Associations among productivity,production response,and stability indexes in oat varieties

Summary We tested three sets of oat varieties for grain yield in a series of environments and observed that generally more than 80% of the yield variation for individual varieties was due to linear regression response. Mean yields for varieties were significantly variable in all three sets, and regression response indexes were significantly variable in two of them.Mean yields over the three sets were correlated with regression response indexes with r=0.61. Associations of mean yield with the three stability parameters (i.e., coefficient of determination, mean square for deviations from regression, and ecovalence) were low and usually not significant. The correlation of regression response indexes with coefficients of determination was 0.42, but neither of the other stability parameters was associated with the response indexes. The three stability parameters were closely correlated with one another.Our materials were selected varieties, so evidently our results suggest what can be accomplished in breeding for combinations of mean production, production response, and productiom stability.Journal Paper No.J-9092 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, USA 50011. Project 1752. This work was supported in part by the International Atomic Energy Agency, vienna, Austria, in the form of a fellowship for the senior author.     

Genetic variation among European maize inbreds for resistance to the European corn borer and relation to agronomic traits

The univoltine European corn borer (ECB) has become a major limiting factor for maize (Zea mays L.) production in central Europe. The objective of this study was to survey the genetic variation for ECB resistance in European elite maize germplasm. Eighteen flint and 23 dent inbreds were screened under artificial ECB infestation at two locations in 1993 and 1994. Resistance was assessed by damage rating of broken plants, measurement of tunnel length in dissected stalks, and yield reduction in infested plots relative to insecticide-protected control plots. Flint lines showed significantly greater means for damage rating than dent lines with grain yield reduction of 35% and 24%, respectively. Significant genotypic variances among lines and high heritabilities were found for agronomic traits and damage rating. Heritabilities were intermediate for tunnel length and relative grain yield. Significant associations of days to silking, ear dry matter content, and dry matter yield of the whole plant with damage rating and tunnel length suggested a better resistance in late-maturing, high-yielding inbreds. Genotypic correlations of relative grain yield with tunnel length and damage rating ranged between ?0.46 and ?0.72. Partial correlations, eliminating the effect of flowering time, confirmed these associations. Damage rating of stalks is the most suitable trait for evaluation of ECB damage owing to its high heritability and easy recording. Tunnel length below the primary ear is a useful trait for assessing antibiosis because it is not correlated with days to silking. Inbreds with extreme resistance and susceptibility were identified which can be used as parents for establishing breeding and QTL mapping populations.     

The physiology of variation in the time of ear emergence among wheat varieties from different regions of the world

Summary Differences in response to photoperiod and vernalization and genetic variation independent of photoperiod and vernalization (earliness per se), affecting time of ear emergence of wheat, were identified in controlled environment experiments with 33 varieties of diverse geographical origin. The results were compared with an analysis of time of ear emergence of 10409 T. aestivum accessions from the USDA Small Grain Collection grown from autumn sowings in Pendleton, Oregon, and spring sowings in Fargo, North Dakota. The effect of differences in photoperiod and vernalization sensitivity on time of ear emergence was similar to the effect of earliness per se, both under controlled environment conditions and in the field. Most of the accessions from low latitude regions reached ear emergence rapidly owing to their insensitivity to photoperiod and vernalization and earliness per se factors accelerating ear emergence. Lateness was common among accessions from Northern Europe, Afghanistan and Turkey, which was due to sensitivity to photoperiod and vernalization, and to earliness per se factors delaying ear emergence. The physiological basis of earliness per se is discussed.     

Genetic relationships among grapevine varieties grown in different French and Spanish regions based on RAPD markers

The genetic relationships among 32 white grapevine varieties (Vitis vinifera L.) grown in different French and Spanish regions were surveyed by using RAPD markers. Two hundred and eight clear and unambiguous RAPD markers were amplified by using 33 primers previously selected. Genetic relationships were established by UPGMA cluster analysis and also by studying RAPD low frequency bands. Three groups of varieties were clearly defined. The stability of the genetic structuration was surveyed by Student t-test and the confidence for certain nodes of the dendrogram was confirmed by bootstrap method. Varieties were separated in clear geographical groups with Atlantic or Mediterranean influence. Some of them were classified according to a common cultivation area and ampelographic characters, suggesting a common origin. In addition, ‘Albariño’, ‘Caíño Blanco’ and ‘Loureiro Blanco’ from Galicia (Spain) and ‘Melon’, ‘Chardonnay’ and ‘Aligoté’ from Burgundy (France) were closely related varieties. Two new closely related couples were defined as ‘Godello’ and ‘Verdejo’, and ‘Malvar’ and ‘Malvasía’.     

