EFFECT OF THE MORPHOLOGICAL TRAITS ON SEED YIELD OF LUCERNE BREEDING POPULATIONS IN LITHUANIA

Phenotypic correlation coefficients between seed yield and morphological traits of lucerne (Medicago sativa L.) breeding populations were determined. Ranking of populations by seed yield and subsequent calculating of correlations showed that as higher differences in seed yield among populations was as higher correlations were obtained. Among the characters examined seed yield was positively correlated with the length of raceme, number of flowers, pods and seeds per raceme, number of seeds per pod (r=0.31*, 0.61*, 0.42*, 0.57*, 0.53*, respectively). Negative relationships were determined between spring regrowth height, alfalfa mosaic, flowering period, plant regrowth height after harvest, 1000 seed weight and seed yield (r= -0.42*, -0.81**, -0.64*, -0.71*, -0.41*, respectively)

Relationships among alfalfa resistance to Sclerotinia crown and stem rot, Sclerotinia trifoliorum and oxalic acid

Sclerotinia crown and stem rot (SCSR) of alfalfa caused by Sclerotinia trifoliorum is one of the main constraints for efficient alfalfa cultivation in temperate climate all over the world. The resistance of 200 alfalfa accessions to Sclerotinia crown and stem rot was evaluated during 2010 to 2011 in the field nursery established in 2009. The resistance of alfalfa accessions germinating seeds to mycelium of Sclerotinia trifoliorum and oxalic acid (OA) concentrations of 10, 20, 30 mM was screened under laboratory conditions. The statistically significant differences at P<0.05 were determined among evaluated alfalfa accessions resistance to all screened factors. The reactions of alfalfa accessions to disease under field conditions showed that majority of the non-adapted accessions were heavily diseased, whereas the resistant accessions had only negligible disease severity. The germination of accessions seeds at oxalic acid concentration of 30 mM showed strong correlation (r = -0.817**, P<0.01) with SCSR severity in 2011. Among OA concentrations, this one showed the highest correlation rate with SCSR as well as was the least time consuming method. This method of seeds germination on mycelium of S. trifoliorum was unfit due to its weak correlation with SCSR and higher inputs.Keywords: Alfalfa, resistance screening, Sclerotinia trifoliorum, oxalic aci

Coleoptile length and plant height of modern tall and semi-dwarf European winter wheat varieties

A total of 124 recent winter wheat accessions of European origin were screened for coleoptile length and plant height. Most of the accessions (74.2%) possessed a coleoptile length ranging between 5.00 and 7.00 cm. The German varieties Ebi, Pegassos, Flair without Rht genes had a coleoptile length of 9.08, 9.43, 9.56 cm and a plant height of 97, 95 and 98 cm, respectively. The Serbian variety Pobeda possessing Rht8 had a coleoptile length of 9.14 cm and a plant height of 71 cm. The varieties possessing Rht-B1b, Rht-D1b had a significantly shorter mean coleoptile length (5.45 cm) and mean plant height (84.5 cm) than the varieties without Rht genes (7.41 and 99.6 cm). The correlation between coleoptile length and plant height was medium (r = 0.613, p < 0.01) when the calculation excluded the varieties from Central and Southern Europe. The similar plant height, but not coleoptile length of the varieties possessing different dwarfing factors enables development of novel varieties with desirable height and coleoptile length from the European winter wheat germplasm

Impact of Combined Drought and Heat Stress and Nitrogen on Winter Wheat Productivity and End-Use Quality

Water deficit and heat stress are the main abiotic stresses affecting the yield and quality of winter wheat. The increasing frequency of the simultaneous occurrence of these two stresses might threaten global food security and drives the need to breed resilient high-quality cultivars. The aim of this study was to evaluate the grain yield, quality and gluten protein characteristics in 50 winter wheat cultivars and breeding lines during the harvest years of 2018 and 2019. The yield and grain quality components were affected more severely by the combined heat and drought in 2019 than the drought in 2018. Two nitrogen (N) fertilization regimes were studied, sustainable (S, 15/100/30 kg N ha(-1)) and high-input (HI, 15/100/100 kg N ha(-1)). The yield was higher in HI trials compared to S trials by 2.2 t ha(-1) in 2018 and by 2.4 t ha(-1) in 2019. Higher protein content and sedimentation volume and lower yield, test weight and starch content were observed under combined heat and drought stress in 2019 compared to 2018. Genotypes containing the Glu-D1 x5-y10 allele exhibited the higher amounts of unextractable polymeric proteins (%UPP = 58.5%) in gluten studied by size exclusion liquid chromatography (SE-HPLC) as compared to Glu-D1 x2-y12 allele (%UPP = 54.3%). Genotype was the main determinant of gluten protein characteristics regardless of the nitrogen application and the abiotic stress conditions. The results suggest that the relatively mild drought and heat events in Lithuania might not threaten gluten quality in the future; however, breeding efforts should be directed towards improved drought and heat stress resistance to ensure stable wheat productivity in the region

Affordable phenotyping of winter wheat under field and controlled conditions for drought tolerance

