Diversity in cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis> (L.) Walp.) local populations from Greece

Cowpea cultivation in many countries around the Mediterranean Basin depends on a number of locally adapted populations conserved on-farm at a small scale, rather than on the use of modern varieties. Documentation, characterization and exploitation of traditional local populations could contribute to their conservation and utilization as sources of desirable characteristics. Therefore, a study was conducted to (a) characterize, (b) assess diversity and (c) classify 23 on-farm conserved local cowpea populations based on 32 agro-morphological traits. Investigations on diversity of characteristics related to seed yield, mineral and seed crude protein content as well as on correlations among them were carried out. A relatively high phenotypic diversity was observed. In particular, a high level of within population diversity was found (\( \bar{H}s \) = 0.34) exceeding that among populations’ diversity (Gst = 0.27). Principal component analysis classified the majority of local populations into two groups (mainly according to populations’ seed coat color and eye color), further divided into six subgroups regardless of the populations’ geographical origin. Significant differences were also observed among the populations studied for potassium and calcium, as well as for their seed crude protein content which ranged from 22.14 to 28.37 %. The results show appreciable levels of intra- and inter-phenotypic diversity in on-farm conserved cowpea populations, which indicates the existence of a valuable gene pool for future exploitation in breeding programs.     

Genetic diversity,population structure and linkage disequilibrium in Nordic spring barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L. subsp. <Emphasis Type="Italic">vulgare</Emphasis>)

Genetic diversity, population structure and genome-wide linkage disequilibrium (LD) was estimated in Nordic spring barley (Hordeum vulgare L. subsp. vulgare) by genotyping 180 breeding lines with 48 SSR markers and 7842 high-confidence SNPs using the Illumina Infinium 9K assay. In total 6208 SNPs were polymorphic and selected for further statistical analysis. A Mantel test revealed a strong positive correlation with a Pearson’s correlation coefficient (r) of 0.86, between the estimates of genetic distances based on SSR and SNP data. Population structure analysis identified two groups with a clear ancestry and one group with an admixed ancestry. The groups were primarily separated based on row-type and geographical origin. Average LD for the whole population decayed below a critical level of r² = 0.20 within a range of 0–4 cM. To avoid confounding effects of the strong population structure, LD decay for the different groups was analysed separately and ranged from 0 to 12 cM. A slower LD decay was found within the two-rowed lines compared to the six-rowed lines and the two-rowed lines originating from the northern part, which could be the result of strong selection for malting quality and yield in the southern part. No large difference in genetic diversity was observed between population sub-groups, but differences at certain chromosomal regions were evident.     

Traditional seed management and genetic diversity in barley varieties in high-hill agro-ecosystems of Nepal

Chawali and Lekali are two common farmer’s barley varieties or landraces in Jumla, Nepal (2,240–3,000 m) with small to bold grains and wide adaptation from irrigated low lands to high hills. This study was undertaken to test whether features of the traditional seed system can significantly influence the diversity of a crop and its conservation on-farm. In Jumla (high-hill), the barley seed system is completely informal and is mainly from farmer to farmer. In the present study, the seed flows and the pattern of genetic diversity in barley were investigated to detect differences between the two varieties and test the divergence among populations of each variety These data suggested that Chawali, the more common variety, was less subject to homogenising gene flow between farms than was Lekali. A total of 128 farming households were surveyed for seed supply information and 128 populations for each landrace from two villages: Kartikswami and Talium were collected for SSR diversity analysis. Some 92 SSRs were screened in an initial sample of 20 barley populations of both landraces and 2 improved varieties (LG-51 and Soluwa). Of the 81 SSRs that consistently amplified, only 15 SSRs (19%) were polymorphic with gene diversity values ranging from 0.09 to 0.71. A medium to low diversity was detected among the landrace populations of barley varieties. Chawali populations were less polymorphic within ecological groups, and more divergent between than were Lekail populations. This result accords with Chawali having a more conservative local seed system.     

