Genetic erosion of Ethiopian tetraploid wheat landraces in Eastern Shewa,Central Ethiopia

Ethiopia is a centre of diversity and hosts rich genetic resources of tetraploid wheats. Through time, the wheat materials were subject to genetic erosion. Closer investigation was made to assess the status of loss, and identify the possible causes by studying two districts from East Shewa. Information from primary and secondary sources was reviewed and analysed. Farmers identified 26 tetraploid wheat landraces (21 from Akaki and 17 from Ejere), which were once widely grown in the area. Of these, only six were currently available. Compared to the formerly available number of landraces, the loss of diversity in the study area was estimated to be 77%. In the Ejere locality, the loss was 100% before the launching of the on farm landrace conservation programme, and for Akaki it was 95%. Major factors that contributed to the loss include: (1) introduction and expansion of bread wheat varieties; (2) expansion of tef; (3) lack of a mechanism to re-supply seeds of tetraploid wheat landraces; (4) decline in size of landholdings; (5) changes in land use and cropping patterns; (6) lack of policy support; and (7) expansion of improved tetraploid wheat varieties. The lessons from this study underscore the importance of strengthening the local seed supply system as a prerequisite for sustaining on farm conservation of landraces. Moreover, it is necessary to initiate diversity studies focusing on the distribution and status of tetraploid wheat landraces across the country. Complementing these by molecular analyses is essential in order to assess the genetic distinctness of the landraces.     

Reduced Gelatinization,Hydrolysis, and Digestibility in Whole Wheat Bread in Comparison to White Bread

Wheat, an important crop in North Dakota and the United States, is often used for bread. Health concerns related to chronic diseases have caused a shift toward consumption of whole wheat bread. There has been some indication that the rate and amount of starch digestibility of whole wheat breads may be lower than for their refined flour counterparts. This research investigated the components of whole wheat bread that may reduce starch digestibility and impact nutritional quality. Six formulations of flour were used, which included two refined flours, two whole wheat flours, and two whole wheat flours with added starch. The starch was added to whole wheat flours to increase the starch level to that of the refined flour so that we can determine whether or not the dilution of the starch in whole wheat bread was a factor in lowering the estimated glycemic index (eGI) of whole wheat bread. White and whole wheat flours and breads were evaluated for chemical composition, baking quality by 1 , and eGI by the Englyst assay. Whole wheat breads had significantly (P < 0.05) higher mineral, protein, arabinoxylan, and phenolic acid contents, as well as significantly (P < 0.05) lower eGI. The starch molecular weight was also significantly (P < 0.05) higher for whole wheat and whole wheat + starch breads compared with white breads. The eGIs of refined flour breads were 93.1 and 92.7, whereas the eGIs of whole wheat and whole wheat + starch breads ranged from 83.5 to 85.1. Overall, several factors in the whole wheat bread composition can be found to affect the quality and starch hydrolysis.     

Haplotype analysis of molecular markers linked to stem rust resistance genes in Ethiopian improved durum wheat varieties and tetraploid wheat landraces

The recent emergence of wheat stem rust race Ug99 (TTKSK) and related strains threaten Ethiopian as well as world wheat production because they overcome widely used resistance genes that had been effective for many years. The major cause which aggravates the ineffectiveness of Ethiopian wheat varieties against stem rust is the narrow genetic base on which the breeding for resistance has been founded, however, little is known about the resistance genotypes of Ethiopian durum wheat varieties and tetraploid wheat landraces. The objective of the study was to identify stem rust resistance genes that are present in the Ethiopian tetraploid wheat landraces and improved durum wheat varieties using molecular markers and assess which genes are effective for current Ethiopian stem rust races of Puccinia graminis f. sp. tritici including Ug99. The investigated 58 tetraploid wheat accessions consisted of 32 (Triticum durum s.l. incl. Triticum aethiopicum Jakubz., Triticum polonicum) landraces and 22 registered T. durum varieties released in Ethiopia between 1966 and 2009 and four T. durum varieties from ICARDA. A total of 17 molecular markers (SSR, EST and InDel) linked or diagnostic for stem rust resistance genes Sr2, Sr13, Sr22 and Sr35 were used for genotyping. Haplotype analysis indicated that only few of the Ethiopian durum wheat varieties carried Sr13. The resistant variety ‘Sebatel’ showed a haplotype for Sr2 and Sr22 and variety ‘Boohai’ for Sr22, however further evaluation is needed for the diagnostic value of these haplotypes. This study is the first report on the presence of stem rust resistance (Sr) genes in Ethiopian durum wheat varieties and tetraploid wheat landraces based on linked or associated molecular markers. Thus it might help in the identification of varieties carrying resistant alleles that provide valuable genetic material for the development of new improved varieties in further breeding programmes.     