Drought stress is one of the key plant stresses reducing grain yield in cereal crops worldwide. Although it is not a breeding target in Northern Europe, the changing climate and the drought of 2018 have increased its significance in the region. A key challenge, therefore, is to identify novel germplasm with higher drought tolerance, a task that will require continuous characterization of a large number of genotypes. The aim of this work was to assess if phenotyping systems with low-cost consumer-grade digital cameras can be used to characterize germplasm for drought tolerance. To achieve this goal, we built a proximal phenotyping cart mounted with digital cameras and evaluated it by characterizing 142 winter wheat genotypes for drought tolerance under field conditions. The same genotypes were additionally characterized for seedling stage traits by imaging under controlled growth conditions. The analysis revealed that under field conditions, plant biomass, relative growth rates, and Normalized Difference Vegetation Index (NDVI) from different growth stages estimated by imaging were significantly correlated to drought tolerance. Under controlled growth conditions, root count at the seedling stage evaluated by imaging was significantly correlated to adult plant drought tolerance observed in the field. Random forest models were trained by integrating measurements from field and controlled conditions and revealed that plant biomass and relative growth rates at key plant growth stages are important predictors of drought tolerance. Thus, based on the results, it can be concluded that the consumer-grade cameras can be key components of affordable automated phenotyping systems to accelerate pre-breeding for drought tolerance

Genome-Wide Association Analysis and Genomic Prediction for Adult-Plant Resistance to Septoria Tritici Blotch and Powdery Mildew in Winter Wheat

Septoria tritici blotch (STB) caused by the fungal pathogen Zymoseptoria tritici and powdery mildew (PM) caused by Blumeria graminis f.sp tritici (Bgt) are among the forefront foliar diseases of wheat that lead to a significant loss of grain yield and quality. Resistance breeding aimed at developing varieties with inherent resistance to STB and PM diseases has been the most sustainable and environment-friendly approach. In this study, 175 winter wheat landraces and historical cultivars originated from the Nordic region were evaluated for adult-plant resistance (APR) to STB and PM in Denmark, Estonia, Lithuania, and Sweden. Genome-wide association study (GWAS) and genomic prediction (GP) were performed based on the adult-plant response to STB and PM in field conditions using 7,401 single-nucleotide polymorphism (SNP) markers generated by 20K SNP chip. Genotype-by-environment interaction was significant for both disease scores. GWAS detected stable and environment-specific quantitative trait locis (QTLs) on chromosomes 1A, 1B, 1D, 2B, 3B, 4A, 5A, 6A, and 6B for STB and 2A, 2D, 3A, 4B, 5A, 6B, 7A, and 7B for PM adult-plant disease resistance. GP accuracy was improved when assisted with QTL from GWAS as a fixed effect. The GWAS-assisted GP accuracy ranged within 0.53-0.75 and 0.36-0.83 for STB and PM, respectively, across the tested environments. This study highlights that landraces and historical cultivars are a valuable source of APR to STB and PM. Such germplasm could be used to identify and introgress novel resistance genes to modern breeding lines

Multilocal resistance assessment against common bunt of wheat (Triticum aestivum)

Bunt is one of the most devastating diseases of wheat, in Europe and Northern America mainly caused by Tilletia caries and T.controversa, in the warmer climates of the Near East by T.foetida. The generally obligate biotrophic pathogen is trans-mitted by contaminated seeds or can ersist in the soil. Infection occurs at the very first moments after germination of the grain. Once penetrated into the plant, the fungus grows endophytically, remaining undetected until early maturity stages when grains are replaced by spores. Besides yield losses, the malodorant spores contaminate the grains impairing their use as seeds or as food, thereby leading to serious economic losses. Usually the disease is controlled by the use of seed dressings and the use of certified seeds. For organic farming, however, re-sistance of wheat varieties to bunt s crucial as seed treatments with chemical pesticides are not allowed and several proposed alternatives, e.g. treatments with bacteria, hot water, vaccum-steam, steam-ultrasound or electrons, are expensive and lack efficiency. Major and some minor genes conferring resistance to Tilletia infections are described, however, the performance and stability and, therefore, usefulness of these resistances are under debate. Common bunt resistance is based on Flors’ gene for gene principle with an effector of the pathogen and a resistance gene in the host plants, able to detect the effector and to unleash the appropriate resistance mechanisms. To officiently use this type of resistance, it is important to characterize the effectors in the pathogen population as well as to monitor the presence and the efficacy of the resistance genes. While many of this information is available at local and regional level, only little is known at an interregional or even continental dimension. In order to obtain a better overview on the efficacy of resistance genes and the presence and distribution of pathogen races, the European Tilletia ringtest (ETR) was established including also the USA and Iraqi Kurdistan. The ringtest consists of a set of 65 wheat accessions including differentials to characterize the pathogen strains and 40 modern varieties and landraces with specific resistance features. The ringtest took place in 2015 and 2016. First results display a wide diversity of pathogen strains, allowing to recommend the deployment of the most appropriate resistance genes in the different cropping areas. Important differences in disease severity were observed among sites. Resistance was not always linked to the postulated resistance genes. Across all test sites no susceptible plant was observed in PI636170, a breeding line selected from a Turkish landrace. Low infection levels (≤25%) were observed in some breeding lines/genetic resources and also in released cultivars, e.g. Stava and SW Magnifik