Genetic diversity in farmer grown spring barley material from Kyrgyzstan

Barley (Hordeum vulgare L.) is one of the economically important cereal crops grown in the highlands of the Kyrgyz Republic. In marginal agricultural areas of the country barley is considered as irreplaceable and very suitable fodder crop for livestock. In this study the genetic diversity of currently grown farmers’ spring barley material from Naryn and Issik-Kul provinces is described. In order to capture maximum diversity present in farmer field’s different morphological types were collected. The 22 spring barley accessions collected in 2008 were described morphologically and analysed using fourteen simple sequences repeat (SSR) markers. Most material was two-rowed barley, 78 %, whereas six-rowed barley was only 22 %. The spike colours present were light yellow, dark yellow, brown and violet. The material varied also for such characters as length of spike and number of kernels per spike. For the SSR loci 129 alleles were detected with an average of 9.3 alleles per locus and a genetic diversity with an average of h = 0.721 per locus. Based on analysis of molecular variance the 71.3 % of genetic diversity accounted for within accession variation, whereas 27.4 % for among accession variation. The variation between provinces was not significantly different. A group of two-rowed barley was identified that was more closely related to six-rowed barley than to the rest of the two-rowed barley material. Two-rowed material currently grown in Kyrgyzstan is more diverse than six-rowed barley (h = 0.65, A = 8.8 vs. h = 0.59, A = 3.1). From this study we could conclude that the materials nowadays grown by farmers are mixtures. Since there are no geographic differentiation between these mixtures suggests that materials is frequently inter-exchanged between farmers and are most probably not landrace material. The question concerning the origin of these mixtures remains unsolved and further investigation will be carried out to identify sources of variation in farmers’ field.     

Assessment of genetic diversity in Egyptian barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) genotypes using SSR and SNP markers

A barley core collection can be studied extensively and the derived information can be used to identify loci/genes for the genetic improvement of quantitative and qualitative traits. To assess genetic diversity, allelic variation and population structure of Egyptian barley, 134 barley genotypes collected from a different region along with 19 cultivated genotypes obtained from of the Egyptian Agricultural Research Center. All genotypes were analyzed with 261 polymorphic SSR and SNP alleles. The mean number of alleles per locus was 4 and PIC was 0.49, while the level of genetic diversity was 0.55 ranging from 0.03 to 0.82. The genotypes were assigned to three subpopulations that were consistent with their origins. The genetic variation within population was higher (51%) than among population at the molecular levels (F_ST =?0.491 when P?<?0.10). The level of polymorphic variation was highest in subpopulations-II, due to collected from different regions with different ear-types thus, expected to contain more diversity than local genotypes in subpopulations-I and subpopulations-III. The structured study found that the 153 barley genotypes are in harmony with clustering approaches using the SSR and SNP genotypic data in a neighbor-joining tree and principal components analysis, which identified three subpopulations. These results demonstrated genetic diversity among the Egyptian barley genotypes can be applied to suggest approaches, such as association analysis, classical mapping population development, and parental line selection in breeding programs. Therefore, it is necessary to use the exotic genotypes as the genetic resources for developing new barley cultivars in Egypt.     

Genetic diversity in local cultivars of garden pea (Pisum sativum L.) conserved ‘on farm’ and in historical collections

During a national Swedish collection mission of vegetable varieties conserved ‘on farm’ more than 70 pea accessions were obtained, many of which had been grown locally for more than 100 years. In spite of a likely origin in the multitude of obsolete commercial pea varieties available on the Swedish seed market in the nineteenth century, the rediscovered local cultivars have lost their original names and cultivar identity while being maintained ‘on farm’. To analyze genetic diversity in the repatriated material, 20 accessions were genotyped with twelve SSR markers and compared with 15 obsolete cultivars kept in genebanks and 13 cultivars preserved as non-viable seeds collected in 1877–1918. Most of the local cultivars were genetically distinct from each other, and in only a few cases could a possible origin in a tested obsolete cultivar be suggested. These results reflect the wide diversity of pea cultivars present in Sweden during the nineteenth century. Both between and within accession genetic diversity was larger among the historical samples of obsolete cultivars compared to local cultivars and cultivars preserved in genebanks, indicating genetic erosion over time both in genebanks and during conservation ‘on farm’. The constraints on identifying and verifying historical cultivars using genetic markers are discussed.     