Molecular genetic diversity within and among German ecotypes in comparison to European perennial ryegrass cultivars

Perennial ryegrass (Lolium perenne L.) is the most important grass species for temperate grassland agriculture. The level and distribution of genetic variation in gene bank ecotype collections is still largely unknown but of great interest for the planning of breeding programmes. The objectives of this study were to (i) assess the molecular variance and population structure of German ecotypes at the regional and population level, (ii) assign ecotypes to germplasm pools and (iii) compare the relationship between German ecotypes and previously‐investigated European cultivars of perennial ryegrass, A total of 22 ecotypes originating from three geographic areas in Germany. each with a sample size of 20 individual plants, were investigated with 156 polymorphic RAPD markers. Genetic distance among ecotypes ranged from 0,27 to 0.48, An analysis of molecular variance (AMOVA) revealed a much larger variation within populations (71%) than among them (29%). Ecotypes from North Germany were significantly different from those of South and Middle Germany. Thus, two distinct germplasm pools could be identified. The 22 ecotypes and 22 previously investigated cultivars shared 98% of the molecular variance.     

Innovating in less developed regions: What drives patenting in the lagging regions of Europe and North America

Not all economically disadvantaged—“less developed” or “lagging”—regions are the same. They are, however, often bundled together for the purposes of innovation policy design and implementation. This paper attempts to determine whether such bundling is warranted by conducting a regional level investigation for Canada, the United States, on the one hand, and Europe, on the other, to (a) identify the structural and socioeconomic factors that drive patenting in the less developed regions of North America and Europe, respectively; and (b) explore how these factors differ between the two contexts. The empirical analysis, estimated using a mixed‐model approach, reveals that, while there are similarities between the drivers of innovation in North America's and Europe's lagging regions, a number of important differences between the two continents prevail. The analysis also indicates that the territorial processes of innovation in North America's and Europe's less developed regions are more similar to those of their more developed counterparts than to one another.     

Improving the productivity and profitability of irrigated rice production in Mauritania

Yield, input use, productivity and profitability of irrigated rice in Mauritania were analyzed during the 1997 wet season (July–December) in the Senegal river delta and middle valley, in collaboration with 42 large farmers and extension staff. Objectives were to determine agronomic constraints to rice cropping and to evaluate alternative crop management strategies aimed at overcoming these constraints. Grain yields ranged from 0.9 to 8.5 t ha⁻¹ and averaged 4.4 t ha⁻¹. Based on crop simulations, average yield potential in farmers' fields was estimated at 8.6 t ha⁻¹, indicating considerable scope for increased yields. Our survey identified the following main agronomic constraints: (i) mismatches between timing of nitrogen (N) fertilizer applications and critical N demanding growth stages of the rice plant; (ii) non-use of phosphorus (P) fertilizer on P deficient soils; (iii) largely neglected or inefficient weed management and (iv) late harvesting, often due to non-availability of combine harvesters. Based on these results we tested improved nutrient and weed management practices with farmers during the 1998 wet season. Improved nutrient management (i.e. T1: application of 20 kg P ha⁻¹ and 150 kg N ha⁻¹ in three splits at start tillering, panicle initiation and booting) increased yields by 0.9 t ha⁻¹. Improved weed management (i.e. T2: application of 6.0 L propanil ha⁻¹ and 2.0 L 2,4-d-amine ha⁻¹ at 2–3 leaf stage of weeds) also raised yields by 0.9 t ha⁻¹ as compared to farmers' practice (TP). The combined effect of T1 and T2 (i.e. T3) was additive: improving both nutrient and weed management raised yields by 1.8 t ha⁻¹ over average farmers’ yields of 3.9 t ha⁻¹, i.e. an increase of almost 50%. The improved crop management practices were highly profitable: compared to farmers’ practice, net benefits increased by 40% for T1 and T2 and by about 85% for T3, with minimal additive investments. Inputs used for T3 are relatively easily available in Mauritania. We concluded that increased farmer awareness of the profitability of improved nutrient and weed management may have a tremendous impact on the competitiveness of rice production in Mauritania     

Modelling productivity and resource use efficiency for grassland ecosystems in the UK

