Water limitation is one of the major factors reducing crop productivity worldwide. In order to develop efficient breeding strategies to improve drought tolerance, accurate methods to identify when a plant reduces growth as a consequence of water deficit have yet to be established. In perennial ryegrass ( Lolium perenne L.), an important forage grass of the Poaceae family, leaf elongation is a key factor determining plant growth and hence forage yield. Although leaf elongation has been shown to be temperature-dependent under non-stress conditions, the impact of water limitation on leaf elongation in perennial ryegrass is poorly understood. We describe a method for quantifying tolerance to water deficit based on leaf elongation in relation to temperature and soil moisture in perennial ryegrass. With decreasing soil moisture, three growth response phases were identified: first, a “normal” phase where growth is mainly determined by temperature, second a “slow” phase where leaf elongation decreases proportionally to soil water potential and third an “arrest” phase where leaf growth terminates. A custom R function was able to quantify the points which demarcate these phases and can be used to describe the response of plants to water deficit. Applied to different perennial ryegrass genotypes, this function revealed significant genotypic variation in the response of leaf growth to temperature and soil moisture. Dynamic phenotyping of leaf elongation can be used as a tool to accurately quantify tolerance to water deficit in perennial ryegrass and to improve this trait by breeding. Moreover, the tools presented here are applicable to study the plant response to other stresses in species with linear, graminoid leaf morphology.

Drought is one of the critical abiotic stresses that significantly affect agricultural production, and current models predict an increase in its severity and intensity in the future. Generally, polyploidy has been found to improve the resistance of plants to abiotic stress. Understanding the role of ploidy in resistance to drought was achieved by comparing the response between diploids and their respective induced autotetraploids of Westerwolths ryegrass (Lolium multiflorum ssp. multiflorum). Field trials were carried out in the 2017 and 2018 growing seasons, and mild drought simulation experiments in controlled conditions were carried out to validate the effect of chromosome duplication. Results obtained from morphological traits in the field experiment revealed that the induced tetraploids were significantly (p < 0.05) taller, had longer inflorescences and larger flag leaf area than their diploid counterparts, especially in the year 2018 characterized by the prolonged drought. This study also revealed that the induced tetraploids produced more dry matter yield than their diploid progenitors, especially in drought periods. The induced tetraploids had significantly higher antiradical activity and phenolic content than the diploid progenitors in response to mild drought, and this significantly correlated with the plant performance in 2018 field trials, indicating that increased ploidy level plays an important role in conferring resistance to drought in Westerwolths ryegrass. Furthermore, the antiradical activity and total phenolic content proved to be a good tool to evaluate drought tolerance at the vegetative stage in Westerwolths ryegrass.

Winter hardiness is influenced by many environmental factors, and freezing tolerance is among the main ones, rendering the phenotypic selection of winter wheat (Triticum aestivum L.) under field conditions a difficult task due to the irregular occurrence or absence of winter damage in field trials. Plant growth in response to low temperatures during the acclimation period might be used as an indirect approach to assess freezing tolerance. Thirteen winter wheat cultivars were investigated for autumn and spring growth and winter hardiness under field conditions for two growing seasons. Additionally, a precise and non-destructive technique was applied to study leaf growth at a high temporal resolution accompanied by a freezing tolerance test under laboratory and semi-field conditions. The results of the study revealed variations in thermal growth patterns among the 13 winter wheat cultivars. The cultivars with the lower base temperature (Tb) values, in particular ‘Lakaja DS’ and ‘Sedula DS’, grew slower and, thus, had a lower response to temperature increases (SlpLER-T) than the fast-growing cultivars, such as ‘Simano” and ‘KWS Ferrum’, whose SlpLER-T values were stronger and whose Tb values were higher. A correlation analysis of the investigated traits showed a clear association between leaf growth parameters and freezing tolerance, indicating a certain level of genetic adaptation to growth cessation under low temperatures, and which confirmed that these are important factors for explaining the freezing tolerance of different cultivars. The evaluated freezing tolerance (LT30) showed a strong negative correlation (r = −0.82 ÷ −0.89, p = 0.01) to winter hardiness scores from the field experiment, supporting the essential contribution of growth rate patterns to winter hardiness. The findings provide novel information for the development of winter-hardy wheat cultivars that are adapted to the future environments.