Spatially structured genetic diversity of the Amerindian yam (Dioscorea trifida L.) assessed by SSR and ISSR markers in Southern Brazil

Dioscorea trifida L. (Dioscoreaceae) is among the economically most important cultivated Amerindian yam species, whose origin and domestication are still unresolved issues. In order to estimate the genetic diversity maintained by traditional farmers in Brazil, 53 accessions of D. trifida from 11 municipalities in the states of São Paulo, Santa Catarina, Mato Grosso and Amazonas were characterized on the basis of eight Simple Sequence Repeats (SSR) and 16 Inter Simple Sequence Repeats (ISSR) markers. The level of polymorphism among the accessions was high, 95 % for SSR and 75.8 % for ISSR. The SSR marker showed higher discrimination power among accessions compared to ISSR, with D parameter values of 0.79 and 0.44, respectively. Although SSR and ISSR markers led to dendrograms with different topologies, both separated the accessions into three main groups: I—Ubatuba-SP; II—Iguape-SP and Santa Catarina; and III—Mato Grosso. The accessions from Amazonas State were classified in group II with SSR and in a separate group with ISSR. Bayesian and principal coordinate analyzes conducted with both molecular markers corroborated the classification into three main groups. Higher variation was found within groups in the AMOVA analysis for both markers (66.5 and 60.6 % for ISSR and SSR, respectively), and higher Shannon diversity index was found for group II with SSR. Significant but low correlations were found between genetic and geographic distances (r = 0.08; p = 0.0007 for SSR and r = 0.16; p = 0.0002 for ISSR). Therefore, results from both markers showed a slight spatially structured genetic diversity in D. trifida accessions maintained by small traditional farmers in Brazil.     

Genetic relationships among improved varieties of rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) in Indonesia over the last 60 years as revealed by morphological traits and DNA markers

Morphological traits and two kinds of molecular markers were employed to study the genetic relationships among improved rice (Oryza sativa ) varieties of Indonesia since 1943. Dendrograms based on morphological traits and both molecular markers (simple sequence repeats, SSR and single nucleotide polymorphism, SNP) agreed in separating the varieties into two primary groups. Based on the morphological traits, a larger group (>60 %) contains varieties with smaller sizes compared with those in the smaller group (<40 %). SSR and SNP markers revealed that most of the varieties belonged to indica (88; 89 %) and japonica (9; 8 %) subspecies, and 3 % of varieties were not involved in two subspecies. The molecular markers revealed that the genetic diversity (H) stagnated between stage II (1967–1985) and stage III (1986–2003). However, during stage I (1943–1966), H was higher than in the other stages as revealed by SNP markers, while H in stage I was lower than in the other stages as revealed by SSR markers. In this study, the two molecular data sets were positively correlated and positive correlations between the phenotypic and molecular data depended on the kind of molecular marker: SNP had higher Mantel r values than SSRs. Besides, SSR markers seem to be appropriate for pedigree studies, while SNP markers could be used to reveal genomic relationships. These findings were attributable to the different properties of these two different markers. These results suggested that the diversity and differentiation of both the phenotypic and molecular marker variations were probably resulted from the crossing and selection in rice breeding in Indonesia. We suggest that Indonesia needs another strategy to improve new varieties to avoid a reduction in genetic diversity and similarity.     