Estimating spatially resolved grassland productivity is essential for benchmarking the total UK productive potential to assess food, feed and fuel trade-offs in the context of whole systems analyses. Our objectives were to adapt and evaluate a well-known process-based model (PBM) and estimate productivity of improved (permanent, temporary) and semi-natural grassland systems using meta-models (MM) trained by extensive PBM scenario simulations. Observed dry matter (DM) yields in multi-site nitrogen (N) response (0, 150 and 300 kg N ha⁻¹) experiments were well emulated describing the average productivity of rough grazing, permanent and temporary grassland (3.1, 7.4 and 9.8 t DM ha⁻¹, respectively). Cross-validated with independent and long-term data (Park Grass Experiment), the PBM explained more variation when considering all systems combined (81%) than across all improved grasslands (61%) but little for rough grazing (26%). The PBM-trained MMs explained 48, 72 and 70% of the simulated yield variation in the grasslands of increasing management intensity, and 43 and 75% of observed variation in the combined improved and all three grassland systems, respectively. Considering the assessment of ecosystem services, like drainage and water productivity, PBM scenario simulations are essential. Compared to improved grassland rough grazing will result in 40% more groundwater recharge due to its lower simulated water use and water productivity (12 versus 25 and 43 kg ha⁻¹ mm⁻¹ for permanent and temporary grassland, respectively).     

Microsatellite markers: an overview of the recent progress in plants

In recent years, molecular markers have been utilized for a variety of applications including examination of genetic relationships between individuals, mapping of useful genes, construction of linkage maps, marker assisted selections and backcrosses, population genetics and phylogenetic studies. Among the available molecular markers, microsatellites or simple sequence repeats (SSRs) which are tandem repeats of one to six nucleotide long DNA motifs, have gained considerable importance in plant genetics and breeding owing to many desirable genetic attributes including hypervariability, multiallelic nature, codominant inheritance, reproducibility, relative abundance, extensive genome coverage including organellar genomes, chromosome specific location and amenability to automation and high throughput genotyping. High degree of allelic variation revealed by microsatellite markers results from variation in number of repeat-motifs at a locus caused by replication slippage and/or unequal crossing-over during meiosis. In spite of limited understanding of the functions of the SSR motifs within the plant genes, SSRs are being widely utilized in plant genome analysis. Microsatellites can be developed directly from genomic DNA libraries or from libraries enriched for specific microsatellites. Alternatively, microsatellites can also be found by searching public databases such as GenBank and EMBL or through cross-species transferability. At present, EST databases are an important source of candidate genes, as these can generate markers directly associated with a trait of interest and may be transferable in close relative genera. A large number of SSR based techniques have been developed and a quantum of literature has accumulated regarding the applicability of SSRs in plant genetics and genomics. In this review we discuss the recent developments (last 4–5 years) made in plant genetics using SSR markers.     

Plant Location Patterns in the European Automobile Supplier Industry

Motor vehicle and motor vehicle parts production tend to exhibit a strong degree of agglomeration. We estimate a location model utilizing detailed plant‐level data for over 1,700 European locations of the largest motor vehicle parts suppliers, as well as the location of all light vehicle assembly plants operational in 2010. This unique data set allows us to estimate a location model for the region at a significantly higher level of resolution than the previous literature. The results suggest that the main forces of agglomeration in the European auto supplier sector are highway access and the desire to locate near assembly plants as well as near other parts‐producing plants.     

Assessing the effects of the large-scale road construction on the ethnic disparities of accessibility in Tibet from 2010 to 2020

Tibet is the main consist of the Tibetan Plateau and also inhabited by minorities in China. How to promote its road accessibility and narrow the gap between different ethnic groups should draw more attention. This study analyzes both territorial accessibility (At) and potential accessibility (Ap) in Tibet from 2010 to 2020, as well as the disparities within and between main ethnic groups, exploring whether ethnic minorities undertook the accessibility disparity or loss. The findings are as follows: (1) At and Ap are characterized by a center-periphery structure with a remarkably improvement and spatial difference from 2010 to 2020. The disparity between counties tends to widen slightly, whereas the increment of At shows the opposite feature. (2) The Hui and Han ethnic groups enjoy better accessibility than Tibetans, and the other ethnic minorities have insufficient accessibility, though with prominent improvement. The disparity in At within ethnic groups is smaller but tends to widen; by contrast, that of Ap is larger but tends to narrow. The Hui ethnic group enjoys relative equal accessibility, which tends to be more so, while Tibetans face unequal accessibility with no obvious improvement. (3) The proportion of Tibetans is negatively correlated with the improved accessibility, but those of the other ethnic minorities are positively correlated with the increment of At, indicating that the accessibility improvement in Tibet tilts to the ethnic minorities in remote areas. The overall spatial disparities in accessibility in Tibet tend to widen, but this does not totally apply to those between and within ethnic groups. Nonetheless, the construction of transport infrastructure alone may not be able to achieve equality. Above results may provide reference for related research and policy making for remote and minority areas in China and other similar regions.     

