Relationship between cold resistance,heading traits and ear primordia development of wheat cultivars

Summary For breeding early heading wheat cultivars with resistance to frost damage which are well adapted to dry areas of West Asia and North Africa, the relationships between winter hardiness, ear primordia development and heading traits, i.e. veernalization requirement, photoperiodic response and narrow-sense earliness, were assessed using a total of 30 genotypes of wheat (Triticum aestivum L.) grown in an experiment in Syria. The results of artificial freezing tests indicated that cultivars with good winter hardiness were to be found only in the winter wheat cultivars which required 50 or more days of vernalization treatment. These winter wheat cultivars did not initiate internode elongation without vernalization even at 95 days after planting. Thus their ear primordia were still underground and were protected from frost injury at this stage. Photoperiodic response and narrow-sense earliness were not associated with winter hardiness and earliness of internode elongation, but were related to the number of days to heading after planting. This indicated the possibility for breeding early heading cultivars with winter hardiness and tiller frost avoidance by combining high vernalization requirement, short narrow-sense earliness and neutral response to photoperiod.     

Relationship between vernalization requirement and winter hardiness in doubled haploids of barley

Summary Progeny lines of chromosome-doubled haploids from crosses between one winter and four spring barley varieties were analysed for winter hardiness and vernalization requirement in the field. About one quarter or less of the offspring lines required vernalization under field conditions showing that winter versus spring habit of growth is controlled by at least two pairs of genes. The vernalization requirement could be measured quantitatively by testing a few plants in a greenhouse after artificial cold treatment during germination. The individual winter lines tested required from two to seven weeks of vernalization in order to flower as early as possible. The cold treatment had no effect on the time of flowering in the spring lines.Winter hardiness varied from zero to 100% plant survival in the field. The majority of the lines requiring vernalization survived better than 90% and the survival of the rest was at least 60%. The winter survival of the spring lines varied from zero per cent (about one third of the lines) to 100%. Hence, it is possible to obtain lines of good winter hardiness without requirements for cold treatment. Conversely, a selection for vernalization requirement has a positive effect on winter hardiness.     

Heterotic patterns in rapeseed (Brassica napus L.): II. Crosses between European winter and Chinese semi-winter lines

Chinese semi-winter rapeseed is genetically diverse from European winter rapeseed. Our objectives were (1) to evaluate the potential of semi-winter rapeseed for winter rapeseed hybrid breeding, (2) to assess the relative importance of general combining ability (GCA) vs. specific combining ability (SCA) among combinations between Chinese semi-winter and European winter rapeseed, and (3) to compare the strategies to predict heterosis based on parental genetic distance (GD) estimated from AFLP marker data and GCA for hybrid performance. Four winter male sterile lines from Germany as testers were crossed with 14 Chinese semi-winter rapeseed lines to develop 56 hybrids, which were evaluated together with their parents and commercial hybrids for seed yield, oil content and protein content under three environments in Germany. The Chinese parental lines were not adapted to local environmental conditions as demonstrated by lacking winter hardiness and poor seed yields per se . However, the hybrids between the Chinese parents and the adapted winter rapeseed lines exhibited high heterosis for seed yield. About 20% of the hybrids were significantly superior to the respective hybrid control under three environments. Additive gene effects mainly contributed to hybrid performance since the variance components of GCA were higher as compared with SCA. The correlation between parental GD and hybrid performance was found to be low whereas the correlation between GCA and hybrid performance was high and significant, with correlation coefficients of 0.95 for seed yield, 0.87 for oil content, and 0.91 for protein content, indicating that GCA can predict hybrid performance. These results demonstrate that Chinese semi-winter rapeseed germplasm has a great potential to increase seed yield in winter rapeseed hybrid breeding programmes in Europe.     

Winter hardiness in Turkish populations of cocksfoot,Dactylis glomerata L.

