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Göttingen, Germany

Hoffmann C.M.,Institute of Sugar Beet Research
Journal of Agronomy and Crop Science | Year: 2010

Drought stress may affect sucrose accumulation of sugar beet by restricting leaf development and storage root growth. The objective of this study was to identify changes occurring in the storage root of Beta beets in growth characteristics and ions and compatible solutes accumulation under drought with regard to sucrose accumulation. Two pot experiments were conducted: (1) sugar beet well supplied with water (100 % water capacity), under continuous moderate (50 %) and severe drought stress (30 %), (2) sugar beet and fodder beet well supplied with water (100 %) and under continuous severe drought stress (30 %). Under drought stress, the ratio of storage root to leaf dry matter of sugar beet decreased indicating a different partitioning of the assimilates. The sucrose concentration of the storage root was reduced. In the root, the number of cambium rings was only slightly affected, although drought stress was implemented already 6 weeks after sowing. In contrast, the distance between adjacent rings and the cell size was considerably restricted, which points to a reduced expansion of existing sink tissues. The daily rate of sucrose accumulation in the root showed a maximum between 16 and 20 weeks after sowing in well-watered plants, but it was considerably reduced under drought stress. The concentration of compatible solutes (K, Na, amino acids, glycine betaine, glucose and fructose) decreased during growth, while it was enhanced because of drought. However, when sucrose concentration was added, a constant sum of all examined solutes was found throughout the vegetation period. It was similar in sugar beet and in fodder beet despite different concentrations of single solutes, and the total sum was not affected by water supply. A close negative relationship between the concentration of compatible solutes and sucrose occurred. It is therefore concluded that the accumulation of compatible solutes in the storage root of Beta beets under drought might be a physiological constraint limiting sucrose accumulation. © 2010 Blackwell Verlag GmbH. Source

Bornemann K.,Institute of Sugar Beet Research | Varrelmann M.,Institute of Sugar Beet Research
Phytopathology | Year: 2011

The genome of most Beet necrotic yellow vein virus (BNYVV) isolates is comprised of four RNAs. The ability of certain isolates to overcome Rz1-mediated resistance in sugar beet grown in the United States and Europe is associated with point mutations in the pathogenicity factor P25. When the virus is inoculated mechanically into sugar beet roots at high density, the ability depends on an alanine to valine substitution at P25 position 67. Increased aggressiveness is shown by BNYVV P type isolates, which carry an additional RNA species that encodes a second pathogenicity factor, P26. Direct comparison of aggressive isolates transmitted by the vector, Polymyxa betae, has been impossible due to varying population densities of the vector and other soilborne pathogens that interfere with BNYVV infection. Mechanical root inoculation and subsequent cultivation in soil that carried a virus-free P. betae population was used to load P. betae with three BNYVV isolates: A European A type isolate, an American A type isolate, and a P type isolate. Resistance tests demonstrated that changes in viral aggressiveness towards Rz1 cultivars were independent of the vector population. This method can be applied to the study of the synergism of BNYVV with other P. betae-transmitted viruses. © 2011 The American Phytopathological Society. Source

Reinsdorf E.,Institute of Sugar Beet Research | Koch H.-J.,Institute of Sugar Beet Research
Agricultural and Forest Meteorology | Year: 2013