Population genetics of traditional landraces of <Emphasis Type="Italic">Cucurbita pepo</Emphasis> L., 1753 in the cloud forest in Baja Verapaz,Guatemala

Little is known regarding the effect of fragmentation and human agricultural management on the genetic variation and gene flow of Cucurbita pepo L., 1753 in moderate fragmented areas in central Guatemala. We hypothesize that the genetic variation of C. pepo is affected by forest fragmentation and by traditional agricultural management. Therefore, we aim to determine: (1) the genetic diversity and genetic structure of C. pepo in the Cloud Forest Corridor (CFC) (2) the extent of genetic admixture between commercial variety (CV) and traditional landraces (TL) of C. pepo, (3) the effect of habitat fragmentation in the population genetics of C. pepo with a landscape approach, and (4) the potential relationship between traditional management practices and genetic diversity of C. pepo in the CFC. We detected the existence of high level of genetic diversity (AR = 3.43; He = 0.50), inbreeding (Fis = 0.25) and moderate population structure of C. pepo in the CFC (Fst = 0.16). No correlation between landscape and genetics was found. Also, we found high genetic admixture between CV and TL. It seems that human practices, mainly related with seed exchange patterns, could affect genetic diversity of C. pepo in the CFC. C. pepo populations in the CFC are structured, with inbreeding, and show admixture with the CV, an aspect that could affect its genetic diversity. The agricultural management influenced the population genetics of C. pepo in the CFC, but the landscape did not. We suggest that special efforts should be made to preserve the diversity of this important indigenous food source for Guatemalan people as well as their management practices.     

The Sierra Norte of Madrid: an agrobiodiversity refuge for common bean landraces

At the mountain area close to the city of Madrid, common beans were one of the main food crops present in everyday diet until 1960. This paper describes the morphological diversity, for forty-six phenological and morphological traits, found in forty-three traditional varieties of common beans collected in this area and seven commercial varieties used as reference. That comparison suggests that common bean breeding programs have led to later varieties with a higher production of straight pods. Quantitative traits showed also similar values when compared to the Iberian common bean collection, except for the phenological and seed size characters. The phenological differences could suggest an ecological adaptation of the studied landraces to the regional environmental conditions. The different seed size averages of both collections might correspond to the scarce presence of smaller seed-type common beans in Madrid collection. All the accessions collected in the Sierra Norte of Madrid belong to any of the groups included in the Spanish core collection. Madrilenian collection is also composed by indeterminate growth habit varieties, while the presence of bush accessions is relatively uncommon. Most of the Madrilenian landraces have a remarkable fitness for green-pod consumption (42 %) and their seeds are mainly white (30 %), ovate-shape (49 %) and medium-large (40 %). The study of seed storage protein allowed to classify the landraces according to their domesticated gene pools. Most of them (72 %), with T and C phaseolin type, seem to belong to Andean germplasm, while the remaining (28 %), with S and B phaseolin type, to Mesoamerican one. The remarkable morphological diversity of common beans found in this small area is a symptom of a broad genetic base despite genetic erosion, what indicates a widespread crop in the past. Therefore, it is advisable to design agro-environmental policies to promote the production and commercialization of common bean landraces in Sierra Norte of Madrid.     

Water yam (Dioscorea alata L.) diversity pattern in Brazil: an analysis with SSR and morphological markers

Substantial progress was made in the last decade in understanding the diversity in Dioscorea species. However, most of the studies so far concentrated in the ‘yam belt in Africa’. We present a genetic diversity and structure analysis among commercial and local varieties of water yam (Dioscorea alata L.) in Brazil using microsatellite and morphological markers. Twelve microsatellite primers were used to generate DNA profiles of 72 local varieties and 17 commercial accessions of water yam collected in four different regions in Brazil. Also, four morphological traits were evaluated on individual plants under field conditions. The morphological characterization showed considerable diversity. High polymorphism was found with 100 % polymorphism observed for 11 primers and a discriminating power value of 0.92, on average. We did not observe a strong population structure among sampling regions, while most of the genetic diversity was concentrated within regions (95.9 %). Analysis of the relationship between accessions did not clearly separate the local and commercial genotypes. However, the molecular analyses of D. alata showed high intraspecific diversity in local accessions from different regions in Brazil, with the highest Shannon index value (H′ = 0.41) for the Southeast region. These results confirmed an admixture of accessions in all sampling regions, consistent with the lack of a significant correlation between geographic and genetic distances, suggesting that farmers exchanged water yam materials extensively. The genetic diversity can be explained by the result of a continuous exchange of accessions by farmers throughout Brazil.     

