1,721,165 research outputs found
Sustainable Potato Production Worldwide: the Challenge to Assess Conventional and Organic Production Systems
No full textSustainable agriculture integrates environmental health, economic profitability as well as social and economic equity. Worldwide interest in potato as a valuable food security crop is increasing, because it is not globally traded, the prices are determined by local production costs and due to its beneficial impact on human nutrition. In the present review, organic and conventional potato productions were assessed by means of key indicators for sustainability. These indicators were fertility management and crop protection, yield level, tuber quality and environmental impact. The evaluation of several studies shows that each system has advantages and disadvantages. None of the production systems is per se more sustainable than the other. Each of them has potential for improvement of the system performance. In organic production, for example, by establishment of improved fertilization (e.g., application of more N-efficient base organic fertilizers) and crop management strategies (e.g., pre-sprouting of seed tubers, bio-based fungicides), in conventional farming by implementation of more target-oriented fertilization and pesticide spraying schedules. To meet the future challenges with increasing food demand while simultaneously decreasing its environmental impact, efforts on increasing the performance of both conventional and organic production systems, e.g., improving the nutrient use efficiency, are necessary
Impacts of NaCl stress on plant growth and mineral nutrient assimilation in two cultivars of strawberry
No full textTwo strawberry (Fragaria x ananassa Duch.) cvs Korona and Elsanta differing in their tolerance to NaCl salinity were exposed to 40 and 80 mmol NaCl L-1 for over 4 months in the growing seasons of 2002 and 2003, respectively. However, the osmotic potential, i.e. the NaCl concentration of the root medium, varied during the experiments, because Hoagland solution and demineralized water were added usually once a week in order to push NaCl uptake on the one hand, but to allow leaching the soil after application of demineralized water on the other. Leaching the soil should quickly improve the water relations of the plant, but not affect salt levels within the plant. This strategy was chosen to reduce the effects of water stress and to focus onto the salt-specific impacts of NaCl stress. The salt stress reduced fresh and dry matter of the whole plants and photosynthetically active leaf area, especially in cv. Elsanta. Typical leaf symptoms of Na and Cl stress were detected in both cvs and the combined effects of both toxic ions resulted in the leaf scorching symptoms. Na uptake of both cvs was similar, but distribution of Na within plants was different. Korona was able to protect leaves more efficiently from Na accumulation. Under NaCl stress Korona plants achieved a significant increase of K content in leaves and crowns, while Elsanta showed an increase of K in fruits and petioles. The accumulation of K under evaluated NaCl levels suggests an efficient K uptake system in strawberry plants. Concentrations of Ca were not significantly affected, with the exception of rising levels in roots of Elsanta plants. Concentrations of Mg, Mn and Fe significantly decreased in leaves, while those of Mg and Mn remarkably rose in crowns of both cvs. N content in leaves, petioles, and roots of both cvs increased. In addition it rose in fruits and crowns in cv. Elsanta. A significant limitation of N uptake by competition with Cl did not occur in these plants. Concentrations of P increased in roots and petioles of both cvs, and in fruits of cv. Elsanta. With respect to Zn and Cu, significant concentration changes related to NaCl stress could not be detected. (C) 2008 Elsevier B.V. All rights reserved
Contribution of amino acids to strawberry fruit quality and their relevance as stress indicators under NaCl salinity
No full textStrawberry cvs Korona and Elsanta, differing in their sensitivity to salt stress, were exposed to 0, 40, or 80 mM NaCl in the root medium from the end of April to mid-August. Although fruits of both cultivars contained comparable amounts of Na+ and Cl−, fruit quality was more impaired in cv. Elsanta, as indicated by the larger reductions of fruit size and sugar/acid ratios. Malondialdehyde levels started to rise significantly at 40 mM NaCl in the more sensitive cv. Elsanta, but at 80 mM in cv. Korona. Total amino acid levels, especially contents of essential amino acids, rose significantly in both cvs. Salt stress also increased contents of free proline, asparagine, and glutamine. Their increases may contribute to osmotic adjustment. The results of the present study favour the interpretation that elevated levels of proline, asparagine and glutamine are indicative of salt stress damage