Lucerne complexive resistance to deseases

The 41 accessions of lucerne (Medicago sativa, M. varia, M. falcata) were investigated in the field experiment at the Institute of Agriculture in 2008-2009. Experiment period was very favourable for disease spread and development. Resistance between downy mildew (DM) and Sclerotinia crown and stem rot (SCSR) correlated weakly (0.344), the medium correlation (r=0.531) was determined between resistance to spring black stem and leaf spots (SBSLS) and DM, the strong correlation (r=0.704) was found between resistance to SBSLS and SCSR. The medium resistance to SBSLS was characteristic for 17 % of accessions. The resistant to DM were 14 %, and medium resistant were 29 % of accessions. About third of accessions were resistant and medium resistant to SCSR.41 liucernų (Medicago sativa, M. varia, M. falcata) pavyzdys tirtas 2008– 2009 m. lauko bandymuose Žemdirbystės institute. Bandymo laikotarpis buvo labai palankus plisti ir vystytis ligoms. Tirtų liucernos pavyzdžių atsparumas netikrajai miltligei ir vėžiui koreliavo silpnai (r=0,344), vidutinis ryšys (r=0,531) buvo nustatytas tarp atsparumo askochitozei ir netikrajai miltligei, o stiprus nustatytas (r=0,704) tarp atsparumo askochitozei ir vėžiui. Vidutiniu atsparumu askochitozei pasižymėjo 17 % pavyzdžių. Atsparių netikrajai miltligei pavyzdžių nustatyta 14 %, o vid. atsparių – 29 %. Pavyzdžių, atsparių ir vid. atsparių vėžiui buvo 39 %

Lucerne resistance to Sclerotinia crown and stem rot

Lietuvos žemdirbystės institute 2008–2010 m. lauko ir laboratoriniais metodais tirtas 31 liucernos (Medicago spp.) veislės atsparumas vėžiui. Rezultatai, gauti laboratoriniais tyrimo metodais, tarpusavyje labai koreliavo. Buvo palygintas sėklų daigumas, naudojant oksalo rūgšties vandeninį tirpalą (koncentracija 30 mM) ir daiginant jas ant Sclerotinia trifoliorum grybienos, ir nustatyta stipri koreliacija (r = 0,774*, P < 0,01). Lyginant laboratorinius atsparumo nustatymo metodus su lauko tyrimu, taip pat gautos stiprios koreliacijos. Tarp sėklų dygimo ant S. trifoliorum grybienos ir liucernų atsparumo lauke nustatyta r = 0,842*, o tarp sėklų dygimo naudojant 30 mM koncentracijos oksalo rūgštį ir liucernos atsparumo lauke – r = 0,906*. Patvirtinta galimybė atrinkti atsparią liucernos medžiagą per trumpą laiką, naudojant itin paprastas priemones, kurios pagreitina liucernų atsparumo selekciją.The Sclerotinia crown and stem rot resistance of 31 cultivars of lucerne (Medicago spp.) were investigated in the field and laboratory experiments at the Institute of Agriculture in 2008-2010. Results obtained by laboratory methods strongly correlated. The strong correlation (r = 0.774*, P < 0.01) was calculated between seed germination test with water solution of oxalic acid (concentration 30 mM) and seed germination on the mycelium of Sclerotinia trifoliorum. Strong correlations also were calculated between results of laboratory tests and field experiment. Correlation coefficient r = 0.906* was calculated between seed germination test with water solution of oxalic acid and lucerne resistance in the field. Correlation coefficient r = 0,842* was calculated between seed germination on mycelium of S. trifoliorum and lucerne resistance in the field. Confirmed possibility to select resistant lucerne material during short time with small inputs should promote lucerne Sclerotinia crown and stem rot resistance breeding

Naujausios žieminių kviečių veislės – genetinis šaltinis atsparumo ligoms selekcijai

ur experimental evidence suggests that of all the winter wheat cultivars tested only 6.3% possessed complex resistance to powdery mildew (PM) and tan spot (DTR). The cultivars susceptible to both diseases accounted for 50%. The genotypes with only PM resistance were more numerous (29.2%) than those with only DTR resistance (12.5%). Maximal severity of DTR was scored 9, while that of PM - 7 (using a 1-9 scale). The mean of area under disease progress curve (AUDPC) for all cultivars was 188 for PM and 516 for DTR. The cultivars ‘Aperitif ’, ‘Torild’, ‘Striker’, ‘Tulsa’, ‘Director’, ‘Dromos’, ‘Symbol’, ‘Tuareg’ and ‘Brilliant’ possessed the highest complex resistance to both diseases. Maximal severity of PM for these cultivars was scored 4, DTR - 5. The maximal AUDPC for PM was 69 and for DTR 342