Genetic diversity and parentage in farmer varieties of cacao (Theobroma cacao L.) from Honduras and Nicaragua as revealed by single nucleotide polymorphism (SNP) markers

Cacao (Theobroma cacao L.) is the main source for chocolate with an annual production of four million tons worldwide. This Neotropical tree crop was domesticated in Mesoamerica as far back as 3,000 years ago. Knowledge of genetic diversity and population structure in farmer varieties of cacao in the center of domestication is essential for sustainable production of fine-flavored cacao beans and contributes to in situ/on-farm conservation of farmer varieties. Based on 70 single nucleotide polymorphism markers, we analyzed 84 fine-flavored farmer varieties collected from traditional cacao farms in Honduras and Nicaragua. The study also included 31 clones from the international cacao collections to serve as references. The SNP based multilocus matching identified six synonymous groups, including 14 Criollo and two Amelonado varieties. A moderately high level of genetic diversity was observed in these farmer varieties, indicating the possibility to further explore intra-population variation and breed for fine-flavored cocoa. Multivariate analysis showed clustering of the 84 farmer accessions in five genetic groups: ancient Criollo, Amelonado, Trinitario (including Nicaragua Trinitario and Honduras Trinitario) and Upper Amazon Forastero (only one accession). The Honduras Trinitario differed from the Nicaragua Trinitario group. The clustering results largely supported the perceived classification of cacao by local farmers and researchers, which was mainly based on morphological traits. However, the well known traditional variety “Indio” in this region was identified as synonymous with Amelonado. Parentage analysis showed that the variety “Indio” (or Amelonado) contributed more to the Trinitario type farmer varieties, whereas ancient Criollo had less influence. The present study demonstrates the efficacy of using a small set of SNP makers for cacao germplasm characterization, and further depicts the diverse origins and parentage in farmer varieties from Mesoamerica. This information thus will be highly useful for conservation and utilization of cacao germplasm from this region.     

Genotypic and phenotypic changes in wild barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> subsp. <Emphasis Type="Italic">spontaneum</Emphasis>) during a period of climate change in Jordan

Climate change and other anthropogenic disturbances can lead to the loss of genetic variation and thereby affect evolutionary potential and survival of plant populations in the wild. We examined these predictions in the primary wild relative of barley, Hordeum vulgare L. subsp. spontaneum (K. Koch) Thell., within its center of diversity, in Jordan. Changes in genotypic and phenotypic diversity were assessed using seed samples collected in 1981 and 2012 from the same 18 sites across Jordan. The overall population structure was conserved, but we observed an increase of within population genetic diversity and a reduction in population differentiation. Phenotypic variation differed among years and sites but the magnitude and direction of change variated among sites. While the sampled region became significantly hotter and drier during this period, simple correlation models did not support association between measures of climate change and the observed genetic and phenotypic changes. Agricultural activities that promote disturbance and demographic fluctuations may affect crop wild relatives that grow in agricultural landscapes, in unexpected ways. The observed increase in genetic diversity within populations might be explained by increased migration or by an advantage of increased genetic variation in the face of variable environmental conditions. This study provides a new perspective on the range of possible responses of crop wild relatives to environmental pressures.     

Genetic diversity analysis of hulless barley from Shangri-la region revealed by SSR and AFLP markers

For adding the hulless barley resources of Shangri-la region to the global barley resource library, a basic work was done by us to assess their genetic diversity of this region. The genetic diversity of 60 hulless barley samples collected from three counties in Shangri-la region of Yunnan Province, were studied using SSR (simple sequence repeats) and AFLP (amplified fragment length polymorphism) markers. A total of 70 alleles were detected for 19 pairs of SSR primers, and 525 band containing 464 polymorphic bands were revealed for 5 pairs of AFLP primers. The value of polymorphism information content (PIC) ranged from 0.03 to 0.86 for SSR primers. The total numbers of alleles were 51, 55, 43 in three populations and the polymorphic bands were 188, 205 and 141. The genetic distances and genetic identity among the three populations showed their close relationship. The gene diversity among populations relative to the total population diversity (Gst) was 0.13 for SSR markers and 0.02 for AFLP markers and indicated that just 13 and 2% variations were among populations, respectively. The UPGMA cluster analysis revealed that all of the samples grouped randomly rather than clustered into distinct groups corresponding to their populations, row types and spring/fall types. We concluded that there was high genetic diversity in the population of Shangri-la region and the formation of diversity was related to complex environment and inhabitants’ traditional practices.     