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.     

Genetic Diversity and Relationships of Wheat Landraces from Oman Investigated with SSR Markers

Little is known about genetic diversity and geographic origin of wheat landraces from Oman, an ancient area of wheat cultivation. The objectives of this study were to investigate the genetic relationships and levels of diversity of six wheat landraces collected in Oman with a set of 30 evenly distributed SSR markers. The total gene diversity, (H_T), conserved in the three durum wheat (Triticum durum desf.) landraces (H_T = 0.46) was higher than in the three bread wheat (Triticum aestivum L.) landraces (H_T = 0.37), which were similar to Turkish and Mexican bread wheat landraces calculated in previous studies. Genetic variation partitioning (G_ST) showed that variation was mainly distributed within rather than among the durum (G_ST = 0.30) and bread wheat (G_ST = 0.19) landraces. Based on modified Rogers’ distance (MRD), the durum and bread wheat landraces were distinct from each other except for a few individuals according to principal coordinate analysis (PCoA). One bread wheat landrace (Greda) was separated into two distinct sub-populations. A joint cluster analysis with other landraces of worldwide origin revealed that Omani bread wheat landraces were different from other landraces. However, two landraces from Pakistan were grouped somewhat closer to Omani landraces indicating a possible, previously unknown relationship. Implications of these results for future wheat landrace collection, evaluation and conservation are discussed.     

Changing parameters of Czechoslovak obsolete and modern bread wheat cultivars (Triticum aestivum L.) over 90 years

Differences achieved in 18 selected morphological, phenological and grain parameters attributable to the wheat breeding process were evaluated on the basis of 262 original Czech and Slovak winter bread wheat cultivars (Triticum aestivum L.) developed during 1911–2008 and cultivated in the field and climatic conditions of Crop Research Institute Prague-Ruzyně for 3 years (2010–2012). The wheat breeding process unambiguously has improved grain production parameters, lodging and mildew resistance compared to wheat landraces and obsolete cultivars. Only wheat landrace ‘Visnovska Hustoklasa’ showed a higher resistance to lodging (8 points), no old cultivars registered till 1930 were resistant to mildew. Nevertheless, these economically positive properties of modern wheat cultivars are negatively reflected in lower crude protein content, protein content’s lower stability year to year, and decreased stability of Zeleny sedimentation. The breeding of wheat cultivars during 1961–1990 points to a key period responsible for these parameter changes. At the same time, within this somewhat older wheat group (from 1961–1990), several perspective wheat cultivars with acceptable spike productivity (e.g., ‘Regina’) and high crude protein stability (e.g., ‘Diana II’) were also identified.     

Farmers perception of pesticide use and genetic erosion of landraces of tetraploid wheat (<Emphasis Type="Italic">Triticum</Emphasis> spp.) in Ethiopia