Summary Over a six-year period, Turkish populations of cocksfoot were investigated in the field at Sapporo, Japan, as to winter hardiness. After the first winter, only populations from the mild Marmara, Aegean and Mediterranean regions were badly damaged. As the differential plant survival among geographical groups widened with the elapsing of years, we were able to rank the groups in descending order of relative hardiness from Eastern Anatolia, through the Black Sea, Central Plateau, Marmara and Aegean regions, to the Mediterranean region. This order was maintained throughout the experimental period.Winter temperatures prevailing in the locality of origin was the most important determinant of winter survival of the populations. The growth pattern in autumn and whether plants continued to grow through the winter or were enforced to winter dormancy, were related to differential survival between maritime and mountainous populations. On the other hand, this simple relationship is complicated by introgression. The subspecies distribution in the coastal region is related to a higher level of survival in the populations from the Black Sea region, where the continental type of cocksfoot occurs, than in the populations from the other maritime regions, where introgression has occurred from Daetylis glomerata subsp. hispanica with poor winter hardiness.Present address: Tropical Agriculture Research Center, Okinawa Branch, Ishigaki 907-01, Japan.     

Ecotypic variation of water-soluble carbohydrate concentration and winter hardiness in cocksfoot (Dactylis glomerata L.)

The variation of the water-soluble carbohydrate (WSC) concentration in foliage and stubble and winter hardiness among cocksfoot (Dactylis glomerata L.) ecotypes originated from diverse countries were studied in the field in order to find a breeding material for the improvement of WSC. The total WSC concentration of foliage was found to be highest in Japanese cultivars and lowest in ecotypes from northern Europe in summer and autumn. The variation of fructan concentration in stubble among ecotypes was larger than the variation of mono and disaccharide concentrations in stubble and that of total WSC concentration in foliage in both winters over which this study was conducted. The total WSC and fructan concentrations in the stubble of ecotypes from Spain and southern Europe, derived from the Mediterranean region, were highest in summer. Ecotypes from Japan showed the highest concentration of total WSC in stubble, and were especially high in fructan concentration in autumn. Ecotypes from France, central Europe and central Asia, like Japanese cultivars, also showed a high fructan concentration. The latitude of origin was negatively correlated with WSC concentration and plant vigor in autumn. The altitude of origin was negatively correlated with plant vigor in autumn and positively correlated with fructan concentration in stubble, winter hardiness and snow endurance. Typhula snow blight resistance was related with the amount of the increase in fructan in the plants and with their growth habits in autumn. The fructan concentration of foliage and stubble in autumn was found to be closely related with winter hardiness in cocksfoot ecotypes. A breeding material which has a high WSC concentration in the foliage could not be found among the ecotypes in this study. However, some ecotypes that showed disease resistance, good winter hardiness and plant vigor would be useful as breeding materials for Hokkaido.     

Relevance of Osmotic and Frost Protecting Compounds for the Winter Hardiness of Autumn Sown Sugar Beet

The cultivation of autumn sown sugar beet (winter beet) is supposed to result in a marked yield increase compared with spring sown sugar beet. Although the importance of the growth stage reached before winter for the survival of autumn sown sugar beet has already been shown, it is not clear to which extent osmotic and potentially frost protecting compounds may contribute to winter hardiness. The study thus aimed to analyse the acclimatization process of sugar beet to low temperatures and to identify compounds which are important for survival of frost. Field trials with autumn sown sugar beet were conducted at eleven environments in Germany from 2009/10 to 2012/13, which were accompanied by greenhouse experiments with controlled temperature regimes. In the field trials, the survival rates after winter varied from 0 % to 99 %, but only in four environments differences between the five genotypes occurred. During acclimatization, betaine, glutamine, proline and raffinose were markedly accumulated and osmolality was enhanced. In particular betaine, amino acids and osmolality showed a positive correlation to the survival rate and were thus identified as potentially frost protecting substances for sugar beet. In contrast, raffinose and proline seem to act rather as stress indicators as they were negatively related to survival. Possible frost protecting substances were identified which can be used in breeding to improve the winter hardiness of sugar beet.     

