Six-row Barley Cultivars Research Articles

A transcriptional atlas identifies key regulators and networks for the development of spike tissues in barley

Grain number and size determine grain yield in crops and are closely associated with spikelet fertility and grain filling in barley (Hordeum vulgare). Abortion of spikelet primordia within individual barley spikes causes a 30%-50% loss in the potential number of grains during development from the awn primordium stage to the tipping stage, after that grain filling is the primary factor regulating grain size. To identify transcriptional signatures associated with spike development, we use a six-rowed barley cultivar (Morex) to develop a spatiotemporal transcriptome atlas containing 255 samples covering 17 stages and 5 positions along the spike. We identify several fundamental regulatory networks, in addition to key regulators of spike development and morphology. Specifically, we show HvGELP96, encoding a GDSL domain-containing protein, as a regulator of spikelet fertility and grain number. Our transcriptional atlas offers a powerful resource to answer fundamental questions in spikelet development and degeneration in barley.

Bazı arpa genotiplerinin tuzlu koşullarda çimlenme tepkilerinin değerlendirilmesi

Aims: The aim of this research was to determine the responses of some barley genotypes to salinity stress at the germination period. Methods and Results: Barley seeds provided from the Osman Tosun Gene Bank at Ankara University. Eight six-row barley genotypes (33, 64, 159, 184, 200, 202, 220 and 231) and two six-row barley cultivars (cv Avcı-2002 and cv Cetin-2000) were used in this study. Salinity stress was applied to the seeds in four different doses of NaCl (distilled water (0), 75 mM, 150 mM and 225 mM). The experiments were carried out at 25±1°C and dark conditions with triplicate according to completely randomized plot design. In order to determine the salinity tolerance of genotypes in the study; germination speed (%), germination power (%), root length (cm), shoot length (cm), shoot fresh weight (g), shoot dry weight (g), root fresh weight (g) and root dry weight (g) parameters were measured. Conclusions: As results of these measures, all parameters were found to be statistically significant (p≤0.01) except for germination power and shoot dry weight. Genotype × NaCl dose interaction was found significantly different at p≤0.01 level for germination speed and root fresh weight. Significance and Impact of the Study: Genotype 200 and 220 showed better performance under salinity stress than other genotypes. Also, it can be used as a parental genitor in future breeding studies.

Evaluation of sensitive and tolerant cultivars of barley to salt stress using tolerance indices in central regions of Iran

Background and objectives: Undoubtedly, one of the biggest human challenges in the present age is food security, and salinity stress is one of the main obstacles to achieve this goal. In this regard, this experiment was conducted with the aim of selecting tolerance barley cultivar(s) to salinity stress and identifying tolerance mechanisms in new and old barley cultivars. Materials and Methods: This experiment was carried out during the two years of 2016-17 in the Milshbar Ardakan region located in Yazd province. Experimental treatments included 9 six-rowed barley cultivars including Nik, Mehr, Khatam, Reyhan, Goharan, Nosrat, Morocco, Afzal and Fajr 30 cultivars in three levels of irrigation water salinity including 4, 10 and 14 dS/m were evaluated as a split plot experimental design so that water salinity as the main plots and cultivars as a sub-plots were randomly placed. The studied traits included yield and yield components. At the maturity stage, several plants were selected from each experimental plot and sodium and potassium were measured. Results: The results showed that salinity and cultivar treatment had a significant effect on the yield and yield components including number of seeds per spike, number of spikes per square meter and 1000-kernel weight. Salinity stress reduced grain yield components and among the studied cultivars, Nik, Mehr, Khatam and Reyhan cultivars had higher yield and yield components. Among the salinity treatments, the highest grain yield was obtained at 4 dS/m with 5770.64 kg/ha. With increasing salinity to 10 and 14 dS/m, grain yield decreased by 18.04 and 27.55%, respectively, and reached to 4729.29 and 41.8080 kg/ha. Among the studied cultivars, the highest grain yield was obtained in Nik with 5317.7 kg/ha and Mehr, Khatam and Reyhan were not significantly different with this cultivar. In salinity of 10 dS/m, the lowest grain yield variation were obtained in Goharan and Mehr cultivars and in salinity of 14 dS/m it was in Mehr and Afzal cultivars. The highest STI index in salinity of 10 compared to 4 dS/m was calculated in Nik and Mehr cultivars with 0.922 and 0.921, respectively. The highest value of this index in salinity 14 compared to 4 dS/m was also obtained in Nik and Khatam cultivars with 0.882 and 0.858, respectively. Conclusion: Considering the amount of sodium and potassium absorbed by the plant and the K/Na ratio, it seems that tolerant cultivars cope with salinity stress by the mechanism of potassium uptake and excretion of sodium and regulation of cell osmotic potential. In general, among the studied cultivars, Nik, Mehr and Khatam cultivars had higher stress tolerance indices of STI, MP, Tol and these cultivars can be used for cultivation in saline lands of the region as well as for hybridization and breeding programs.