Unveiling the local determinants of population growth in the European Union

This paper studies the population growth dynamics in European NUTS3 regions over the period of 2000–2015 and offers generalizable evidence on the main drivers of population change at this sub‐level of analysis, which is so far rather unexplored. Results obtained by means of a spatial Durbin model highlight the roles of economic and demographic regional conditions in shaping population dynamics and the minor role of geography and environmental conditions. The fact that geographical polarization of population is occurring, which might result in an increase in regional imbalances, calls for policy actions in mitigating this phenomenon.     

Exploring the natural variation for reproductive thermotolerance in wild tomato species

Climate change has become a serious threat for crop productivity worldwide. The increased frequency of heat waves strongly affects reproductive success and thus yield for many crop species, implying that breeding for thermotolerant cultivars is critical for food security. Insight into the genetic architecture of reproductive heat tolerance contributes to our fundamental understanding of the stress sensitivity of this process and at the same time may have applied value. In the case of tomato (Solanum lycopersicum), germplasm screenings for thermotolerance have often used yield as the main measured trait. However, due to the complex nature of yield and the relatively narrow genetic variation present in the cultivated germplasm screened, there has been limited progress in understanding the genetic basis of reproductive heat tolerance. Extending the screening to wild accessions of related species that cover a range of climatic conditions might be an effective approach to find novel, more tolerant genetic resources. The purpose of this study was to provide insight into the sensitivity of individual reproductive key traits (i.e. the number of pollen per flower, pollen viability and style protrusion) to heat-wave like long-term mild heat (LTMH), and determine the extent to which genetic variation exists for these traits among wild tomato species. We found that these traits were highly variable among the screened accessions. Although no overall thermotolerant species were identified, several S. pimpinellifolium individuals outperformed the best performing cultivar in terms of pollen viability under LTMH. Furthermore, we reveal that there has been local adaptation of reproductive heat tolerance, as accessions from lower elevations and higher annual temperature are more likely to show high pollen viability under LTMH.     

Total factor productivity and the factors of green industry in Shanxi Province,China

Based on industrial panel data from 11 prefecture-level cities in Shanxi Province from 2008 to 2016, two kinds of total factor productivity (TFP) are measured: With and without the consideration of environmental factors. The specific decomposition of TFP under these two conditions is then discussed. Finally, the factors of TFP are studied in a green industry context. The results indicate the following: (a) The TFP's annual growth rate considering environmental conditions is higher than that without such consideration; (b) if environmental factors are neglected, TFP improvements primarily depend on technological progress; (c) when considering environmental factors, both technological progress and improved technological efficiency promote the growth of green TFP (GTFP), but this still primarily depends on substantial technological progress, with an annual average growth rate that reaches 10.2%; and (d) among factors, the economic development level, degree of openness, and urbanization positively correlate with the GTFP, while the industrial structure and degree of informatization significantly and negatively correlate with GTFP.     

The Dynamics of Industrial Concentration in the Regions of the European Union

ABSTRACT The spatial distribution of manufacturing in the regions of the European Union over the period 1977–1999 is examined in this article, using a series of nonparametric instruments proposed within the framework of the economic growth literature. These enable us to overcome some of the methodological limitations of the studies of this issue that have appeared to date. The results obtained reveal an increase in geographic concentration in most industrial activities during the whole of the period considered, the relevance of which has been especially important coinciding with the progress made in the economic integration process currently underway in Europe. Indeed, the empirical evidence presented in this respect suggests that this trend will continue in the future. Additionally, the observed degree of intrasectoral mobility is relatively low. Nevertheless, these findings reveal that the probability of further growth or decline in a given sector within a particular region is greater in those areas with an intermediate presence of the sector in question.     

