Landraces of wheat (Triticum aestivum L.), collected from the Western Balkans, were considered as a potential genetic resource of drought resistance for wheat breeding. A group of 20 landraces with 80 wheat accessions of worldwide origin were tested in 4-year field trials under two watering regimes: fully irrigated and under a rain-out plot shelter. Fourteen agronomic traits were evaluated for their responses to drought stress, and four selection indices were calculated: mean productivity (MP), stress tolerance (TOL), stress susceptibility index (SSI) and stress tolerance index (STI). The average yield of landraces was significantly lower than that of accessions under both regimes, and there was no evidence that yield stability of landraces was better than that of accessions. However, TOL was better in landraces than in accessions, and several traits related to yield were shown to suffer less under water deficit (i.e. kernels per spike). Amongst landraces, relatively wide diversity (CV 10.2-18.9%) was found for most of the traits that can be exploited for improving drought tolerance of new varieties for the variable rainfed conditions of south-eastern Europe.

Wheat cultivars grown in south-eastern Europe are exposed to variable rainfed environments. Climate change predictions indicate that the frequency of dry years will likely increase in the future. This study examined relationships among agronomic traits and some drought indices with grain yield as influenced by genotype and environment. In a 4-year experiment, 100 cultivars and landraces of bread wheat (Triticum aestivum L.) from different countries were tested under 3 watering regimes: fully irrigated, rainfed, and in a rain-out plot shelter. Three selection indices, mean productivity (MP), tolerance (TOL), and stress susceptibility index (SSI), were calculated based on grain yield in irrigated and drought-stressed conditions. The additive main effects and multiplicative interaction (AMMI) models were used to study the genotype × environment effects. Average yield reduction due to drought in the sheltered plots was 37.5%. High-yielding genotypes in each treatment showed high values of MP and high rank for SSI and, particularly, TOL. Conversely, low-yielding genotypes in each treatment had low values of MP and high drought tolerance according to SSI and TOL (i.e. low ranks). MP values were noted as being particularly well suited for predicting performance in this experiment. Total biomass and early vigour were found to be the most important agronomic traits for selecting high-yielding genotypes in a range of stress and non-stress conditions.

This study was conducted to assess drought tolerance and regional-based patterns of diversity of bread wheat accessions and to identify new sources of diversity that could accelerate the development of improved wheat varieties better suited to meeting the challenges posed by changing climate in Southern and Eastern Europe. For this, genetic diversity assessed by simple sequence repeats (SSR) markers was compared with diversity evaluated using 19 phenotypic traits averaged over irrigated and drought-stress field conditions. Thirty-six SSR were used to profile 96 wheat genotypes from the collection of genetic resources at the Institute of Field and Vegetable Crops, Novi Sad, Serbia. A total of 46 loci and 366 alleles were detected, with a range of 3–21 alleles per locus. The polymorphic information content was estimated to be 0.61. The genetic distance for all possible 4560 pairs of genotypes ranged from 0.06 to 0.91 with an average of 0.65. Genotypes were grouped according to their drought tolerance (high, medium, low) and region of origin. Analysis of molecular variance showed that over 96% of the total variation could be explained by the variance within the drought tolerance and geographical groups. As a whole, genetic diversity among the high drought tolerance genotypes was considerably higher than that among low drought tolerance genotypes. Comparative analysis of SSR diversity among six regional groups revealed that the genotypes from North America exhibited more genetic diversity than those from other regions. Two dendrograms were constructed based on phenotypic and molecular analyses using the Unweighted Pair Group Method with Arithmetic Mean method and were found to be topologically different. Genotypes characterised as highly drought tolerant were distributed among all SSR-based cluster groups. This implied that the genetic basis of drought tolerance in these genotypes was different, thereby enabling wheat breeders to combine these diverse sources of genetic variability to improve drought tolerance in their breeding programs.

Improving resistance to water and osmotic stresses at the seedling stage is becoming a much more important target for wheat breeders due to an increase in the frequency and severity of drought occurrences at the crop establishment and tillering phases in many wheat growing areas of the world. Ninety-six diverse wheat genotypes were laboratory tested for germination and growth response under osmotic stress induced by polyethylene glycol (PEG). Germination percentage, mean germination time, coleoptile length, shoot length and shoot growth rate were compared under stress (− 0·4 MPa) and control (0·0 MPa) conditions. The same genotypes were previously grown in field trials exposed to drought stress during the anthesis and/or grain filling growth stage along with control (optimum) conditions. Grain yield (GY) and 19 other traits of agronomic importance (earliness, stemrelated traits, number of kernels, mass of 1000 grains, etc.) were recorded. All seedling traits under PEG-induced water stress showed the highest relationship with the stem and stem-related traits of adult plants. To study the correlation between stress tolerance in the seedling and reproductive stages, three stress indices (tolerance index (TOL), stress susceptibility index (SSI) and stress tolerance index (STI)) for the seedling traits and GY under pre-and post-anthesis drought stress were calculated, based on a mean trait value obtained under stress and the corresponding trait value under control conditions. The ranking of the genotypes based on TOL and STI from seedling traits was found in most cases to be significantly correlated with the ranking of genotypes based on TOL and STI from GY, respectively.