Changes in stay-green and nitrogen use efficiency traits in historical set of winter barley cultivars

The objective of this study was to compare grain yield, nitrogen use efficiency (NUE) and stay-green traits in winter barley under low and high nitrogen (N) fertilization treatments. Field trials were conducted during two growing seasons in a southern Pannonian location (Novi Sad, Serbia) with fifteen six-rowed barley cultivars released between 1972 and 2013. The rate of genetic gain in grain yield was higher under high N level, indicating that modern barley cultivars use the applied N fertilizer more efficiently than older cultivars. The improvement in NUE and N uptake efficiency were positively related with year of cultivar release under both fertilization levels, while association between N utilization efficiency and year of cultivar release was significant at high N fertilization. Modern cultivars had higher normalized difference vegetation index (NDVI) values at the anthesis, start and mid senescence. Moreover, time to mid senescence was prolonged in modern cultivars, indicating slower N remobilization during early grain filling period. Values of NDVI at different senescence stages were more related to N uptake efficiency, while timing of senescence stages were in association with N utilization. Close association between NDVI values at different senescence stages and N uptake indicate that application of NDVI sensors could be used for identification of cultivars with improved N productivity.

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The objective of this study was to compare grain yield, nitrogen use efficiency (NUE) and stay-green traits in winter barley under low and high nitrogen (N) fertilization treatments. Field trials were conducted during two growing seasons in a southern Pannonian location (Novi Sad, Serbia) with fifteen six-rowed barley cultivars released between 1972 and 2013. The rate of genetic gain in grain yield was higher under high N level, indicating that modern barley cultivars use the applied N fertilizer more efficiently than older cultivars. The improvement in NUE and N uptake efficiency were positively related with year of cultivar release under both fertilization levels, while association between N utilization efficiency and year of cultivar release was significant at high N fertilization. Modern cultivars had higher normalized difference vegetation index (NDVI) values at the anthesis, start and mid senescence. Moreover, time to mid senescence was prolonged in modern cultivars, indicating slower N remobilization during early grain filling period. Values of NDVI at different senescence stages were more related to N uptake efficiency, while timing of senescence stages were in association with N utilization. Close association between NDVI values at different senescence stages and N uptake indicate that application of NDVI sensors could be used for identification of cultivars with improved N productivity.

Grain number and grain weight as determinants of triticale, wheat, two-rowed and six-rowed barley yield in the Pannonian environment