Exploring the Role of Calcium to Improve Chilling Tolerance in Hybrid Maize

Abiotic stresses, including chilling, impede the plant growth and development mainly by oxidative damage. In this study, seed priming with CaCl₂ was employed to reduce the damage caused by chilling stress in hybrid maize. Maize hybrid (Hycorn 8288) seeds were soaked in 50, 100 and 150 mg l⁻¹ (ppm) aerated solution of CaCl₂ for 24 h and dried. Treated and untreated seeds were sown at 27 °C (optimal temperature) and 15 °C (chilling stress) under controlled conditions. Seed priming with CaCl₂ significantly reduced the chilling damage and improved the germination rate, root and shoot length, and seedling fresh and dry weights. Activities of antioxidants, including catalase, superoxide dismutase and ascorbate peroxidase, were also improved. Soluble sugars and α-amylase concentrations determined as general metabolic indicators of stress were also increased by seed priming with CaCl₂. Priming also improved the performance of maize at optimal temperature. Maintenance of tissue water contents, reduction in membrane leakage and increase in antioxidant activities, and carbohydrate metabolism seemed to induce chilling tolerance by CaCl₂. Seed priming with 100 mg l⁻¹ CaCl₂ was the optimal concentration in improving the performance of hybrid maize both under optimal and stress conditions.     

贵州山地稻鱼共养循环生态农业体系模式探索

近年来,很多科研工作者根据各地区资源实际情况,研究创建了多种稻鱼共养循环农业模式,集成了关键技术,并示范推广应用,如浙江省青田县的稻-鱼、贵州省从江县的“稻-鱼-鸭”等多种循环农业模式,贵州、江西、福建、四川、广东、广西以及浙江等地都取得了不错的成绩。根据多年的实践经验制订了多项农业循环体系标准,在促进农业增产、农民增收方面取得了显著成效,为加快我国“三农”建设起到很大的助推作用。但是在贵州黔西南山地稻鱼共养循环农业体系还不常见,因此很有必要对贵州山地稻鱼共养循环农业体系模式进行探索,这是一种新型的共养循环农业体系,能解决老百姓的增收问题、农村过剩劳动力和农民就地就业问题,促进农户增收,为农村脱贫致富开辟出一条新途径。     

Migration regions and interstate labor flows by occupation in the United States

"This paper investigates the migration patterns of occupational groups [in the United States]. The results confirm previous analyses of the differences in movement behavior between occupations but, in addition, show that this variation is a function of the industrial sector of employment. The chief aim of the paper, however, is to uncover the geography of labor flows for different occupational groups using a principal components analysis of interstate flow matrices....Results indicate that migration regions vary by occupation and industry and we argue that these differences reflect job information flows and regional employment structure for various classes of labor." Data are from the Public Use Microdata Sample A taken from the 1980 census.     

沿海地区提高棉花春播育苗质量的措施

在棉花春播育苗工作中要坚持正确选种、安全下种、提高质量、育足壮苗的指导思想，围绕套栽棉４叶１心、麦后棉６叶１心的壮苗指标，狠抓关键和薄弱环节，提高春播育苗水平，为大田生产打好坚实的基础。１适期播种适期播种能充分利用有效的生长季节，播期的确定要根据当地气候回升情况和移栽时间而定，露地播种一般要求棉田土壤５cm处的温度稳定在１２℃以上，预计５～６天内不会显著下降，出苗时气温可达１６℃以上即可播种；塑膜营养钵育苗移栽一般要求５cm土壤稳定在８℃以上，气象预报有连续晴好天气的基础上抢晴播种。盐城地区春季气温…     

The benthic biological submodel in the European regional seas ecosystem model

The submodel describing benthic biology including a bioturbation module as incorporated in the European Regional Seas Ecosystem Model (ERSEM) is discussed. It is linked to a nutrient dynamic model. The structure of the benthic model food web is presented. There are four macrobenthic functional groups, meiobenthos and aerobic and anaerobic bacteria. The modelling uses ‘standard organisms’ as basic building blocks. The choice of parameter values is discussed. The results demonstrate the dependence of the benthic system on the pelagic system. The importance of features such as predation within functional groups for stability of the system is investigated. Detritus input from the pelagic system and detritus recycling is most important in the benthic food web. The web of carbon and nutrient fluxes through the system is analysed. On the basis of the food web analysis, the trophic positions of the functional groups are calculated. Besides the benthic biology, the mathematical formulation of the bioturbation and diffusion enhancement is discussed. Macrobenthic presence and activity enhance diffusion in the sediment and contribute essentially to vertical transport of particulate matter. This is of great importance for the vertical distribution of detritus, and as a consequence, for microbial activity in the sediment layers.