Variation for resistance to Puccinia hordei in Ethiopian barley landraces

Summary Up to 100 single plant derived lines of 18 Ethiopian barley landraces were evaluated for infection type in the seedling and adult plant stage, and for latent period in the adult plant stage only. A low infection type indicates the presence of race-specific resistance genes of the hypersensitive type, while the latent period is the major component of the polygenic, partial resistance.In the seedling stage 1721 of these single plant derived landrace lines were assessed for infection type against two barley leaf rust races. In the adult plant stage 1227 from these 1721 lines were evaluated for infection type against one race. In the seedling stage 2 (against race 1-2-1) and 29 against race A) out of the 1721 lines showed an infection type lower than 6–7 on the 0 to 9 scale. In the adult plant stage none of the 1227 lines had an infection type lower than 6–7 against race 1-2-1.The variation between and within the landraces for latent period in the adult plant stage was large. Some landraces such as landrace 212845 showed a highly significant and longer mean latent period than most other landraces. Virtually all plants in all landraces carry at least some partial resistance.The near-absence of race-specific, major, resistance genes and the high frequency of moderate levels of partial resistance indicates that the durability of leaf rust resistance in Ethiopian barley landraces is due to the latter type of resistance, and that the multiline principle does not operate.     

Variation in partial resistance to barley leaf rust (Puccinia hordei) and agronomic characters of Ethiopian landrace lines

An inventory of 481 lines derived from 12 Ethiopian barley (Hordeum vulgare L.) landraces and the checks was made for partial resistance to Puccinia hordei under greenhouse and field conditions at Adet, Ambo and Sinana Agricultural Research Centers in 2003 and 2004 cropping seasons in Ethiopia. The experiments were laid out in a triple lattice design. Each plot consisted of two rows of 1–m long with spacing of 0.20 m between rows. The overall mean leaf rust epidemics varied from area under disease progress curve (AUDPC) of 86 to 1,835. The disease was as high as AUDPC 1,378 on the susceptible check L94. Highly significant variations were recorded between and within the landraces/lines in leaf rust incidence, severity, days to heading, plant height, thousand seed weight and yield. Similarly, the variations between and within barley groups from three altitude areas and three ear-types were significant. Landraces 1686, 3255, 3262 and 3783 had the least and landraces 219900, 3975 and 3980 had the highest leaf rust severity. Of the 481 lines tested, 413 (86%) had significantly lower disease than the susceptible check, but not than the partial resistant check Vada. In contrast, the yields were more for lines with less disease than for those with high. The frequency of resistant landraces/lines was more in altitude 2,301–2,500 m, and irregular and two rows ear-types than in lower altitude areas and six rows ear-type. Nevertheless, the correlation and regression analysis revealed the adverse effect of the disease in the yields of barley. The 413 lines with high infection types at seedling stage and lower AUDPC under field conditions possess partial resistance to leaf rust.     

Spanish barley landraces outperform modern cultivars at low‐productivity sites

Barley landraces from the western Mediterranean area have not been thoroughly exploited by modern breeding. This study aims at assessing the agronomic value of a core collection of lines derived from landraces of Spanish origin and to compare them with sets of successful old and modern cultivars. The agronomic performance of a set of 175 barley genotypes, comprising 159 landrace‐derived lines and 26 cultivars, was evaluated in a series of 10 field trials, carried out over 3 years and several locations. The most relevant trait of the landraces was higher grain yield at low production sites than cultivars, which may be related with better ability to fill the grain under stressful conditions. On the other hand, lateness, excessive plant height and lodging were negative traits frequently found in the landraces. Large genotype‐by‐environment interaction (GEI) for grain yield was detected, related partly with differences between germplasm groups, probably indicating local adaptation. GEI was also associated with the interaction of heading time and powdery mildew resistance with temperature.     