Variation in Illinois bundleflower (Desmanthus illinoensis (Michaux) MacMillan): A potential perennial grain legume

Illinois bundleflower, Desmanthus illinoensis (Michaux) MacMillan, is an herbaceous perennial legume native to the central and southeastern USA. It has been identified as a potential perennial grain legume. To describe variation among natural populations for agriculturally desirable characteristics, 141 accessions of D. illinoensis and one of D. leptolobus were evaluated in common garden plantings established in 1988 and 1990. Characteristics showing diversity among populations included seed yield, plant height, growth habit, days to maturity, 100 seed weight, and shatter resistance. Eight characteristics were analyzed by principal components and cluster analysis. The resulting four clusters accounted for 56% of the variation among accessions. One cluster was distinctive in having plants with vigorous, prostrate first year growth, poor winter hardiness, and large seed. Three accessions also had indehiscent legumes useful for breeding shatter resistance. There appears to be sufficient variation to support genetic improvement of agricultural characteristics of Illinois bundleflower. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic variation of a safflower germplasm collection grown as a winter crop in southern Spain

Summary A germplasm collection containing 23 accessions of safflower (Carthamus tinctorius L.) was sown in 1993/94 as a winter crop in southern Spain to perform a comparative evaluation. Morphological, physiological and chemical characters were evaluated. Considerable diversity was found in the group. Only one Mexican accession was dwarf (40 cm tall). Most accessions were spiny but there were two spineless Iranian accessions and others with few spines. Variations were also evident for head and seed size. Seed yield per plant varied from 2.5 to 103.5 g and it was correlated with the number of heads, number of branches and plant height. Cultivars with oil content over 35% were identified. Most accessions were of the high linoleic type but there were two with high or intermediate levels of oleic acid, corresponding to the cultivars Ole and Oleic leed. Sowing in November in southern Spain has produced a long growing period (180–240 days) but earliness is common in Indian accessions. A Chinese phenotype with a prolonged rosette stage could be better adapted for cold tolerance. Red flowered spineless cultivars were present in the collection and will be preferred for ornamental or dye purposes.     

Winter Hardiness, Frost Resistance and Vernalization Requirement of European Winter Oilseed Rape (Brassica napus var. oleifera) Cultivars within the Last 20 Years

Cultivars of European winter oilseed rape cultivated in the second half of the 1970s and in the mid-1990s were screened for their winter hardiness, frost resistance and vernalization requirement. A strong correlation between winter hardiness and frost resistance in both groups of rape has been noticed. Among oilseed rapes cultivated in the late 1970s, low erucic acid and particularly double zero cultivars were less winter hard than high erucic acid cultivars. Double zero cultivars were characterized by lower frost resistance and lower vernalization requirement. A significant correlation between vernalization requirement and both frost resistance and field survival has also been shown. Frost resistance of the 1990s (double zero) cultivars was higher than that of double low cultivars from the late 1970s. Their vernalization requirement was still small and did not correlate with either frost resistance or winter hardiness. It was concluded that reduction in the content of glucosinolates in the 1970s involved decrease in winter hardiness and vernalization requirement of cultivars. During the following 20 years winter hardiness of double low cultivars has been improved, but vernalization requirements have not changed. As a result no correlation between winter hardiness and vernalization requirement in contemporary canola cultivars has been observed.     

Extent, variation and breeding impact of natural cross-fertilization in German winter faba beans using hilum colour as marker

Faba bean is a partially allogamous grain legume, mostly sown as spring crop in Central Europe, and in few mild coastal areas of UK and France as a winter crop. A population with a genetically wide base, conceived and selected for superior winter hardiness showing promise as winter crop in Germany was evaluated. The reproductive behaviour of this population was evaluated for its degree of cross-fertilization at five German environments (1999–2001), and inbred lines bred from it, plus one F1 bulk and further checks, were assessed for variation in cross-fertilization at three German environments (2001). Seed hilum colour, a dominant-recessive, biallelic locus, was used as a morphological marker. Cross-fertilization (population mean value of 60%) was shown to be higher than in spring faba beans and was environmentally influenced. Genetic variation was demonstrated, heritability was high (h²= 0.75), and heterosis was negative. Inbred lines with a cross-fertilization of 70% can be easily bred. Breeding synthetic cultivars is recommended, their optimum number of components is expected to be higher than the optimum recommended for spring faba beans. This revised version was published online in July 2006 with corrections to the Cover Date.     