Perception of farmers’ about the use of pesticides and genetic erosion of tetraploid wheat landraces of Ethiopia was assessed through focus group discussions with farmers, on-farm observations, personal interviews with farmers, by using structured questionnaires of temporal and spatial methods. A total of 1496 farmers from seven provinces in the country were interviewed. Farmers’ knowledge about pesticide increases suggests that they are not happy on using chemicals because of their negative impact on farm land. About 75 % of the farmers believe that, although the use of pesticides may increase the production of wheat, it has a negative impact on (human) health and environment. Women showed a higher concern for pesticides’ harmfulness than men. Farmers’ valuation of genetic erosion was estimated as reduced importance of landraces, as shown by a the lower proportion of landraces either grown or sold on the market. The four most important factors cited for loss of landraces were reduction in land area per capita, displacement by released/modern varieties of hexaploid wheat and teff, reduced benefit from landraces, and displacement by other crops and chat. Genetic erosion of 100 % was observed for Triticum dicoccon in the provinces of Gojam and Gonder and for T. polonicum in Tigray and Gojam. Overall, genetic erosion in the country was 32.0, 35.3, 55.9, 84.4 and 84.4 % for T. durum Desf., T. turgidum L., T. aethiopicum Jakubz., T. polonicum L. and T. dicoccon Schrank, respectively.     

Into the vault of the Vavilov wheats: old diversity for new alleles

Intensive selection in wheat (Triticum aestivum L.) breeding programs over the past 100 years has led to a genetic bottleneck in modern bread wheat. Novel allelic variation is needed to break the yield plateau, particularly in the face of climate change and rapidly evolving pests and pathogens. Landraces preserved in seed banks likely harbour valuable sources of untapped genetic diversity because they were cultivated for thousands of years under diverse eco-geographical conditions prior to modern breeding. We performed the first genetic characterisation of bread wheat accessions sourced from the N. I. Vavilov Institute of Plant Genetic Resources (VIR) in St Petersburg, Russia. A panel comprising 295 accessions, including landraces, breeding lines and cultivars was subject to single seed descent (SSD) and genotyped using the genotyping-by-sequencing Diversity Arrays Technology platform (DArT-seq); returning a total of 34,311 polymorphic markers (14,228 mapped and 20,083 unmapped). Cluster analysis identified two distinct groups; one comprising mostly breeding lines and cultivars, and the other comprising landraces. Diversity was benchmarked in comparison to a set of standards, which revealed a high degree of genetic similarity among breeding material from Australia and the International Maize and Wheat Improvement Center (CIMMYT). Further, 11,025 markers (1888 mapped and 9137 unmapped) were polymorphic in the diversity panel only, thus representing allelic diversity potentially not present in Australian or CIMMYT germplasm. Open-access to DArT-seq markers and seed for SSD lines will empower researchers, pre-breeders and breeders to rediscover genetic diversity in the VIR collection and accelerate utilisation of novel alleles to improve wheat.     

Collecting maize (<Emphasis Type="Italic">Zea mays</Emphasis> L. convar. <Emphasis Type="Italic">mays</Emphasis>) with potential technological ability for bread making in Portugal

The Portuguese maize bread (“broa”) manufactured from traditional maize landraces still plays an important economic and social role on Central and Northern rural communities of the country. However the traditional maize landraces agricultural systems are changing. Local maize landraces are in risk of disappearing because of the progressive adoption of hybrid varieties not suitable for bread production. These changes are contributing to a major loss of genetic diversity. An expedition took place in the Central region of Portugal (Beira Interior and Beira Litoral) with the purpose of collecting enduring maize landraces with technological ability for bread production and to access the possibility of establishing a participatory plant breeding and conservation program. A total of 51 different maize landraces and 175 other varieties of associated crops were collected. Maize landraces showed to maintain high diversity and potential for improvement. The production relayed on small farms with polycrop, quality oriented, sustainable systems. A participatory plant breeding and conservation program would be possible on this region with the proviso that local authorities would be involved. This program would allow a higher valuation of these maize populations, contributing to halt the current loss of these unique Portuguese maize landraces.     