Genetic diversity in barley landraces from Syria and Jordan

Summary Single-head progenies derived from barley landraces collected along the Fertile Crescent in Syria and Jordan were evaluated for agronomic, morphological, and quality traits in a typical barley growing area in Northern Syria. A large diversity was observed both between and within collection sites, and in most cases the variation was useful for breeding purposes. Single plant progenies were identified with larger yields and more desirable expressions of agronomic characters than the original landraces. The utilization of this material in a breeding program for dry areas is discussed.     

Variation in Ethiopian barley landrace populations for resistance to barley leaf scald and netblotch

One-hundred and eighty landrace populations and six-hundred single-head plants selected from 60 promising populations were evaluated for resistance to scald and netblotch at three locations in Ethiopia. Each accession was tested with and without the application of 50% of the recommended rate of fertilizer at planting. Plants were rated for disease attack two to four times during the season. Both diseases were enhanced by the application of fertilizer and were more severe at the testing sites of Holetta and Bekoji than at Sheno. The difference in disease resistance among and within populations was considerable. Moreover, populations from Arsi and Bale tend to be more susceptible to scald but more resistant to netblotch than populations from other regions. Populations collected from higher altitudes were more resistant to scald, but susceptible to netblotch, than were populations from lower altitudes. The paper illustrates approaches to the identification of valuable genotypes from landrace populations that can be incorporated into a breeding programme for the development of improved varieties with resistance to the principal diseases of barley in Ethiopia.     

Agronomic diversity of naked barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.): a potential resource for breeding new food barley for Europe

Naked (hulless) barley was neglected by plant breeders in Europe during the period of intensive crop improvement in the 20th Century, but it is now receiving renewed interest due to the potential health benefits it can convey. Very few naked barley cultivars have been developed for modern UK or European agricultural systems, in contrast to the wide diversity of naked barley in Asia. Prior to initiating any breeding programme, phenotyping in UK field conditions is needed to assess the value of existing exotic landraces. This article reports such a programme where naked barley landrace lines were grown alongside modern cultivars and unimproved UK hulled landrace lines over 4 years at a research station in North Wales and assessed for yield and agronomic traits. Multivariate analysis of the traits suggested that accessions clustered by region of origin. Himalayan landrace lines formed Eastern and Western clusters while Japanese and Korean landrace lines were distinct from these. European naked barleys were found to be closest to European hulled barleys, suggesting that the distinctiveness of the Asian naked barley landrace lines was due to origin rather than the naked grain trait per se. The only agronomic trait that could be attributed to naked grain was poorer crop establishment, but some Himalayan landrace lines showed vigorous seedling growth. Modern lines of naked barley from Syria gave superior yields to old UK hulled barleys, indicating that there is potential for breeding modern UK cultivars of naked barley.     

Farmers' seed management practices open up new base populations for pearl millet breeding in a semi-arid zone of India

Farmers in western Rajasthan (north‐west India) produce and maintain their landrace populations of pearl millet through their own distinct seed management practices. The objective of this study was to characterize morphological and agronomic variability of different traits between and within three farmers' populations using quantitative‐genetic parameters. Populations examined were a typical landrace and two modified landraces, which were generated through farmer introgression of modern varieties with different levels of subsequent selection. From these three populations, 100 random full‐sib progenies were evaluated in field trials at two locations in western Rajasthan over two years. Significant genetic variation existed within the three populations. Estimates of heritability were moderate to high for all observed traits. Predicted selection response for grain yield across environments was 1.6% for the typical landrace and 2.2% for both the modified landraces. Results suggest that the introgression of modern varieties into landraces had increased the genetic diversity. Therefore, farmers' current breeding activities could open up new resources for plant breeding programmes aiming at plant improvement for the semiarid zones of India.     