Climate significantly affects cropping systems across Europe. Knowledge of the variability in grain number per unit area and grain weight across different growing seasons and its association with grain yield is important for further improving small grain crop production. The main aim of this study was to compare grain yield and its numerical components among triticale, wheat, two-rowed and six-rowed barley cultivars across different growing seasons in a typical Pannonian location (south-eastern part of Central Europe). Trials with twelve winter cereal genotypes (three two-rowed barley, three six-rowed barley, three wheat and three triticale genotypes) were carried out in four successive seasons in Novi Sad, Serbia. Results of this study showed that growing season, species, cultivar, and species × growing season interaction significantly (p<0.01) affected grain yield and its determinants. Generally, triticale had higher average grain yield, while the lowest grain yield was recorded in six-rowed barleys. Grain yield was more associated with the number of grains/m2 than with grain weight. Heading date was recognized as one of the important adaptive traits in crop development and yield determination. Short duration of the pre-anthesis phase in early cultivars and delayed anthesis in late cultivars significantly decreased the number of grains/spike in different species/spike types, reducing the final grain yield. Medium early cultivars had the highest number of grains/spike due to optimal duration of the pre-anthesis period and heading date and are suggested as recommendable for large scale production in the Pannonian environments.

РЕАЛИЗАЦИЯ ИДЕЙ Н.И. ВАВИЛОВА В СЕЛЕКЦИИ ЯЧМЕНЯ В СИБИРИ

In his publications, N. I. Vavilov used to emphasize the need to use local source material in cereal crop breeding, marking out the value of East Siberian varieties with their long evolutionary background in extreme climate environments. This idea of N. I. Vavilov was proven by the development of barley cultivars in Siberia. In the northern subtaiga and taiga regions of Siberia, six-row barley cultivars are preferred. Crosses between the cultivar ‘Chervonets’ and barley varieties developed in North America resulted in releasing 10 cultivars. In the forest-steppe zone, preference is given to two-row barleys. ‘Viner’ and ‘Omsky 13709’ cultivars participated in the development of 21 new barley cultivars. A breeding program has been worked out and launched to release varieties resistant to a complex of extreme environments.

Shotgun proteomics of the barley seed proteome

BackgroundBarley seed proteins are of prime importance to the brewing industry, human and animal nutrition and in plant breeding for cultivar identification. To obtain comprehensive proteomic data from seeds, total protein from a two-rowed (Conrad) and a six-rowed (Lacey) barley cultivar were precipitated in acetone, digested in-solution, and the resulting peptides were analyzed by nano-liquid chromatography coupled with tandem mass spectrometry.ResultsThe raw mass spectra data searched against Uniprot’s Barley database using in-house Mascot search engine identified 1168 unique proteins. Gene Ontology (GO) analysis indicated that the majority of the seed proteins were cytosolic, with catalytic activity and associated with carbohydrate metabolism. Spectral counting analysis showed that there are 20 differentially abundant seed proteins between the two-rowed Conrad and six-rowed Lacey cultivars.ConclusionThis study paves the way for the use of a top-down gel-free proteomics strategy in barley for investigating more complex traits such as malting quality. Differential abundance of hordoindoline proteins impact the seed hardness trait of barley cultivars.

Effects of planting date and earliness on deoxynivalenol contamination in barley under natural epidemic conditions

Choo, T. M., Martin, R. A., Savard, M. E. and Blackwell, B. 2014. Effects of planting date and earliness on deoxynivalenol contamination in barley under natural epidemic conditions. Can. J. Plant Sci. 94: 1363–1371. Fusarium head blight, principally caused by Fusarium graminearum Schwabe, is a destructive disease of barley in many countries and it can result in mycotoxin contamination such as deoxynivalenol (DON) in the grain. An integrated management strategy is needed to mitigate the level of DON contamination in barley. Therefore, a study was initiated to determine if early planting and early-heading cultivars can be used to avoid severe DON contamination under natural epidemic conditions in the Maritimes. Twelve six-row barley cultivars were planted in a split-plot design with two planting dates (early vs. late) as main-plot units and cultivars as sub-plot units at the Harrington Research Farm in Prince Edward Island in 2007, 2008, 2010, 2011, and 2012. Grain samples from all experimental plots were contaminated with DON and one contained as high as 23.1 mg kg−1. Early planting frequently resulted in less DON contamination and higher yield than late planting. Days to heading was positively correlated with DON concentration only at late planting in 2007. The results of this study suggest that six-row barley should be planted early in the Maritimes to avoid a high level of DON contamination and a reduction in grain yield, and that use of early-heading cultivars may not be effective at reducing DON contamination while retaining high yield.