大叶女贞抗寒性及冬季叶片丙二醛和可溶性糖含量的变化

为了探索冬季大叶女贞叶片丙二醛、可溶性糖含量的变化规律及其与植株抗寒性的关系,以不同树龄、不同抗寒性植株叶片为材料,于2011年11月上旬-2012年3月中旬的每1个节气内分别采样,测定叶片丙二醛及可溶性糖的含量,并在2012年4月初对每个采样树冬季受冻情况进行调查。结果表明：不同树龄及不同抗寒性的植株冬季叶片丙二醛及可溶性糖具有不同的变化曲线,低温胁迫下叶片丙二醛及可溶性糖含量出现上升趋势越早、上升幅度越大的植株,其抗寒性越差。丙二醛、可溶性糖反映出的抗寒性与植株实际的受冻情况基本一致,两者可作为植物抗寒性测定的生理指标。优树的抗寒性与普通树或受冻树的差异,是由于其在低温胁迫下的生理调节能力不同所致,这种生理调节能力和植株的遗传性有关,且随着树龄的增加有增强的趋势。     

Comparison of molecular markers and coefficients of parentage for the analysis of genetic diversity among spring bread wheat accessions

The comparison of different methods of estimating genetic diversity could define their usefulness in plant breeding and genetic improvement programs. This study evaluates and compares the genetic diversity of 70 spring wheat accessions representing a broad genetic pool based on molecular markers and parentage relationships. The sample was composed of 32 accessions from the International Maize and Wheat Improvement Center (CIMMYT) and 38 from other breeding programs worldwide. Eight AFLP-primer combinations and 37 pairs of SSR primers were used to characterize the accessions and the Coefficients of Parentage (COP) were calculated from registered pedigrees. The average genealogical (COP) similarity (0.09 with a range of 0.0–1.0) was low in comparison to similarity calculated using SSR markers (0.41 with a range of 0.15–0.88) and AFLP markers (0.70 with a range of 0.33–0.98). Correlation between the genealogical similarity matrix (excluding accessions with COPs = 0) and the matrices of genetic similarity based on molecular markers was 0.34≤r≤0.46 (p <0.05). It is concluded that AFLP and SSR markers are generally in agreement with estimates of diversity measured using COPs, especially when complete pedigree data are available. However, markers may provide a more correct estimate due to some unrealistic assumptions made when calculating COPs, such as absence of selection. Furthermore, both COP and marker distances indicate that CIMMYT accessions are different from the worldwide group of accessions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Winter hardiness in trench celery

A total of 51 red and white commercial varieties of trench celery were grown and examined for winter hardiness at the National Vegetable Research Station. Although some plants of most varieties survived the winter, none showed a commercially useful degree of winter hardiness, in that none were marketable after moderate frost. The red varieties had a significantly better survival than the white varieties. In the first season, single plant selections were made from the varieties having both the highest percentage of winter survival and the best agronomic characters. Although some of the progenies derived from these selected plants by self-pollination showed a small increase in winter survival as compared with their parent varieties when both were grown in the second season, no plants of these progenies were sufficiently hardy to remain marketable after moderate frost. It was concluded that none of the varieties tested showed any promise as a source of winter hardiness to be used in a breeding programme, and that selection for one generation from within these varieties did not improve winter hardiness to a useful extent.     