Differentiation among barley landrace populations from the Near East

Summary The structure of variation in 67 barley landraces from Syria and Jordan was investigated by using various morphological and developmental traits measured on spike progenies from the landraces grown in a favorable environment in Syria. Factor analysis was used to identify trait complexes that accounted for major proportions of the total variation among landrace populations.Subsequently, the landraces were clustered into nine distinct groups based on their similarity for all traits. Each group showed a close association to specific geographic or environmental factors, indicating that adaptive processes also are operating in current agricultural systems. These results show the usefulness of thoroughly describing the locations where germplasm accessions originate.Finally, I investigated what proportion of the quantitative variation among landraces was due to differences in plant type. Populations were grouped according to their similarity for qualitatively inherited morphological traits. Subsequent analyses of variance on quantitatively inherited traits showed that this type of classification was as effective as geographic grouping in distributing the variance among and within groups. This result suggests that germplasm collections can be arranged according to either geographic information or morphologic similarity. Practical implications for agronomic evaluation and utilization of germplasm collections are discussed.Journal Paper No. J-12830 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, USA; Project No. 2447.     

Exotic barley germplasm: variation and effects on agronomic traits in complex crosses

Summary Utilization of exotic germplasm offers an approach to broaden genetic variability in breeding populations. This study was conducted in order to 1) compare germplasm of exotic origin with adapted Swedish barleys with respect to genetic differences and 2) to evaluate how exotic material affected agronomic performance in complex crosses. Allozyme studies showed the following Nei's gene diversities among parents: 0.13 (adapted parents), 0.16 (landraces) and 0.25 (H. spontaneum). Cluster analysis indicated that parental groups were genetically divergent. Earliness, straw length, number of ears per plant and thousand kernel weight (TKW) were studied. Variation in agronomic traits showed the following pattern: landraces > H. spontaneum > adapted lines. The best sources for earliness were adapted parents and landraces. Mean straw length was greatest in H. spontaneum lines. Number of ears per plant was quite similar in all groups. The highest TKW was among landraces and adapted parents. Hybrids from the complex crossing programme exceeded parents in earliness and TKW. An index composed from the four traits showed the most favorable frequency distributions for adapted parents and hybrids. Both genetic and agronomic studies indicate that new valuable variation from exotic germplasm may be introduced into barley breeding material.     

Variation within improved cultivars and landraces of lucerne in Central Italy

Summary A variety must be distinguishable, uniform, stable and of sufficient productivity to be officially registered. In Italy landraces of lucerne are still widely used because they are characterized by a good persistence and productivity in their area of origin and adaptation.The landrace from Casalina (20 km south of Perugia, Central Italy) has higher dry matter production than many other commercial cultivars. The objective of this paper was to measure the variation of the landrace Casalina and compare it with that of the commonest cultivars available on the market and with some lines selected from the landrace Casalina.The experiment consisted of 11 entries: Casalina, two selections from Casalina (one for high seed yield and one for frequent cuttings), the registered landrace Italia Centrale and 7 registered cultivars. Each entry was represented by 80 genotypes transplanted in the field 60×40 cm apart in a randomized block design with 4 replications. In 1991 the following characters were recorded on a single plant basis: time of first flowering, height, number of shoots and dry matter yield at the first harvest, time of second flowering, leafiness, height, number of shoots and dry matter yield at the second harvest, height, number of shoots and dry matter yield at the third and fourth harvest. Height, number of shoots and dry matter yield at the first harvest, dry matter at the second and third harvest were recorded during the 1992 season.Casalina was as variable as the other entries in 77% of the comparisons; it was more variable in 8% of the comparisons and less variable in 15% of the comparisons. In conclusion, the variation of landrace Casalina is equal to or less than that of registered varieties so that it could be directly registered at the National Registry of Varieties.     