Characterization and mapping of a Prbs gene controlling spike development in Hordeum vulgare L.

The barley mutant, poly-row-and-branched spike (prbs) showed altered inflorescence morphology: complete conversion of the rudimentary lateral spikelets in two-rowed barley into fully developed fertile spikelets similar to the six-rowed phenotype, and additional spikelets in the middle of spike. Moreover, branched spikes emerged in progeny from a cross between the mutant and a six-rowed barley cultivar. Morphological observation of the development of immature spikes of the mutant and descendants with branched spikes showed that the Prbs gene is involved in spikelet development in the triple-mound stage. In mutant prbs, new meristems initiated at the flanks of lateral spikelets and middle spikelet meristems were converted to branch meristems, developing branched spikes. These observations suggested that the Prbs gene plays a crucial role in spikelet initiation and identity maintenance. The Prbs gene may be an important modifier in inflorescence differentiation from a panicle into a spike. The branched spikes emerging in hybrids from a cross between the mutant and six-rowed barley cultivar were not conferred by the gene vrs1 or Int-c, which decide spike morphology in six-rowed barley. These results imply that although six-row genes vrs1 and Int-c and prbs have similar effects on lateral spikelet development, they have different functions in branched spikes. The Prbs gene was mapped to chromosome 3H between SSR marker Bmag0023 and marker Cbic60 at a genetic distance of 3.3 and 5.4 centimorgans (cM), respectively.

オオムギ縞萎縮病抵抗性を有し，稈の折損が発生しにくい麦茶用六条オオムギ新品種「カシマゴール」の育成

オオムギ縞萎縮病抵抗性を有し，稈の折損が発生しにくい麦茶用六条オオムギ新品種「カシマゴール」の育成

Genetic diversity analysis of barley landraces and cultivars in the Shanghai region of China

We analyzed the genetic diversity of 115 barley germplasms, including 112 landraces and three new barley cultivars grown in the Shanghai region, using a set of 11 SSR markers. Sixty-six alleles were observed at the 11 SSR loci, ranged from three to ten, with a mean of six alleles per locus. The polymorphism information content ranged from 0.568 to 0.853, with a mean of 0.732, indicating considerable genetic variation in barley in the Shanghai area. Clustering analysis indicated that these barley accessions could be divided into two categories (A and B). Ninety-seven six-rowed barley cultivars were classified in the A category; sixteen two-rowed and two six-rowed barley cultivars were classified in the B category. This demonstrated genetic differences between two-rowed and six-rowed barley varieties. In addition, we found that the three new barley cultivars are closely related.

Tracking Amylolytic Enzyme Activities during Congress Mashing with North American Barley Cultivars: Comparisons of Patterns of Activity and β-Amylases with Differing Bmy1 Intron III Alleles and Correlations of Amylolytic Enzyme Activities

This study was conducted to test three hypotheses: 1) that α-amylase will have less consistent patterns of activity during mashing than will β-amylase and limit dextrinase; 2) that differing β-amylase 1 intron III alleles (Bmy1.a and Bmy1.b) would not be useful in predicting high or low activities or thermostabilities among cultivars; and 3) that correlations of α-amylase versus β-amylase activities would be more significant than for either amylase versus limit dextrinase during the initial 55 min of mashing, when the bulk of wort sugars are produced. Malts of six two-row and six six-row barley cultivars were mashed, and amylolytic enzymes were assayed at six time points during mashing. α-Amylase activities of four cultivars peaked at 30 min (45°C), six at 55 min (70°C), and two at 75 min (70°C). β-Amylase activities of all cultivars peaked sharply at 30 min (45°C) into mashing and declined precipitously thereafter, rapidly approaching near nil by 75 min. Limit dextrinase activities of 11 of 12 cultivars peaked at 55 min (70°C), and one peaked at 30 min (45°C). These data indicate no uniform pattern for the development of α-amylase activity compared with patterns for β-amylase and limit dextrinase during mashing. Steptoe, a feed barley cultivar, had much lower peak activities for all three amylolytic enzymes than did malting cultivars. The highest β-amylase activities during mashing of cultivars with either the Bmy1.a (Legacy, Lacey, and Morex) or Bmy1.b (Merit and Harrington) intron III alleles were not significantly different as determined by least significant difference (LSD) analysis (P < 0.0001). As temperatures increased from 45 to 70°C (55 min), percentages of the highest β-amylase activities decreased from 11.9% (Rasmusson) to 41.5% (Steptoe). LSD analysis revealed that Steptoe (Bmy1.a allele) had significantly higher β-amylase thermostability than did malting cultivars. The highest malting barley thermostabilities for β-amylases (Lacey [Bmy1.a allele] and Harrington [Bmy1.b allele]) were not significantly different (P < 0.0001). Correlations of α-amylase versus β-amylase activities were positive and significant in seven of nine possible correlations from 5 to 55 min of mashing, whereas α-amylase and β-amylase versus limit dextrinase activity correlations over the same period were significant in two of nine and one of nine correlations, respectively. This study supports all three of the proposed hypotheses.