Genetic diversity and population structure of Chinese Cherry revealed by chloroplast DNA trnQ-rps16 intergenic spacers variation

Chinese Cherry, generally referring to Prunus pseudocerasus Lindl. species, is one of the most economically important domestic fruit tree in China. To effectively preserve and sustainably utilize this species, a study in genetic diversity and population structure was carried out by the sequence variation of chloroplast DNA trnQ-rps16 intergenic spacers. Polymorphism was calculated among the 200 individuals from 7 local and 10 wild populations across its geographical range in China. The results showed that (1) Total genetic variation in species level was poor (h = 0.478, π = 0.0018). But in the wild populations, it was much higher than that in the local populations (h = 0.565, π = 0.0021 vs. h = 0.152, π = 0.0006). (2) Low levels of genetic differentiation (F_SC = 0.19595, P = 0.000), genetic distance (0.00000–0.00297), as well as pairwise Fst value among populations were detected. These results, combined with the insignificant gene genealogy pattern and neutrality tests indicate that Chinese Cherry has relatively low levels of genetic diversity and insignificant population structure. Coancestry might be a combined effect of the reduction in effective population size with the recent demographic bottlenecks and mating systems. The pronounced seed dispersal abilities and relatively high rates of gene exchange are supported by the limited genetic differentiation among populations.     

The domestication and dispersal of the cultivated ramie (Boehmeria nivea (L.) Gaud. in Freyc.) determined by nuclear SSR marker analysis

Ramie (Boehmeria nivea) was domesticated in China. However, the geographic region of domestication is not exactly known. Genetic diversity and population structure of ramie and their wild relatives were assessed using microsatellite markers. The 8 microsatellite primers revealed 96 alleles in 50 ramie populations, with an average of 10.25 alleles per locus. Cultivated ramie gene pool harbors approximately 82.9 % of the SSR diversity presented in wild B. nivea var. nivea. It is suggested that ramie has experienced a relatively moderate domestication bottleneck. The distribution of genetic diversity shows that genetic diversity is relatively high in populations along the Yangtze River compared to the peripheral ones. The scatter plots of principal coordinates analysis indicated that there are three well-supported varieties in B. nivea. The NJ tree and the distribution of genetic diversity showed that ramie has been domesticated in the middle and lower regions of the Yangtze valley, and populations in Sichuan province have been introduced from this region, forming naturalized populations.     

Target region amplification polymorphism (TRAP) for assessing genetic diversity and marker-trait associations in chickpea (Cicer arietinum L.) germplasm

The effective utilization of crop diversity held in genebanks depends on our knowledge of useful traits and available markers associated with the target traits. Target region amplification polymorphism (TRAP) was used to evaluate the genetic diversity and underlying relationships among 263 accessions of chickpea landraces maintained by the USDA-ARS Western Regional Plant Introduction Station in Pullman, WA, USA. Two-hundred sixty-two TRAP markers were amplified by eight primer combinations. Altogether, 110 (42 %) markers were polymorphic, the other 152 (58 %) displayed no variation. These polymorphic markers revealed important differences among the accessions, with an estimated, mean pair-wise genetic distance of 25.82 %, ranging from 2.8 to 50.0 %. Genetic distance analysis divided the accessions into two major groups, with 113 and 150 accessions each, and substantial association between molecular diversity and geographic origin was evident. Bayesian analysis of population structure revealed two groups (K = 2) with evidence for six sub-groups. Additionally, the population structure of a subset of 110 lines was determined (K = 3) for testing marker-trait associations (MTAs). Phenotypic traits included the concentrations of protein and nine mineral elements in the seeds. Two MTAs were significant (p < 0.01) for concentrations of Ca and K, and three MTAs were significant for Cu and Ni concentrations. The results indicate that this population is useful for genome-wide association studies on other economic traits given the level of genetic diversity uncovered and the marker-trait associations in seed minerals discovered.     

