the flower buds and flowers. After the emergence of thrips, the analyses should be first initiated on leaves.

Phytophthora citricoia dominated among 11 genera and fungal species isolated from Rhododendron brachycarpum, R. catawbiense, R. impeditum and R. sepedonicum. In greenhouse trial isolates from Abies concolor, Chamaecyparis lawsoniana, R. catawbiense, R. impeditum and Thuya occidentalis caused dieback of rhododendron. Inoculation of leaf blades with isolates of the pathogen from 4 cultivars resulted in the spread of necrosis about 0.63 mm/hr. P. citricola was pathogenic to all tested rhododendron cultivars.

Gene postulation is one of the fastest and most cost-effective methods for identifying seedling leaf rust resistance genes in wheat cultivars. Many researchers use this approach to identify Lr genes in wheat cultivars. The purpose of our research was to identify seedling leaf rust resistance genes in 20 wheat cultivars from different breeding centers of Russia, Ukraine and Germany. Forty-two near isogenic Thatcher lines and 10 Puccinia triticina isolates were used for gene postulation. When assessing the infection types to cultivars and lines, a scale was used, according to Oelke and Kolmer. In 20 wheat cultivars 19 Lr genes were postulated: 2c, 3, 10, 3bg, 3ka, 14a, 17, 18, 23, 25, 26, 30, 33, 40, 44, 50, B, Exch, Kanred. The most common for cultivars was the Lr10 gene. In five cultivars, showing high field resistance, most postulated seedling genes (Lr2c, Lr3, Lr10, Lr14а, Lr26, Lr33) were not effective in the adult stage. It is possible that resistance of such cultivars is associated with APR genes, the postulation of which requires an expansion in the number and spectrum of P. triticina isolate virulence. Most of the studied cultivars (60%) have recently been entered into the register (2015–2019) and in the field show a stable or moderately susceptible response to P. triticina infection, despite the fact that the Lr genes postulated in them were not effective in the adult stage. The data obtained indicated a variety of genotypes of the studied cultivars, as well as the tendency of breeders to use the effect of pyramiding ineffective genes, which can prolong the resistance of the cultivar. Annual monitoring of varieties is necessary in each region, especially when reacting with a medium susceptible type (MS), which may indicate the initial stage of resistance loss.

An application of biostimulants is becoming an increasingly popular operation in agriculture because they positively affect crop performance and qualitative characteristics, and prevent stress-related losses. The objective of this study was to determine the effect of an application of the following biostimulants: PlonoStart, Aminoplant, and Agro-Sorb Folium, and the herbicide Avatar 293 ZC on total carotenoids in table potato tubers. The research material consisted of tubers of two table potato cultivars, Oberon and Malaga, which were produced in a 3-year field experiment. Chemical analyses of fresh material were conducted 4–6 days following harvest. Biostimulants applied with the herbicide significantly increased the table potato tuber content of carotenoids compared to tubers obtained from unamended control plots. The highest accumulation of carotenoids was determined following an application of the biostimulant Agro-Sorb Folium, and it was higher in the tubers of cv. Oberon versus cv. Malaga. It should be added that in the available literature there is no research on the effect of biostimulants on the content of carotenoids in potato, which is the main food in the world. Carotenoids perform many important functions in the human body. They exhibit antioxidant properties, which means that they protect cells from damage, and also have a beneficial effect on the immune system. Carotenoids are substances that show an indispensable effect on the health and appearance of the skin. Regular consumption of them in the form of vegetables and fruits ensures its firmness, elasticity, smoothness, as well as a healthy appearance. The protective function of carotenoids against free radicals simultaneously contributes to slowing down the aging process. This action, in turn, translates into preventing the development of cancer or diseases of the circulatory system.

Soybean ( Glycine max (L.) Merrill.) yielding potential depends on environmental conditions (precipitation, temperature, soil). The aim of the work was to evaluate stability of yielding (and other traits) of three soybean cultivars (Abelina, SG Anser, Merlin) grown under the climatic conditions of central-eastern Poland. The studied material was obtain in a field experiment conducted at Łączka (52°15' N, 21°95' E) during the growing seasons of 2017–2019. Trait stability was determined based on Shukla’s genotype stability variance and Wricke’s ecovalence describing the genotype-by-environment interaction. For all the examined parameters, there were found significant differences between successive growing seasons, cultivars, and cultivars within study years. The greatest influence of environmental conditions (years) was determined for plant height (64%) and first pod height (54.2%). Stability parameters indicated that cv. Abelina was the most stable in terms of yielding, 1000 seed weight, seed number per pod and average seed number per pod, cv. SG Anser being the least stable in this respect

Clarifying the genetic background of the drought-tolerance trait is a crucial task that may help to improve plant performance under stress by a genetic engineering approach. Dehydration-responsive element-binding protein (DREB) is a transcription factor family which modulates many stress-responsive genes. In this study, we isolated a DREB homolog gene named ZmDREBtv from Zea mays var. Tevang-1. Using bioinformatic tools, a number of InDels and SNPs in ZmDREBtv sequence different from the reference accession were identified. In addition, based on deduced protein sequence similarity, ZmDREBtv was assigned to transcription factor DREB2 class as featured by a conserved DNA binding domain - AP2. The ZmDREBtv construct under thecontrol of the rd29A promoter was transformed into a drought-sensitive maize plant, K7 line. The transgenic plants were assessed with reference to molecular and phenotypic characteristics related to the drought-tolenrance trait. The results proved that the maize plants carrying ZmDREBtv gene showed enhanced tolerance and better performance to the water-deficit environment at different stages, compared to the wild-type plants.