Tracking the Progress of Congress Mashing with Osmolyte Concentration and Malt Extract Value in North American Barley Cultivars and Relationships between Wort Osmolyte Concentration, Malt Extract Value, and ASBC Measures of Malt Quality

This study was conducted to test three hypotheses: 1) barley malt osmolyte concentration (OC) would increase more rapidly during mashing than malt extract (ME); 2) OC would better discriminate between differing barley malts during mashing than ME; and 3) OC after mashing would better correlate with ASBC measures of malt quality than ME. Malts of six two-row and six six-row barley cultivars were mashed in a micromasher, and aliquots were removed for wort OC and ME measurements at six time points during a 115-min mashing regime. For all cultivars combined, over the first 55 min of mashing wort OC values increased 120% compared with 91% for ME. At the end of the mashing regime (115 min) wort OC values further increased to 132%, whereas wort ME values remained approximately the same (91–92%). This indicates that the mass of material in wort remained approximately the same after 55 min but was further degraded to lower molecular weight compounds, increasing wort molarity and, thus, OC but not ME. Steptoe, a feed barley, was separated to a much greater degree from elite malting cultivars by wort OC than by ME values throughout the mashing regime. Except for very early in mashing (5 min), there was better separation of all cultivars by OC than by ME values throughout mashing, as determined with least significant difference analysis, indicating that OC may be better than ME for judging differences in cultivar malt quality. Linear correlations of time-course mash OC versus ME values were excellent for all cultivars combined (r = 0.977, P < 0.0001) and for two- and six-row cultivars separately. Correlations of the 115-min mashing OC and ME values with ASBC malt quality measurements were considerably better for OC than for ME (e.g., wort protein [r = 0.819, P = 0.001 for OC; r = 0.407, P = 0.189 for ME]; diastatic power [r = 0.765, P = 0.004 for OC; r = 0.287, P = 0.365 for ME]; α-amylase [r = 0.737, P = 0.006 for OC; r = 0.584, P = 0.046 for ME]; and β-glucan [r = −0.0.754, P = 0.005 for OC; r = −0.0.595, P = 0.041 for ME]). This study supports all three hypotheses.

Competitive interactions of fifty barley cultivars with Avena sterilis and Asperugo procumbens