山西小麦品种资源醇溶蛋白组成的遗传变异

利用A-PAGE技术,比较分析了近40年来山西小麦育成品种、外引品种与地方品种在醇溶蛋白组成上的差异,从而揭示山西小麦品种醇溶蛋白的遗传变异。结果表明：山西育成品种与外引品种比地方品种醇溶蛋白谱带数目分别增加了2.1和1.5条。在70条迁移率不同的谱带中,26条从地方品种到育成品种出现频率明显增加,23条明显降低,其余的21条变化规律不明显;分区来看,与地方品种比较,育成品种ω区谱带数目及谱带出现频率的增减变化最大,其次是γ区,β和α区变化最小。同时发现16.5和19.1为双联带,12.9、15.7、17.8为三联带,二者都在ω区但总不同时出现。对3种类型品种的遗传差异分析发现,地方品种间的平均遗传距离明显大于其他2类品种;聚类分析也发现,大多数地方品种、山西育成品种或外引品种总是分别聚在同一亚类,表明地方品种与山西育成品种和外引品种之间编码醇溶蛋白的基因位点存在较大差异,同时也说明近40年来山西育成品种之间、外引品种之间醇溶蛋白的遗传变异水平不高。     

Farmers' valuation and conservation of crop genetic resources

This paper focuses on the value of landraces (traditional and local crop varieties) to farmers in centers of agricultural diversity. Additional information on the factors contributing to the private value which farmers assign to landraces may help to identify a strategy for ensuring the conservation of the crop genetic resources (CGRs) which are embodied in landraces while at the same time minimizing the costs. Economic and ethnobotanical approaches for examining the value of landraces complement one another. A formal economic approach establishes a framework for quantitative analysis while ethnobotanical methods provide qualitative data for assessing the likelihood that particular farmers or farm sectors will maintain landraces. Our research synthesizes the two approaches in order to examine farmer selection of local wheat landraces in relation to that of modern varieties in three provinces in western Turkey. Multiple farmer concerns (e.g. yield, risk, quality), environmental heterogeneity, and missing markets contribute to the persistence of landraces. Household characteristics informing variety choice will also affect the household's perceptions of the importance and value of landraces.     

Characteristics of Noodles and Bread Prepared from Double‐Null Partial Waxy Wheat

Double‐null partial waxy wheat (Triticum aestivum L.) flours were used for isolation of starch and preparation of white salted noodles and pan bread. Starch characteristics, textural properties of cooked noodles, and staling properties of bread during storage were determined and compared with those of wheat flours with regular amylose content. Starches isolated from double‐null partial waxy wheat flours contained 15.4–18.9% amylose and exhibited higher peak viscosity than starches of single‐null partial waxy and regular wheat flours, which contained 22.7–25.8% amylose. Despite higher protein content, double‐null partial waxy wheat flours, produced softer, more cohesive and less adhesive noodles than soft white wheat flours. With incorporation of partial waxy prime starches, noodles produced from reconstituted soft white wheat flours became softer, less adhesive, and more cohesive, indicating that partial waxy starches of low amylose content are responsible for the improvement of cooked white salted noodle texture. Partial waxy wheat flours with >15.1% protein produced bread of larger loaf volume and softer bread crumb even after storage than did the hard red spring wheat flour of 15.3% protein. Regardless of whether malt was used, bread baked from double‐null partial waxy wheat flours exhibited a slower firming rate during storage than bread baked from HRS wheat flour.     

Characteristics of French Bread Baked from Wheat Flours of Reduced Starch Amylose Content

Wheat genotypes of wild type, partial waxy, and waxy starch were used to determine the influence of starch amylose content on French bread making quality of wheat flour. Starch amylose content and protein content of flours were 25.0–25.4% and 14.3–16.9% for wild type; 21.2 and 14.9% for single null partial waxy; 15.4–17.1% and 13.2–17.6% for double null partial waxy; and 1.8 and 19.3% for waxy starch, respectively. Wheat flours of double null partial waxy starch produced smaller or comparable loaf volume of bread than wheat flours of wild type and single null partial waxy starch. Waxy wheat flour, despite its high protein content, generally produced smaller volume of bread with highly porous, glutinous, and weak crumb than wheat flours of wild type and partial waxy starch. French bread baked from a flour of double null partial waxy starch using the sponge-and-dough method maintained greater crumb moisture content for 24 hr and softer crumb texture for 48 hr of storage compared with bread baked from a flour of wild type starch. In French bread baked using the straight-dough method, double null partial waxy wheat flours with protein content >14.3% exhibited comparable or greater moisture content of bread crumb during 48 hr of storage than wheat flours of wild type starch. While the crumb firmness of bread stored for 48 hr was >11.4 N in wheat flours of wild type starch, it was <10.6 N in single or double null partial waxy flours. Wheat flours of reduced starch amylose content could be desirable for production of French bread with better retained crumb moisture and softness during storage.     