Global warming is predicted to impact many agricultural areas, which will suffer from reduced water availability. Due to precipitation changes, mild summer droughts are expected to become more frequent, even in temperate regions. For perennial ryegrass (Lolium perenne L.), an important forage grass of the Poaceae family, leaf growth is a crucial factor determining biomass accumulation and hence forage yield. Although leaf elongation has been shown to be temperature-dependent under normal conditions, the genetic regulation of leaf growth under water deficit in perennial ryegrass is poorly understood. Herein, we evaluated the response to water deprivation in a diverse panel of perennial ryegrass genotypes, employing a high-precision phenotyping platform. The study revealed phenotypic variation for growth-related traits and significant (P &lt; 0.05) differences in leaf growth under normal conditions within the subgroups of turf and forage type cultivars. The phenotypic data was combined with genotypic variants identified using genotyping-by-sequencing to conduct a genome-wide association study (GWAS). Using GWAS, we identified DNA polymorphisms significantly associated with leaf growth reduction under water deprivation. These polymorphisms were adjacent to genes predicted to encode for phytochrome B and a MYB41 transcription factor. The result obtained in the present study will increase our understanding on the complex molecular mechanisms involved in plant growth under water deficit. Moreover, the single nucleotide polymorphism (SNP) markers identified will serve as a valuable resource in future breeding programs to select for enhanced biomass formation under mild summer drought conditions.

Two new waxy winter wheat (Triticum aestivum L.) cultivars, Eldija and Sarta, were developed at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry and released in Lithuania in 2021. The cultivars were developed using waxy wheat material from Nebraska, the United States of America. The mean yield of Eldija and Sarta at five locations over three testing years was 7.56 and 7.21 t/ha or 79.63 and 75.95%, respectively, compared to the yield of the standard cultivars. Eldija and Sarta should be grown under high input conditions due to the relatively low resistance to leaf spot diseases and Fusarium head blight and medium tolerance to lodging. An amylose content of 0.68% and 0.36% of Eldija and Sarta, respectively, a very low falling number (about 60 s), a lower flour yield and higher water absorption compared to common wheat and the reaction to iodine staining (brown colour) characterised the new cultivars as fully waxy wheats. These cultivars are intended for the potential demand from commercial companies for special use in the food industry.

Soil salinity is a global challenge emanating from climatic changes, depletion of fresh water reserves and extensive irrigation practices among other factors. Soil salinization still remains a huge concern in the realization of sustainable agricultural production. While emphasis has been placed on the food crops, forage production, which is an important component of the food chain, is affected as well. The aim of this study was to evaluate the morphological and physiological response to salinity stress in diploid cultivars and auto-induced tetraploid lines of annual ryegrass (Lolium multiflorum spp. multiflorum). Diploid seeds and their induced tetraploid counterparts were germinated on filter paper moistened with different concentrations of sodium chloride (NaCl) solutions, and seedlings were treated with 500 mM NaCl for 10 days in controlled conditions. The effect of different salt concentrations on germination and seedlings was studied. Results showed that seeds from the induced tetraploid lines despite being bigger had higher germination index and lower median germination time (T50) values compared to the diploid progenitors. At the seedling stage, increase in the ploidy level had a role in conferring improved tolerance to salinity stress. The induced tetraploid lines had an advantage over their diploid counterparts as the induced tetraploid lines had significant reduction in their growth in response to salinity stress, higher relative water content and antioxidant activities.

Abiotic stresses alter the expression of multiple genes in plants allowing them to accommodate to hostile environmental conditions. Exposure to low temperatures in the autumn prior to winter is a crucial environmental factor determining an increase in freezing tolerance and winter hardiness in temperate plants. The objective of this study was to evaluate transcriptome changes under a short-term low temperature stress using an RNA-Seq approach in winter wheat (Triticum aestivum L.). Significant alterations were observed for nuclear transcriptome of winter wheat, whereas the expression profiles of organellar genes were much less responsive to low temperature stress. In total, there were 15,042 nuclear genes with significantly (FDR < 0.05) altered expression profiles caused by exposure to low temperature. From this number, a total of 2,466 genes had a substantially (log 2 FC > 2 or log 2 FC < −2) affected expression profile. The highest number of upregulated genes was observed from chromosomes in homoeologous group 5, followed by group 2. Differentially expressed genes (DEGs) with the most extreme upregulation encompassed CBFIIId-12.1, WRKY transcription factor 55-like, and a group of genes related to jasmonate signalling pathway.

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