The cultivation of sugar beet as a winter crop in Central Europe will require tolerance of severe frost. Due to the large variation of survival rates in different environments it is necessary to quantify the risk of frost killing for potential growing regions. The objectives of our study were, (i) to determine the lethal temperature of sugar beet taproot crown tissue as an indicator of frost damage, (ii) the development of a regression model that properly estimates the temperature of crown tissue from standard weather data, and (iii) a risk assessment for frost killing in four beet cultivation regions, representing different climatic conditions in Central Europe. In field trials at six environments, temperatures were measured above the beet canopy (0.3-0.5. m height), at the soil surface, 5. cm deep in the soil, and in the taproot crown. Survival rates were determined after winter.The survival rates of sugar beets were highly dependant on the maximum taproot diameter (optimal size: 1-2.5. cm) and the environmental conditions. A crown tissue temperature below -6. °C was a reliable indicator for frost killing, even though the exact lethal temperature of optimal sized sugar beets could not be identified. The crown temperature was accurately predicted from available weather data using multiple linear regression models. It was estimated best by combining the parameters 'daily mean air temperature', 'daily mean soil temperature at 5. cm depth' (closest correlation to crown temperature) and 'daily snow depth'. The prediction was further improved by adding the air and soil temperatures of the previous day and the 2-fold interactions of regressors to the model.Risk assessment for frost killing in Central European beet growing areas was based on weather data of the past 20 years provided by Germany's National Meteorological Service (Deutscher Wetterdienst, DWD). Our approach showed that at locations with mild winters, such as Cologne, the successful cultivation of winter sugar beet is possible with little risk of frost killing. On the contrary, growing winter sugar beet at places like Göttingen and Regensburg holds a high risk for frost killing. Finally, the presented approach needs to be improved with more accurate estimates of crown tissue temperature, and more precise determination of the lethal temperature of winter beets with the optimal taproot diameter. © 2013 Elsevier B.V. Source

Loel J.,Institute of Sugar Beet Research | Hoffmann C.M.,Institute of Sugar Beet Research
Field Crops Research | Year: 2014

The cultivation of sugar beet as a winter crop harvested in autumn of the next year is expected to contribute to a marked yield increase. Sown in autumn the plants have to survive frost during the winter. The study thus aimed to characterize the optimal growth stage, in which maximum winter hardiness is reached, and to determine the lowest temperature sugar beet plants can survive in this optimal growth stage. Furthermore, the importance of weather conditions (temperature, snow) in relation to the growth stage of the plants was assessed with a PCA (principle component analysis).From 2009 to 2012 field trials with 5 genotypes at 3 locations in Germany were conducted, which were accompanied by greenhouse experiments with controlled frost experiments. The survival rate after winter was mainly affected by the environment (year. ×. location, 93%), while the genotype effect (1%) was rather low. An optimal growth stage for maximum survival was determined at a thermal time after sowing of 600-900. °Cd (base temperature 3. °C). The greenhouse experiments revealed that in this optimal growth stage the plants survived a minimum temperature of -7. °C (-6. °C to -8. °C). In the field trials, the impact of the growth stage reached before frost (46%) on the survival rate after winter was considerably higher than the actual weather conditions during winter (17%). In particular too much advanced growth (dry matter yield of root and leaves, root diameter) resulted in a high susceptibility for frost damage. Regarding the weather conditions, the number of frost days with snow and the minimum temperature during winter without snow had the highest importance for survival.The knowledge of the required thermal time to reach maximum winter hardiness can be used to optimize the sowing date of autumn sown beets in different environments. However, a conflict may occur between the aim to obtain optimal winter hardiness and to reach maximum yield in the next year. © 2014 Elsevier B.V. Source

BACKGROUND: Resistance of Chenopodium album to triazinones and triazines can be caused by two amino acid exchanges, serine-264-glycine (Ser264Gly) and alanine-251-valine (Ala251Val), in the chloroplast D1 protein. This paper describes the identification of a biotype with a leucine-218-valine (Leu218Val) switch found in German sugar beet fields with unsatisfactory weed control. A greenhouse experiment has been performed to compare the resistance profile of the newly identified biotype with biotypes that carry the Ser264Gly and Ala251Val mutations. RESULTS: Application rate-response curves obtained from the greenhouse experiment showed that the Leu218Val exchange induced significant resistance against the triazinones but not against terbuthylazine. The level of resistance against the triazinones was higher in the Ser264Gly and Ala251Val biotypes compared with the Leu218Val biotype. All biotypes tested were more resistant to metribuzin than to metamitron. Following terbuthylazine treatment, Ser264Gly displayed a high level of resistance, Ala251Val showed moderate resistance. A PCR-RFLP assay for Ser264Gly has been extended to include detection of Ala251Val and Leu218Val mutations. CONCLUSION: The D1 Leu218Val substitution in C. album confers significant resistance to triazinones. This suggests that Leu218Val is involved in the binding of triazinones. First establishment of the resistance profiles of the three psbA mutations suggests that these mutations have been independently selected. © 2013 Society of Chemical Industry. Source

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