Performance and Variability of Local Barley Landraces in Near-Eastern Environments

Homozygous lines from six Syrian and two Jordanian landrace populations were tested under highly productive growing conditions in Tel Hadia (1982/83), under drought stress in Breda (1983/84), and under dryland salinity stress in Hegla (1982/83/84) in Syria. Mean grain yield levels ranged between 260 kg/ha and 4850 kg/ha. Under drought and salinity stress, the majority of the landrace lines out-yielded the best cheeks significantly. In Tel Hadia the check cultivars mostly outyielded the landrace lines, but not always significantly. In all environments the harvest index of the landrace lines was near the optimum for barley. They expressed intermediate plant height and time to flowering, high lodging susceptibility under favorable growing conditions, high protein content, and a wide range of yield component combinations. In the stress environments highly significant genetic variation among the landrace lines was found. The heritabilities for gram yield were high in these trials. The correlations between performance under stress and under favorable growing conditions were poor. Therefore, the largest gains for variety improvement for the Syrian steppe area are expected from direct selection under stress conditions. Unique responses in proline accumulation and germination patterns in saline solution indicated specific adaptation in this material. These landraces, thus, are a useful source of breeding material, which also widens the genetic base of the present breeding program.     

Genetic variation and interrelationships of agronomic characters in landraces of bread wheat from southeastern Iran

There is renewed interest in wheat landraces as important sources of genetic variation for agronomic characters. Fifty-three pure lines of bread wheat (Triticum aestivum L.) derived from seven landraces collected from southeastern Iran were used to estimate genetic variation and heritability for 13 developmental and quantitative characters. Path-analysis was used to partition the genetic correlations between grain yield and six grain yield-related traits. Mean values of landraces were also compared with three improved cultivars from California and Iran. Genotypic differences among the landraces and among the pure lines collected from the landraces were highly significant for all characters considered. Compared with the modern cultivars, the landrace genotypes were, on average, later in days to heading and taller than the cultivars but had lower values for number of grains per spike, 1000-grain weight, grain yield and harvest index. Some landrace genotypes were similar to the modern cultivars for grain yield. Moderate to high genetic variation was displayed by number of grains per spike, number of spikes per plant, 1000-grain weight, and harvest index. The heritability estimates ranged from 59% for grain yield to 99% for days to anthesis. Expected genetic advance (as % of the mean) was ≈34% for number of spikes per plant, number of grains per spike, and 1000-grain weight. Days to heading and to anthesis correlated positively with number of spikes per plant, shoot biomass, and straw biomass but negatively with number of grains per spike and harvest index. The strong direct effect of number of spikes per plant on grain yield was completely counterbalanced by its indirect negative effects via number of grains per spike and 1000-grain weight. Number of grains per spike and 1000-grain weight were positively correlated with grain yield, and they had large direct effects. These two characters, however, were negatively correlated and exhibited a substantial counterbalance effect via one another and via number of spikes per plant. The landraces could be improved by intercrossing the promising genotypes identified in this study, with simultaneous selection for earliness, fewer number of spikes per plant, greater number of grains per spike and heavier grains. For further improvement, crossing programs between the landraces and introduced germplasm may be necessary. This revised version was published online in July 2006 with corrections to the Cover Date.     

河北水稻地方种质品质多样性分析

为了揭示河北水稻地方种质资源品质性状遗传多样性,采用多样性指数、主成分分析、聚类分析等方法对收集的109份河北水稻地方种质15个品质性状进行了遗传多样性评价。结果表明：河北水稻地方种质存在丰富的遗传多样性。15个品质性状平均变异系数为23.03%,平均多样性指数为1.92。垩白粒率、垩白度、粒长、蛋白质含量、米饭硬度5个性状多样性指数大于2,表明这些河北水稻地方种质在这些性状上遗传变异丰富。根据主成分分析,15个品质性状可归纳成为4个主成分因子,其累积贡献率包含了15个变量83.04％的信息。米饭食味、直链淀粉含量、精米率、垩白度是影响河北水稻地方种质品质的主要因素。采用4个主成分因子欧式距离聚类分析结果表明,在遗传距离D=16.5处,可以将109份地方种质分为4类,但不同来源的河北地方水稻种质交错分布聚类。本研究为河北地方水稻种质的利用提供了科学依据。     