A 2-year study was conducted in northern Greece to assess the ability of 29 six-row and 21 two-row barley ( Hordeum vulgare L.) cultivars to compete with winter wild oat [ Avena sterilis spp. ludoviciana (Durieu) Gill & Magne] and German-madwort ( Asperugo procumbens L.). The fresh weight of both weeds grown in competition with six of the most competitive six-row barley cultivars (Bulk Resist. Desc-Sutter, Lignee 640, Paico's, Mantnan's-EH 165, Pistacho and Malebo) was reduced by 61–75% compared with one of the least competitive six-row cultivars [Gloria's-Copal's (30B-4Y-20M)]. The corresponding fresh weight reduction of both weeds grown in competition with three of the most competitive two-row barley cultivars (Goldmarker, Shanon and Helena) ranged from 59 to 76% compared with one of the least competitive two-row cultivars (Guanajuato). The ability to withstand competition (AWC) from winter wild oat and German-madwort of the six-row and two-row cultivars ranged from 33.7 to 78.3% and 26.7 to 69.2%, respectively. Representative yield losses ranged from 24 to 68% and 30 to 75%, respectively. The corresponding ability to compete (AC) indices ranged from 22.5 to 64.8% and 21.1 to 59.1%. The results of this study indicated that the barley cultivars Ligne 640 and Pistacho (2B-1Y-1B) had high AWC from winter wild oat and German-madwort and provided high grain yield in both weedy and weed-free conditions. Consequently, they could successfully be used in Mediterranean organic (no herbicide use) and conventional agricultural systems with reduced herbicide use. Barley cultivars with high AC and ability to produce high grain yield under weedy conditions [with Bulk Resist. Desc-Sutter, Arupo's and Gloria's-Copal's (30B-4Y-23M) among the most efficient] could also successfully be used in organic fields infected by the two weeds.

A Comparison of Barley Malt Osmolyte Concentrations and Standard Malt Quality Measurements as Indicators of Barley Malt Amylolytic Enzyme Activities

This study was conducted to test the hypothesis that barley malt osmolyte concentration (OC) would correlate better with malt α-amylase, β-amylase, and limit dextrinase activities than do the standard malt quality measurements (malt extract, diastatic power [DP], α-amylase activity as measured by the ASBC method, soluble/total protein [S/T], and β-glucan concentration). Seeds of four two-row and four six-row elite North American barley cultivars were steeped and germinated in a micromalter for 6 days. At intervals of 24 hr throughout germination, green malt was removed, kilned, and assayed for individual amylolytic activities, standard measures of malt quality, and OC. Over all days of germination for all cultivars combined, malt OC correlated well with α-amylase, β-amylase, and limit dextrinase activities (r = 0.891, 0.659, and 0.889, respectively; P < 0.0001). With all cultivars combined, most standard measures of malt quality did not correlate as well with malt amylolytic enzyme activities as did OC (low to high correlations with α-amylase activity [S/T: r = 0.676, P < 0.0001; β-glucan concentration: r = −0.840, P < 0.0001]; β-amylase activity [S/T: r = 0.385, P = 0.0068; β-glucan concentration: r = −0.597, P < 0.0001]; and limit dextrinase activity [S/T: r = 0.636, P < 0.0001; β-glucan concentration: r = −0.847, P < 0.0001]). Two expected exceptions were α-amylase activity as measured by the ASBC method, which correlated better with α-amylase activity as measured by the Megazyme method than did OC, and DP, which correlated better with β-amylase activity than did OC. In general, combined two-row cultivar malt OC and standard malt quality measurements correlated better with individual amylolytic enzyme activities than those measurements of combined six-row cultivars, and in general, OC correlated better with amylolytic enzyme activities than did standard malt quality measurements of combined two- or six-row cultivars. With individual cultivars, no malt quality measurement correlated consistently better with amylolytic enzyme activities, although OC correlated consistently well. Overall, with populations of cultivars malt OC was usually a consistent and better indicator of individual malt amylolytic enzyme activities than were standard measures of malt quality, supporting the tested hypothesis.

