This paper reviews the knowledge on effects of climate change on agricultural productivity in Europe and the consequences for policy and research. Warming is expected to lead to a northward expansion of suitable cropping areas and a reduction of the growing period of determinate crops (e.g. cereals), but an increase for indeterminate crops (e.g. root crops). Increasing atmospheric CO2 concentrations will directly enhance plant productivity and also increase resource use efficiencies.
In northern areas climate change may produce positive effects on agriculture through introduction of new crop species and varieties, higher crop production and expansion of suitable areas for crop cultivation. Disadvantages may be an increase in the need for plant protection, the risk of nutrient leaching and the turnover of soil organic matter. In southern areas the disadvantages will predominate. The possible increase in water shortage and extreme weather events may cause lower harvestable yields, higher yield variability and a reduction in suitable areas for traditional crops. These effects may reinforce the current trends of intensification of agriculture in northern and western Europe and extensification in the Mediterranean and southeastern parts of Europe.
Policy will have to support the adaptation of European agriculture to climate change by encouraging the flexibility of land use, crop production, farming systems etc. In doing so, it is necessary to consider the multifunctional role of agriculture, and to strike a variable balance between economic, environmental and social functions in different European regions. Policy will also need to be concerned with agricultural strategies to mitigate climate change through a reduction in emissions of methane and nitrous oxide, an increase in carbon sequestration in agricultural soils and the growing of energy crops to substitute fossil energy use. The policies to support adaptation and mitigation to climate change will need to be linked closely to the development of agri-environmental schemes in the European Union Common Agricultural Policy.
Research will have further to deal with the effect on secondary factors of agricultural production, on the quality of crop and animal production, of changes in frequency of isolated and extreme weather events on agricultural production, and the interaction with the surrounding natural ecosystems. There is also a need to study combined effects of adaptation and mitigation strategies, and include assessments of the consequences on current efforts in agricultural policy to develop a sustainable agriculture that also preserves environmental and social values in the rural society. 相似文献
A series of field experiments was undertaken in order to determine whether resistance to bean common mosaic virus (BCMV) could be incorporated into genotypes of the common bean (Phaseolus vulgaris L.) suitable for cultivation in Zimbabwe without recourse to backcrossing. Six inbred genotypes carrying the resistance-conferring alleles at the loci I and Bc-3 were crossed with five locally-adapted inbred genotypes. The first experiment comprised F3 progeny rows, each derived from a single unselected F2 plant, the second, F3 bulks selected for resistance, and the third, a comparison of selected and unselected F2-derived F4 lines. The number of days to flowering and to maturity, the incidence of mosaic and necrosis symptoms, seed yield and seed size were recorded. There was evidence that late flowering and maturity were associated with BCMV resistance in some crosses, though not strongly enough to present an obstacle to plant breeding. The incidence of virus symptoms and seed yield were influenced by genetic factors additional to the major resistance genes, and variation in seed yield was present not only between bulk populations of crosses, but also between single-row plots of lines within crosses. This indicates that early-generation selection for yield in the presence of BCMV, even among progeny selected for BCMV-resistace, is likely to be effective. However, the variation in yield among F4 lines was least in the highest-yielding crosses, which may represent a limit to successful selection for yield. Seed size was partly under additive genetic control, but there was also evidence of non-allelic interactions. There was no association between large seed size, preferred by consumers, and susceptibility to BCMV in the progeny, indicating that the association between these characters in the parent lines is fortuitous and will not present an obstacle to plant breeding. It is noted that a considerable amount of useful genetic information can be obtained without recourse to elaborate crossing schemes, provided that unselected progeny are included in experiments as controls. The evidence presented indicates that resistance to BCMV can be combined with appropriate values of maturity date, yield and seed size without the need for backcrossing. 相似文献