Influence of weather conditions on the activity and properties of alpha-amylase in maize grains
No full textCultivar-dependent cell wall modification of strawberry fruit under NaCl salinity stress
No full textStrawberry cultivars differ in their sensitivity to NaCl; fruits of cv. Elsanta suffer from softening, whereas those of cv. Korona retain their firmness. The mean fruit fresh weight is reduced in cv. Elsanta up to 46% and in cv. Korona up to 26%. Cell walls of fruits grown under 0, 40, or 80 mmol/L NaCl were extracted and analyzed. In fruits of cv. Korona, the content of the alcohol-insoluble residue remained comparatively stable as salt levels increased but was reduced in cv. Elsanta. The water-soluble pectin fraction was not affected in cv. Korona, but the content of low methoxy pectinates increased significantly, indicative of the generation of calcium and magnesium bridges that stabilize pectin polysaccharicles of cell walls. In cv. Elsanta, the content of water-soluble pectin rose, indicating pectin solubilization. For both cultivars, the significant negative correlation of fruit Cl- contents with the contents of NaOH-soluble pectinates, when expressed per fruit fresh mass, indicated that covalently bound pectic substances were degraded. Especially the response of cv. Elsanta is in line with the general observation that severe osmotic stress results in slower cell expansion and weaker cell walls
Apoplastic antioxidative system responses to ozone stress in strawberry leaves
No full textCell wall polysaccharides, pectin composition, as well as apoplastic superoxide dismutase and peroxidase activities were investigated in strawberry (Fragaria x ananassa) cultivars (cvs) Korona and Elsanta differing in their ozone sensitivity. Plants were exposed to 140-170 microg m(-3) ozone either short-term for 7 days or long-term for 2 months in order to investigate whether differences in ozone sensitivity were due to differences in the apoplastic antioxidative systems. Cell wall polysaccharides were increased after 7 days and 2 months of ozone stress. While water-soluble pectins, low methoxy pectinates and NaOH-soluble pectinates were elevated after 7 days, their contents were unaffected (water-soluble pectins) or lower (low methoxy pectinates, NaOH-soluble pectinates) after 2 months. In cv. Elsanta, ozone treatment resulted in a significant reduction of superoxide dismutase activity after 7 days and 2 months, while it remained similar in cv. Korona. After 7 days, peroxidase activity was significantly higher in ozone-exposed leaves of cv. Korona, whereas after 2 months it was similar to or higher than in controls. Superoxide dismutase in cv. Korona detoxified ozone and its products in the apoplast, and the resulting elevated levels of H(2)O(2) were balanced within 7 days by an increase in peroxidase activity. Long-term peroxidase activity may not play a comparably significant role in ozone defence, but the increase in cell wall polysaccharides and cell wall thickness measured after 2 months, resulting in a decrease in specific leaf area, reflected structural modifications that limited activities of reactive oxygen species efficiently. In contrast, the reduction of superoxide dismutase activity in cv. Elsanta indicated a less efficient apoplastic radical scavenging system, at least during the first 7 days of ozone stress, which was accompanied by membrane leakage and contributed to accelerated leaf senescence. Long-term, the reduction of intercellular air space volume in leaves contributed to ozone tolerance of cv. Elsanta as in cv. Korona
Modifications of strawberry fruit antioxidant pools and fruit quality under NaCl stress
No full textThe responses of fruit antioxidants in two strawberry cultivars differing in their sensitivity to NaCl stress were studied. The sensitive cv. Elsanta and the less sensitive cv. Korona were treated with NaCl solutions of 40 and 80 mmol/L in the nutrient solution. In general, moderate salinity resulted in increases of antioxidant capacity. In cv. Korona, salt stress increased the activity of superoxide dismutase and the contents of glutathione, phenols, and anthocyanins, while that of ascorbic acid decreased. In cv. Elsanta, changes of superoxid dismutase activity and of ascorbic acid concentration were comparable to those of cv. Korona, but the decrease of ascorbic acid was more distinct. The contents of anthocyanins decreased, and those of phenols remained similar. The glutathione content was reduced at the highest NaCl level. The results indicate that less salt-sensitive strawberry cultivars may be grown under moderate salinity stress to optimize fruit quality
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