PHYTOTOXICITY OF 10 WINTER BARLEY VARIETIES AND THEIR COMPETITIVE ABILITY AGAINST COMMON POPPY AND IVY-LEAVED SPEEDWELL

SUMMARYA field experiment was conducted in 2002/03 (year 1) and repeated in 2003/04 (year 2) to study the competitive ability of 10 winter barley (Hordeum vulgare) cultivars against common poppy (Papaver rhoeas) and ivy-leaved speedwell (Veronica hederifolia). The phytotoxic (or allelopathic) activity of barley extracts was also determined in the laboratory using a perlite-based bioassay with barnyard grass (Echinochloa crus-galli). In the field, biomass of both weeds was reduced more (65–79%) by the competition of Alpha, Esterel, Terova or Lignee 640 barley cultivars, than with Aspen or Tersey. Biomass of ivy-leaved speedwell in competition with each barley cultivar was significantly lower than that of common poppy. In year 1, the six-row barley cultivars caused greater weed biomass reduction than the two-row, but this was not the case in year 2. Grain yield of Tersey, Aspen and Goldmarker cultivars in herbicide treatments was greater by 41, 33 and 17%, respectively, than from the corresponding herbicide untreated plots. However, grain yield of Terova, Alpha, Esterel and Lignee 640 was not significantly affected by the presence of weeds. In the laboratory, barley extracts affected the total fresh weight or root length of barnyard grass more than its germination. The germination, root length or total fresh weight inhibition on barnyard grass caused by the two six-row barley extracts was greater (43, 48 and 56%, respectively) than that caused by the eight two-row extracts (22, 34 and 43%, respectively). The results of this study indicated that barley cultivars with great competitive and/or phytotoxic ability could be used in sustainable cereal production systems in order to minimize herbicide usage.

Effects of foliar application of BAP on source and sink strength in four six-rowed barley (Hordeum vulgare L.) cultivars

Effects of foliar application of BAP on source and sink strength in four six-rowed barley (Hordeum vulgare L.) cultivars

Effects of foliar application of BAP on source and sink strength in four six-rowed barley (Hordeum vulgare L.) cultivars

A field experiment was conducted to investigate the effects of foliar application of a synthetic cytokinin (BAP) on source and sink strength of four different six-rowed barley (Hordeum vulgare L.) cultivars. Different spraying treatments consisting of spraying on whole plant, spraying only on leaves and spraying only on ears started at anthesis and continued for 7 days. One additional spraying was carried out on late period of grain filling. Results showed that spraying only on leaves did not affect ear weight, grain yield and 1,000-grain weight, while the two other treatments increased all above mentioned traits. Neither of treatments affected stem weight, biological yield and contribution of stem reserves in grain filling. Exogenous cytokinin did not increase photosynthetic rate and chlorophyll content in treated leaves until late period of grain filling, although there was no significant increase in final grain weight due to late application of BAP. Our results suggested that effects of foliar application of BAP were mostly due to increased sink size soon after anthesis and increased sink demand probably met by current photosynthesis of organs other than leaves, like ear green tissues.

Analysis of Genetic Diversity in Barley Cultivars Reveals Incongruence Between S-SAP, SNP and Pedigree Data

Accurate assessment of genetic similarity is important for plant breeding, germplasm enhancement and conservation of plant genetic resources. A comparative analysis of genome diversity among a group of six-rowed spring barley (Hordeum vulgare L.) cultivars was carried out using sequence-specific amplified polymorphism (S-SAP) and single nucleotide polymorphism (SNP), with the results compared to the kinship coefficients derived from the pedigree data. Mean pair-wise GS values were estimated to be 0.0957 ± 0.144 (Kinship), 0.491 ± 0.189 (SNPs), and 0.602 ± 0.098 (S-SAPs). S-SAP and SNP-based genetic similarity (GS) values were normally distributed but kinship values had a non-normal and skewed distribution. Pair-wise correlation of GS values were lowest for the S-SAP and the SNP matrices (r =; 0.040, p<0.230) and highest for the SNP and pedigree matrices (r =; 0.240, p < 0.001). Analysis of molecular variance (AMOVA) attributed about 90.4% of observed variation to the cultivars within each of the malting and feed groups. Variance component between malting and feed groups was 6.6% for both SNP and S-SAP data suggesting lack of a significant genetic differentiation along this agronomic division. The remaining 3% of variation was attributed to genetic diversity within cultivars. Although both DNA-based marker systems were able to differentiate all barley cultivars, significant difference were observed in the pattern of genetic relationships obtained by the two marker systems and the pedigree data.