Phytochemicals and dietary fiber components in rye varieties in the HEALTHGRAIN Diversity Screen

Ten rye varieties grown in one location were analyzed for their contents of dietary fiber (arabinoxylan and beta-glucan) and phytochemicals (folate, tocols, phenolic acids, alkylresorcinols, and sterols). The varieties included old and modern varieties from five European countries. Significant differences were observed in the contents of all phytochemicals in whole grains and in the fiber contents in the flour and bran. The old French varieties Haute Loire and Queyras had high contents of most phytochemicals, whereas the Polish varieties Dankowskie-Zlote and Warko were relatively poor in phytochemicals. The varieties with a high content of folate tended to have low alkylresorcinol contents and vice versa. Furthermore, high contents of arabinoxylans were associated with high contents in tocols and sterols. The 10 selected rye samples comprising old populations and old and modern varieties from different ecological regions of Europe demonstrate high natural variation in their composition and show that landraces and old populations are useful genetic resources for plant breeding. The contents of single phytochemicals can likely be affected by breeding, and they may be adjusted by the right selection of genotype.     

Quality of Flours from Waxy and Nonwaxy Barley for Production of Baked Products

One nonwaxy (covered) and two waxy (hull-less) barleys, whole grain and commercially abraded, were milled to break flour, reduction flour, and the bran fraction with a roller mill under optimized conditions. The flour yield range was 55.3–61.8% in whole grain and increased by 9–11% by abrasion before milling. Break flours contained the highest starch content (≤85.8%) independent of type of barley and abrasion level. Reduction flours contained less starch, but more protein, ash, free lipids, and total β-glucans than break flours. The bran fraction contained the highest content of ash, free lipids, protein, and total β-glucans but the lowest content of starch. Break flours milled from whole grain contained 82–91% particles <106 μm, and reduction flours contained ≈80% particles <106 μm. Abrasion significantly increased the amount of particles <38 μm in break and reduction flours in both types of barley. Viscosity of hot paste prepared with barley flour or bran at 8% concentration was strongly affected by barley type and abrasion level. In cv. Waxbar, the viscosity in bran fractions increased from 428 to 1,770 BU, and in break flours viscosity increased from 408 to 725 BU due to abrasion. Sugar snap cookies made from nonwaxy barley had larger diameter than cookies prepared from waxy barley. Cookies made from break flours were larger than those made from reduction flours, independent of type of barley. Quick bread baked from nonwaxy barley had a loaf volume similar to that of wheat bread, whereas waxy barley bread had a smaller loaf volume. Replacement of 20% of wheat flour by both waxy and nonwaxy barley flour or bran did not significantly affect the loaf volume but did decrease the hardness of quick bread crumb.     

Genetic variability at the Glu-1 loci in old and modern wheats (triticum aestivum L.) cultivated in Slovakia

The high molecular weight glutenin subunits (HMW-GS) composition at the Glu-1 complex loci, in 23 old original wheat genotypes cultivated in Slovakia several decades ago and 32 modern Slovak and Czech wheat cultivars growed in Slovakia at present were studied by SDS-PAGE. Some of the HMW-GS – subunit pairs 3+12, 17+18, and subunit 20, present in old historical wheats were missing in modern cultivars utilized in Slovakia nowadays. There were observed 15 different HMW-GS encoded by 11 alleles or allelic pairs in old genotypes. Lower number of different HMW-GS and competent alleles were observed in a set of modern wheat cultivars – 11 different HMW glutenin subunits encoded by 8 alleles or allelic pairs. The same number of different HMW-GS patterns was revealed in both sets of wheats. From the point of view of genetic variability, it could be concluded that long-term effort of breeders and decreasing of cultivation of landraces and old cultivars are associated with the loss of several HMW-GS alleles and decreasing of genetic variability of wheats. Molecular characterization can reveal broad allelic variability of old wheat genotypes and landraces. Their maintenance in genetic resource collections can prevent losses of these interesting genes.     