Patterns of RFLP-based genetic diversity in germplasm pools of common wheat with different geographical or breeding program origins

A set of 292 accessions of common wheat (Triticum aestivum L.) representing 21 germplasm pools based on geographical or breeding program origins was assayed for RFLP diversity. Thirty cDNA and genomic DNA probes and the HindIII restriction enzyme were employed for RFLP analysis. About 61% of all 233 scored bands were present in 75% or more of the accessions. All but one of the 30 probes revealed polymorphism, and the average number of distinct patterns per probe over all accessions was 9.5.Polymorphic Information Content (PIC) values within a pool varied from 0 to 0.9 and depended on the identities of both the germplasm pool and the probe. Rare banding patterns with a relative frequency of ≤0.2 within a pool were detected. These rare patterns were more likely to occur in pools exhibiting high levels of heterogeneity. The highest level of polymorphism was observed in the Turkish landraces from Southwest Asia. The Eastern U.S. soft red winter wheat germplasm pool was more genetically diverse than the other advanced germplasm pools, and nearly as diverse as the Turkish landrace pool. RFLP-based genetic relationships between germplasm pools generally tracked expectations based on common geographical origin, breeding history and/or shared parentages. The Chinese wheat landraces from Sichuan, Tibet, and Yunnan provinces were distinct from other pools. Similarity matrices for among-pool genetic distance estimates based on either band frequencies or banding pattern frequencies showed good correlation with matrices derived from Nei and Li's mean genetic similarity estimates (r=−0.82^** and r=−0.73^**, respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pod volume and pod-filling percentage as additional traits for the characterization of chickpea (Cicer arietinum L.)

Thirty short- to medium-duration chickpea germplasm accessions from diverse geographic origins and with a wide range of physiological and morphological traits were grown in three environments at ICRISAT Asia Center, Patancheru, during 1992/93. Data were recorded on time to flowering, leaf area, 100-seed mass, pod volume, and pod-filling percentage. Quantitative data on the last two traits were recorded for the first time to examine their relevance to the characterization of germplasm accessions and their use as selection criteria in breeding. The accessions exhibited considerable variation for the traits. The broad-sense heritabilities were 0.98 for pod volume and 0.85 for pod-filling percentage. The two traits showed consistent relationships with other morphological characters indicating that the pod volume and pod-filling percentage traits can be utilized in genotype characterization of chickpea.     

Variation in developmental patterns of wild barley (Hordeum spontaneum L.) and cultivated barley (H. vulgare L.)

Summary Six wild barley (Hordeum spontaneum) accessions, from a diverse range of habitats, and two spring-cultivated barleys, were examined for variation in durations of development phases. The durations of the leaf initiation and spikelet initiation phases were longer and spikelet growth phases shorter, in wild than in cultivated barley. Across all wild and cultivated barleys the rate and duration of spikelet initiation were negatively correlated, but neither was related to the number of spikelets per spike. The number of spikelets was positively correlated with the number of leaves and the ratio of the number of spikelets to the number of leaves declined with increasing time to anthesis, indicating that each successive leaf was associated with a diminishing increase in the number of spikelets. The duration of culm elongation and final culm length were shorter in accessions of cultivated barley compared with wild barley. This paper also discusses the feasibility for increasing the number of spikelets per spike through breeding for genetic changes in lengths of pre-anthesis phases of development.Abbreviations ANOVA Analysis of variance - HV Hordeum vulgare - CE Culm elongation - DR Double ridge - HS Hordeum spontaneu - ° Cd Degree days     

Genetic diversity of Brassica napus L. Germplasm from China and Europe assessed by some agronomically important characters

Summary The genetic diversity and relationships among 63 rapeseed accessions, including 34 Chinese, 22 Czech, 2 Swedish, 2 German, one French and 2 Canadian accessions, were evaluated by nine agronomically important characters in the field at Yangling, Shaanxi, China. Significant differences between Chinese and European group in plant height, setting position of the first primary branch, number of siliques of the terminal raceme, thousand seed weight and seed yield per plant were detected. There were significant variations in nine agronomic characters among the tested rapeseed accessions. Ward’s minimum variance cluster analysis based on Mahalanobis distances on the raw data of nine agronomic characters clearly separated the European accessions from the Chinese ones. However, the Chinese accessions with erucic acid free and/or low glucosinolates could not be separated from those Chinese accessions with both high erucic acid and glucosinolates. In general, cluster analysis of the 63 accessions based on the selected agronomic characters was consistent with known pedigree information and geographic origin, as well as the previous RAPD results of these accessions. The European rapeseed could be important germplasm resources for enriching the genetic background of Chinese rapeseed, and vice versa.     