Environmental and Genotypic Effects on Pod Characteristics Related to Common Bean Quality

A collection of 121 common bean (Phaseolus vulgaris L.) landraces from Spain and Portugal (Iberian Peninsula) was evaluated in six environments (three locations and 2 years). Significant differences among landraces were found for period of flowering, pod maturity and pod morphology (weight, length, width/thickness and curvature). Wide variation among landraces was revealed by the range of variation observed. Environmental effects were not significant although year × location and landrace × year × location interactions were significant for all traits studied except for pod curvature. Poor consistent expression across the different environments for most of the traits studied was expressed by the low values of constancy (C) with the exception of width/thickness indicating that pod shape (round or flat) was expressed regularly across different environments. Principal component analysis enhanced differences among environments affecting the performance of the bean landraces evaluated. Analysis by environment showed that 51 landraces were adapted to specific environments and only four of them had broad geographical adaptability with similar performance under different conditions. These results could be a starting point for selection of new inbred lines adapted to distinct environments with potential for the improvement of current snap bean cultivars.     

Variation for resistance to Fusarium head blight in spring barley

Fusarium head blight (FHB) is a fungal disease of barley and other cereals, causing substantial yield and quality losses, mainly due to the contamination of the harvest with mycotoxins. We aimed to evaluate genetic variation for resistance to FHB and its association with other plant characters in diverse barley germplasm in order to identify useful lines for resistance breeding. The 143 barley lines consisted of 88 current European spring barley lines and cultivars, 33 accessions from the genebank at IPK Gatersleben, and 22 lines obtained from North American institutions. We conducted artificially inoculated field experiments with Fusarium graminearum Schwabe during two seasons. FHB severity was evaluated by repeated assessment of visual symptoms. On a set of 49 lines several trichothecene mycotoxins were analyzed. Variation for FHB severity was quantitative. The lines with lowest FHB severity were 'CIho 4196' and 'PI 566203'. Also within the European spring barley collection variation for FHB severity was highly significant. There was a significant negative correlation between plant height and FHB severity (r=– 0.55). FHB severity assessed in the field and the amount of deoxynivalenol in the harvested grains were positively correlated (r= 0.87). Several lines with a useful level of FHB resistance were found or confirmed and are recommended as crossing partners.     

Genes for scald resistance from wild barley (Hordeum vulgare ssp spontaneum) and their linkage to isozyme markers

Summary Accessions of Hordeum vulgare ssp. spontaneum, the wild progenitor of barley, collected in Israel (70), Iran (15) and Turkey (6) were screened for seedling response to four isolates of Rhynchosporium secalis, the pathogen causing leaf scald in barley. Resistance was very common in the collection (77%) particularly among accessions from the more mesic sites (90%). The genetics of this resistance were investigated in fifteen backcross (BC₃) lines that contained an isozyme variant from H.v. ssp. spontaneum in a H.v. ssp. vulgare (cv. Clipper) background and were resistant to scald. Segregation in the BC₃F₂ families conformed with a single dominant resistance gene in 9 of the 15 lines. Scald resistance and the isozyme marker were closely linked in three of the BC₃-lines, loosely linked in four and unlinked in the remaining eight. Scald resistance genes were identified on barley chromosomes 1, 3, 4 and 6. Crosses between several of the scald resistant BC-lines together with the linkage data indicated that at least five genetically independent resistances are available for combining together for deployment in barley. The linkage of scald resistance in several BC₃-lines to the isozyme locus Acp2 is of special interest as this locus is highly polymorphic in wild barley.     