This study aimed to investigate a cultivar selection criterion based on income ha−1 in common wheat. Regional yield trials with 20 entries were planted in Diyarbakır, Hazro and Ceylanpınar in southeast Anatolia in the 2004/2005 growing season. A randomized complete block design with four replications was employed. Grain samples from each location were subjected to quality analyses, and then presented to randomly selected grain purchasers with the local commodity market for market price estimations. Entries 1, 9, 10, 7 and 6 were the top five ranking entries for grain yield, giving 5,320, 5,290, 5,280, 5,140 and 5,130 kg ha−1, respectively. From the market price perspective, entries 17, 3, 7, 20 and 8 received the five highest marketing price offers with the values 239.0, 238.1, 237.1, 236.9 and 236.7 US$ tonne−1, respectively. There was a US$ 10.94 tonne−1 market price difference between entries with the highest and the lowest market price. The only quality analyses showing significant correlations with market price were Zeleny sedimentation value and hectolitre weights (kg hl−1). From thev production income [= marketing price (US$ tonne−1) × grain yield (kg ha−1)] point of view, entries 9, 10, 1, 7 and 6 were ranked from 1st to 5th for production income ha−1 with the values 1,241.0, 1,238.0, 1,219.9, 1,214.2 and 1,209.3 US$ ha−1, respectively. All five high yielding entries were also high-income entries. A rank stability analysis further indicated that entry numbers 6, 7, 8, 4 and 1 stable for high production income ha−1. A simulation study, based on allocation of additional premiums for high quality indicated that entries 9,1,10, 7, and 6 would be top ranking for high income ha−1 if given an additional premium of as much as twice the standard deviations of market price for each entry (the highest premium limit; 20.24 US$ tonne−1). The order for cultivar preference for high production income ha−1 would change and would generate 1,321.94, 1,296.20, 1,281.11, 1,258.06 and 1,243.01 US$ ha−1, respectively. It was concluded that the relatively quality conscious Şanlıurfa commodity market does not offer adequate premiums for the high quality grains. This results in farmer preference for high yielding lower quality cultivars. Even though quality cannot be neglected, and cultivar preference could change with additional premiums, breeders must give more attention to high production income ha−1. 相似文献
Growth trials were conducted outdoors in the UK to determine the yield, yield components and plant architectural differences
between determinate and indeterminate Phaseolus vulgaris bean plants. F3 lines derived from crosses between ‘Prelude’, a determinate cultivar and ‘V8’, an indeterminate landrace,
were grown together with the parents and ‘Carioca’, an indeterminate landrace from Brazil. Data were recorded on flowering
date, number of nodes on main stem at flowering, plant height at maturity, number of pods/plant, number of seeds/pod, number
of seeds/plant, 100-seed weight, seed mass/plant, percentages of diseased and healthy seeds/plant. Determinate F3 lines had
significantly lower (P < 0.05) seed mass/plant, fewer pods/plant, fewer seeds/pod, fewer seeds/plant, lower harvest index, shorter stems, earlier
date of flowering, fewer nodes at flowering and fewer healthy seeds/plant than indeterminate F3 lines. However, determinate
genotypes had significantly larger (P < 0.05) pods to accommodate their larger seeds compared with indeterminate lines. A similar situation was found when the
yield and yield components of ‘V8’, ‘Prelude’ and ‘Carioca’ were evaluated; the highest seed mass/plant was given by ‘V8’
and the lowest by ‘Prelude’. Furthermore, some indeterminate genotypes with Type IV growth habit yielded significantly higher
(P < 0.05) than the high-yielding parent, ‘V8’, indicating a positive influence on seed yield by crossing different genotypes. 相似文献
Summary The effect of a recurrent selection procedure for improving seed yield per plant was evaluated in common bean. Progress was registered after three cycles of recurrent selection with S2 progeny evaluation performed on the grain yield/plant. Gain from selection was estimated by field testing 45 random S2 lines from each of the C0, C1 and C2 populations. Response to selection for seed yield/plant was 6 g from C0 to C1 and 4.4 g from C1 to C2. The seed yield improvement was due principally to an increase in pods/plant; little contribution was provided by the 1000-seed weight and seeds/pod traits. Broad-sense heritability and genotypic variance for grain yield remained high in all cycles which suggests further gain from additional selection cycles. Grain yield/plant is significantly correlated to pods/plant and seeds/pod traits in all cycles, indicating that plants with favourable combinations of these traits could be identified. The proposed recurrent selection procedure appears to be effective in improving the population and extracting superior genotypes for varietal development. 相似文献
Summary Gene pyramiding in Phaseolus vulgaris is being utilized to develop more effective resistance to the temperature-insensitive-necrosis-inducing (TINI) strains of Bean Common Mosaic Virus (BCMV) present in the USA. Our data indicate that contrary to previous work, the bc-3 gene is effective against these strains in the absence of the strain unspecific bc-u gene in genotypes possessing the I gene. The epistatic bc-3 gene interferes with traditional efforts to pyramid the other recessive resistance genes by masking their activity. Indirect selection based on markers linked to the other recessive resistance genes would likewise be ineffective without the ability to also select for the bc-u gene which is required for expression of the bc-22 gene in germplasm carrying the I gene. Because the most resistant genotype (I, bc-u, bc-I2, bc-22, bc-3) can only be introduced into a wide range of germplasm through the use of molecular markers linked to the different resistance genes, the search for a marker linked to the strain unspecific bc-u gene should also be given priority. 相似文献