Phenotypic diversity in cold-tolerant peanut (<Emphasis Type="Italic">Arachis hypogaea</Emphasis> L.) germplasm

Tolerance to low temperature is an important prerequisite for optimal performance of peanut (Arachis hypogaea L.) in a number of temperate peanut-growing environments. One hundred fifty-eight peanut accessions belonging to five botanical types, known to be tolerant to low temperature (12°C) at germination, were evaluated for phenotypic diversity for 15 morphological traits in the 2001 rainy season and for 15 agronomic and two seed quality traits in the 2001 rainy and 2001/2002 post-rainy seasons. Analysis of data, using the residual maximum-likelihood approach indicated that variance components due to genotypes were significant for all traits in the rainy and for all but two traits in the post-rainy season. Clustering based on scores of nine principle components delineated four clusters. The cold-tolerant genotypes and the standard control cultivars in the four clusters differed in mean, variance, and range both during rainy and post-rainy seasons for a range of agronomic traits, indicating the diversity among the clusters. The cold-tolerant accessions were superior to control cultivars for several agronomic traits compared with their respective controls in both the rainy and post-rainy seasons, so their use in breeding should result in genetically diverse cold-tolerant high-yielding peanut cultivars.     

Genetic diversity in red clover (Trifolium pratense L.) revealed by morphological and microsatellite (SSR) markers

The NPGS-USDA core collection with 85 accessions of red clover, an important forage species, is little described. The goal of the present study was to evaluate the diversity of a set of accessions from the core collection at the morphological and molecular level in order to extract some valuable accessions for Brazilian red clover breeding programs. Twenty-one morphological traits, collected in field and greenhouse in South Brazil, and seven SSR markers were used to describe 57 accessions from the U.S. core collection and one population cultivated in Southern Brazil. Variation between accessions was large for most of the 21 morphological traits. A cluster analysis based on the morphological traits revealed five distinct clusters that separated the populations according to flowering earliness, as already described, but also according to persistency, growth habit and dry matter productivity. Over seven SSR loci, the number of alleles averaged 11.1 alleles per locus. Genetic diversity measured with SSR markers was high, with a mean expected heterozygosity of 0.86. An analysis of molecular variance revealed that the largest proportion of variation (83.6%) resided at the within population level. Although the molecular markers also separated accessions into five clusters, there was no coincidence between the composition of groups found with morphological and molecular data. Use of genetic diversity in breeding programs requires to use the most promising populations, to combine positive traits such as persistency and forage yield, and probably to use within population variation to detect valuable genotypes that could be used as parents of synthetic varieties.     

Uncover the salt tolerance potential of accessions based on photosynthetic attributes and interaction plot in tomato (Solanum lycopersicum)

Soil salinity, being world's gravest and increasing environmental threat, limits the growth and development in nearly all crop plants. The experiment was laid out to investigate the tomato local and exotic germplasm for morpho‐physiological and photosynthetic attributes under salinity stress (0 (control), 8 and 12 dS m^?1). The phenotype data for morpho‐physiological traits were collected; meanwhile, photosynthetic pigments were analysed also at seedling stage. Analysis of variance, interaction plot, PCV and GCV revealed significantly greater diversity among all accessions for subjecting attributes. Strikingly, principle component analysis (PCA) biplot and cluster heatmap exposed potentially salt tolerant accessions (NAQEEB, BL1076, PBLA1401, 017859, TINY TIM, BL1174, BL1078, PBLA1932, TOMMY TOE, PAKIT and CLN2413) under the highest level of salinity for β‐carotene, lycopene contents, chlorophyll b, carotenoids, pheophytin (b) and total pheophytin. The overall performance of the above‐mentioned accessions was found significant and exhibits tolerant attitude under high salt levels. We suggest that these tolerant accessions might facilitate as a potential source for further breeding programme to improve the agronomically important traits by exploiting both conventional as well as molecular breeding efforts.