二棱大麦品种（系）的综合评价

为更精准筛选和选育不同用途二棱大麦品种,对38份不同来源及用途的二棱大麦品种（系）的株高、穗长、千粒重、穗粒数、有效穗数、籽粒产量和不孕粒数等主要农艺性状及籽粒蛋白质含量进行综合评价。结果表明,参试二棱大麦品种（系）有效穗数、产量、穗长、不孕粒数及蛋白质含量变异丰富,株高、千粒重及穗粒数变异相对较小,二棱大麦育种的增产效应主要体现在穗长和有效穗数的适度增加。相关性分析表明,二棱大麦各性状间存在复杂的相关性,且多个性状均可影响产量,有效穗数与产量呈极显著正相关。供试二棱大麦品种（系）在遗传距离10水平上可聚为中秆大粒型和矮秆多穗型两类。主成分分析将38份二棱大麦品种（系）的主要农艺性状分为4个主成分,其累计贡献率达85.5807%;以前4个主成分得分值为指标进行主成分二维排序分析,分析38份二棱大麦品种（系）在特定因子性状上的差异,结果为创制优异种质及亲本选择提供依据。     

Performance of durum wheat landraces in a Mediterranean environment (eastern Sicily)

Summary The evaluation aimed at identifying landrace genotypes adapted to the rather unfavourable growing conditions of durum wheat in Sicily, to be used as parental material in a breeding programme. The trial was carried out in three seasons experiencing varying climatic conditions, and included 75 landraces, 25 of which were selected under severe drought in Syria. Wide differences were observed for most traits among genotypes and seasons of evaluation. Yields of the best performing entries identified in each season never significantly differed from that of the best check variety. The top-yielding landraces were consistently better than the remaining entries for the three yield components, viz. number of spikes per plant, number of kernels per spike and mean kernel weight. In the driest season they were also significantly earlier in heading, confirming the importance of earliness under drought. An analytical breeding approach relying on an array of morpho-physiological traits as selection criteria did not seem appropriate for the given environment, as the variable stress level enhanced the importance of specific traits under specific situations. The genotypic response was largely season-specific. Nonetheless, five landraces were in the best group in all seasons. The selection made in Syria also appeared somewhat effective in Sicily, particularly in the less favourable seasons.     

Variation within and among Ladino white clover ecotypes for agronomic traits

Summary One set of 285 genotypes from three landraces and one natural population and a second set of 165 genotypes from two landraces and one natural population were evaluated in separate trials. Variation among populations was mostly accounted for by the difference between landrace and natural population genotype groups, the former showing features related to higher seed yield and short-term aerial dry matter (DM) yield and to lower persistence, cold tolerance and protein content. Compared to variance among ecotypes, that within ecotypes was never lower and it was at least four-fold higher for important traits such as aerial and total (aerial plus stolon) DM yield, stolon density, production of seed heads and cold tolerance. Landraces and natural populations showed similar levels of intra-population variation for all traits except cold tolerance, for which landraces tended to somewhat greater variation. Trait associations were less definite at the genotype level than what previously found in terms of mean values of the ecotypes. This finding and the relatively high broad sense heritability which was observed for all components of DM and seed yield can support the breeding activity on this clover. The level of variation and of heritability found for protein content do not suggest the routine evaluation of this trait in breeding programmes.     

低氮胁迫下三峡库区玉米地方品种的苗期植株形态及生理效应

以10个来自三峡库区的玉米地方品种为材料,通过盆栽实验和设置低氮胁迫处理,研究低氮胁迫下玉米地方品种的苗期植株形态和生理效应.结果表明,低氮胁迫对玉米地方品种幼苗植株形态和生理有不同程度的不利影响,不同玉米地方品种的耐低氮特性存在明显差异.不同地方品种的同一植株性状和同一地方品种的不同植株性状的耐低氮胁迫指数存在差异.侧根数、叶面积、根体积和植株干重可作为玉米地方品种耐低氮种质筛选的形态指标,硝酸还原酶活性和丙二醛含量可作为耐低氮种质筛选的生理指标.此外,三峡库区玉米地方品种中有较丰富的耐低氮种质可供玉米育种利用.