Effect of Pea Flours with Different Particle Sizes on Antioxidant Activity in Pan Breads

Pulses are good sources of vitamins and minerals as well as antioxidants. Current literature supports a role for antioxidants in reducing oxidative damage associated with many health disorders, including cardiovascular disease and cancer. The effects of substitution of 10% (w/w) yellow whole or split pea flour (various particle sizes) in white wheat flour (Canadian Wheat Red Spring) on the phenolic and antioxidant activity of the leavened bread were examined. Antioxidant activity was evaluated with four assays, which included 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), metal chelation (MC), and superoxide (SO) radical scavenging assays. The bread samples had reduced DPPH (5–11% scavenging activity) and MC (5–10% scavenging activity) values compared with their respective raw flours. Decreased activity in both the DPPH and MC assays can be attributed to a reduction in the antioxidant capacity in the bread samples owing to dilution with white wheat flour. The MC values for bread samples showed little variability between the yellow whole and split pea flours (8–10% scavenging activity for yellow whole and 9% for split pea flours), which suggests that the antioxidant activity of bread samples is not dramatically affected by the seed coats. Most pea fractions increased the FRAP scavenging activity and decreased the SO scavenging activity values for the bread samples compared with their respective raw flours. We conclude that thermal processing enhanced the antioxidant activity of the bread samples, limiting the dilution effect associated with flour addition during dough make‐up.     

Genetic diversity assessment of Ethiopian tetraploid wheat landraces and improved durum wheat varieties using microsatellites and markers linked with stem rust resistance

A set of 77 markers was used to describe the genetic diversity in a group of 58 tetraploid wheat accessions. Analysis was performed using 31 neutral SSR markers, 31 SSR/STS markers linked with reported major stem rust resistance genes and 15 SSR markers linked with QTL identified for resistance to Ethiopian stem rust races of Puccinia graminis Pers. f. sp. tritici Eriks. et E. Henn. (Pgt),including Ug99. The material consisted of 32 (Triticum durum s.l. incl. T. aethiopicum Jakubz., Triticum turgidum and Triticum polonicum) landraces and 22 registered T. durum varieties from Ethiopia that were released 1966–2009 and four T. durum varieties from ICARDA. A total of 720 alleles were detected. Considering the three marker sets, the mean number of alleles was higher for major stem rust resistance gene linked markers (9.9) followed by neutral SSR markers (9.2) and markers linked with QTL for stem rust resistance (8.5). Dendrograms derived from UPGMA analysis grouped the accessions into two major clusters. The principal component analysis based on the combination of the three marker sets formed three groups. The 1st group was composed of all the improved varieties, whereas the 2nd and the 3rd group contained the landraces. All the landraces that formed the 3rd group were susceptible to Ethiopian stem rust races of Pgt including Ug99. The information on the extent of the genetic diversity of the improved varieties obtained in this investigation will be helpful for developing appropriate breeding strategies to broadening the genetic base of durum wheat varieties in further breeding programmes.     

A glimpse into the past: Strampelli’s bread wheats legacy

More than 100?years ago, before the rediscovery of Mendel’s laws of inheritance, Nazareno Strampelli started a deliberate crossing programme among Italian and foreign bread wheat genotypes that led to the constitution of over 100 varieties and allowed Italy to significantly increase wheat production. Several varieties enjoyed worldwide popularity and were instrumental in the success of many other breeding programmes. To better understand the reasons of these accomplishments, 84 accessions, representing 50 Strampelli varieties, were characterized for glutenin storage proteins and AFLP patterns, in order to confirm their identification and to assess their genetic diversity. The molecular markers analysis confirmed the correct attribution of most accessions and highlighted the broad genetic variation existing among Stampelli’s varieties. Some genotypes, deemed incompatible with the available pedigree data, were removed from the final analysis. A limited within-variety diversity among genotypes was probably due to incomplete homogeneity and stability of Strampelli materials, but also to the use of heterogeneous local populations as parents.