The assessment of diversity and population structure and construction of a core collection is beneficial for the efficient use and management of germplasm. A unique collection of common oat landraces, cultivated in the temperate climate of central Europe until the end of the twentieth century, is preserved in the Polish gene bank. It consists of 91 accessions that have never been used in breeding programs. In order to optimise the use of this genetic resource, we aimed to: (1) determine genetic and agro-morphological diversity, (2) identify internal genetic variation of the tested accessions, (3) form a core collection and (4) recognise the accessions useful for breeding programs or re-release for cultivation. The collection was screened using ISSR markers (1520 loci) and eight agro-morphological traits. Uniquely, we performed molecular studies based on 24 individuals of every accession instead of bulk samples. Therefore, assessment of the degree of diversity within each population and the identification of overlapping gene pools were possible. The observed internal diversity (Nei unbiased coefficient) was in the range of 0.17–0.31. Based on combined genetic and agro-morphological data, we established the core collection composed of 21 landraces. Due to valuable compositions of important traits, some accessions were also identified as useful for breeding programs. The population structure and principal coordinate analysis revealed two major clusters. Based on the previous results, the accessions classified within the smaller one were identified as obsolete varieties instead of landraces. Our results show that the oat landraces are, in general, resistant to local races of diseases, well adapted to local conditions and, in some cases, yielding at the level of modern varieties. Therefore, in situ conservation of the landraces in the near future may be satisfactory for both farmers and researchers in terms of the genetic resources preservation.

Here we focused on Polish oat landraces developed in the moderate temperature zone attempting to understand their genetic and phenotypic variability in context of the pressure of environmental constrains at the locations where they had evolved. Besides molecular markers and diverse phenotypic traits the Fourier transform infrared (FTIR) spectroscopy, enabling throughput metabolic fingerprinting, was used for the description of the germplasm collection. We used sophisticated multivariable analysis to integrate the data for structure analysis and to establish mutual relationships. We found that the accessions diversity across the eco-geographical variables was manifested differently depending on selected phenotypic, genetic, and metabolic criteria.Grain metabolic fingerprint derived from FTIR spectroscopy revealed the highest degree of germplasm diversity among all of the examined traits, particularly for spectral bands assigned to lipids. The landraces, which were collected in close geographical proximity, showed clear morphological and metabolic resemblances, although they represented quite different genetic backgrounds. All three levels of analysis showed the presence of selection resulting from environmental pressures and more specifically from the temperature at the landrace origin site. This research also proved that coupling of genetic polymorphism with the FTIR fingerprinting markedly extended the description of the oat landraces diversity.

Storage conditions have a strong influence on the germination of seeds of <em>Avena fatua</em> L, especially at variable conditions, the germination decreased. Seeds stored at a constant low temperature maintained the germination capability for 5 years. Under greenhouse conditions, seeds matured and germinated more rapidly comparing to field conditions, but individuals from these seeds were weaker and produced fewer seeds. The higher temperature in the greenhouse accelerated the development and maturing of plants. Field emergence varied depending on seed storage conditions, sample, further reproduction, and weather conditions. It was observed that individual specimens of <em>A. fatua</em> were able to form ripe seeds with high thousand grain mass (TGM), regardless of the occurrence of fungal diseases. The knowledge of the biology of <em>A. fatua</em> is very important due to its status as a restricted weed in certified seed of crop plants.