RAPD-based assessment of genetic relationships among and within American ginseng (Panax quinquefolius L.) populations and their implications for a future conservation strategy

American ginseng (Panax quinquefolius) is a native North American medicinal plant that is becoming increasingly vulnerable despite government harvest restrictions. To better understand the genetic diversity and gene flow of American ginseng, we studied RAPD variation in cultivated and wild populations. Classical and Bayesian analogues of genetic diversity statistics were estimated in seven wild and two cultivated populations. The wild populations were more highly structured (G _stβ  = 0.41) than the cultivated populations (G _stβ  = 0.24). The genetic diversity within populations ranged from H _eβ  = 0.05 to 0.38. Based on genetic pairwise distances, six of the wild populations clustered with the locally-derived cultivated population, while one wild population was more similar to the non-local cultivated population than the local populations. This wild population was highly diverse (P = 1.0; U = 1.0) suggesting that it was supplemented from exotic seed. A set of eight RAPD markers was identified that differentiated plants of local and non-local origin. As a conservation strategy, we recommend that regional gene banks be established based on molecular and geographic diversity to preserve the locally adapted germplasm. These regional gene banks would serve as a conservation tool and also provide a source of genes for genetic improvement of cultivated ginseng.     

Potassium placement effect on dynamics of barley (Hordeum vulgare L.) nutrition

The effects of local placement of potassium (K) on mineral nutrition dynamics of barley (Hordeum vulgare L.) in fertile Сhernozem were studied. A pot experiment with local K-placement at 4–5 cm soil depth was carried out and the dynamics of nitrogen, phosphorus, potassium (NPK) concentrations in tillers, organs and parts of spring barley was measured. K-placement increased the productivity index from 0.49 to 0.54, despite optimal and slightly varying NPK concentrations during the second half of the vegetation period (60–100 d). This occurs due to partitioning of assimilates, N, K, and especially P in generative organs of primary and secondary tillers forming quality grains. Nutrient concentrations in certain primary tiller parts of a 60-d plant (senescing leaves and the main spike axis) proved to be more sensitive indicators of the K-placement effect than average whole-plant characteristics. While being beneficial, K-placement had little impact on the overall NPK removal in barley, which shows a significant role of factors related to K uptake kinetics. Thus, the chosen parameters in the soil–plant system (the high content of available K in Chernozem, in the second part of the vegetation period) have for the first time allowed the evaluation of the impact of local K-placement on mineral nutrition dynamics in barley.     

Phenotypic diversity and evolution of farmer varieties of bread wheat on organic farms in Europe

The contribution of farmers to the creation and maintenance of genetic diversity is beginning to receive more recognition in developed countries. Although the use of landraces and historic varieties has largely disappeared in countries with industrialized agricultural systems and formal seed markets, certain varieties with particular cultural significance have been continuously cultivated by farmers and other varieties have been preserved ex situ in genebanks. Recently, associations of organic farmers have become involved in the conservation and use of landraces and historic varieties (called farmer varieties in this article) because these varieties possess agronomic and quality traits that they have not found in modern varieties. In this study, eight farmer varieties of bread wheat from Europe selected by participating farmers were evaluated in on-farm trials during 3 years of cultivation. Each variety was grown on each farm, and phenotypic changes in each variety were measured the third year in a replicated split-plot trial on each farm comparing the version of each variety the farmer had multiplied to a sample of each variety from the region of origin. All varieties, including the two modern pureline varieties used as checks, showed statistically significant phenotypic changes over 3 years of multiplication. However, the magnitude of these changes was moderate and did not call into question varietal identity or distinctness. In addition, some traits of putative agronomic and adaptive importance, such as grain weight per spike and thousand kernel weight, did not respond positively to natural selection (environmental conditions and management practices) which suggests the necessity of farmer selection to maintain and improve varietal performance.