Browsing by Person "Kruse, Michael"

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    Der Einfluss von Ölgehalt und Fettsäuremuster auf die Lagerfähigkeit von Saatgut
    (2007) Ghiasvand Ghiasi, Kambiz; Kruse, Michael
    Seed storage with the objective of maintaining the quality for the later sowing is a constant challenge, not only in gene banks but also in agriculture, forestry and horticulture. In 1980 ELLIS and ROBERTS established ?The improved seed viability equation? for the prediction of the storability of seeds. With this equation the loss-of-germination-curve can be computed as a function of the initial seed germination, the storage temperature and the seed moisture content for each species. However, with oil-rich seeds the equation very often misses its aim. With this seeds, the variety and lot specific oil content considerably determines water activity and aging rate. Therefore the objective of the present work was to describe the influence of oil content on the aging behavior of seeds of the oil crops during storage quantitatively, to integrate this influence in the most reasonable way into the viability equation and to improve accuracy of its prediction. The investigation was carried out with storage experiments under controlled conditions in the laboratory at higher temperatures and running times between a few days and six months. First it was examined, whether the usually determined oil content of the entire seed is an informative parameter for water activity in the embryo axis. Experiments with sunflowers with an oil content between 28 and 48 % showed that oil-rich seeds need an about 1 % higher seed moisture content than seeds with lower oil content to have the same water activity in the embryonic axis. The storage of these seeds as well as the seeds of rape with oil contents between 39 and 50 % and flax with oil contents between 36 and 43 % showed that the loss of germination is more consistent with uniform water activity than with uniform seed moisture content. This has not been taken into account in the previous viability equation, so that its prediction contains systematic errors. Therefore extensive storage experiments were carried out with altogether 28 seed lots of rape, sunflower, flax and corn with different moisture contents and a uniform temperature of 45°C. Only for few of the stored lots the prediction of the seed viability equation was found to be correct. To include the oil content into the seed viability equation eight different suggestions were compiled. These were applied in three nonlinear regression models with different restrictions to the results of the storage experiments. The first model permitted the species specific determination of the weighing factors (constants) for the seed viability equation. The second model only allowed to determine the weighing factors for the absolute term and the seed moisture content specifically. Oil content was provided however with a species-nonspecific weighing factor. In the third model all weighing factors were species-nonspecific determined. All eight suggestions achieved better estimations for the aging rate in the species-specific models than the previous viability equation. Where this could be examined statistically, the improvements were significant. The same was found for the models with species-nonspecific weighting factors for the oil content. However, not all suggestions led to a converging result of the regression analysis. All examined species-nonspecific models did not improve the adjustment compared to the previous viability equation. The suggestions were then validated with a new and independent dataset with a storage temperature of seeds of 32°C. It was shown that the change of the temperature reduced the accuracy of the estimations of the nonlinear regression models. The new suggestions nevertheless corresponded better to the observed results than the previous viability equation. Based on these results a suggestion was then selected for the extension of the viability equation by ELLIS and ROBERT, which does not introduce a new weighing factor to the equation as the weighing factor might potentially contribute to a decrease of the precision of a prediction due to its standard error. Finally it was examined whether the fatty acid composition before storage in addition to the oil content affects the aging rate and whether the change of the fatty acid composition is directly connected to the loss of germination during storage. Only with rape, significant relations between the proportion of the fatty acid 14:0, 18:0, 20:0, 22:0 and the aging rate of the seed lots were determined. A uniform change of the fatty acid composition of all examined species could not be observed. Therefore this characteristic could not contribute to the further improvement of the prediction accuracy of the seed viability equation. To summarize, a suggestion to include the oil content into the viability equation was designed that clearly improves the accuracy of the prediction of the viability equation for oil-rich seeds and that contributes to a more appropriate and efficient storage of seeds.
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    Inhomogenität in Getreidesaatgutpartien : Ursachen und Konsequenzen für die Saatgutprobenahme
    (2009) Schmohl, Sven; Kruse, Michael
    The objective of this research was to quantify inhomogeneity and evaluate its formation in cereal seed lots. The results were used to compile proposals for a better in seed sampling schemes and to give recommendations to avoid inhomogeneity formation during seed processing. For this purpose, the extent and structure of the variation in the seed quality criteria, purity, other seed count, germination, thousand seed mass and size grading were determined within seed lots as well as their change during seed processing. Commercial seed lots of oat, wheat and barley were sampled from the delivery point to the bagging of the lots. All primary samples, in total 1944, were analyzed separately. The evaluation of the inhomogeneity was done by either an H-test or a R-test according to the ISTA rules. Additionally, for each seed quality criteria at each station of seed processing the results of the primary samples were analysed by means of regression analyses to detect systematic gradients. From a total of 57 stations, 56 showed significant inhomogeneity in at least one seed quality criteria. There were significant differences between the seed quality criteria and the crop species in terms of composition as well as extent of inhomogeneity. In the unprocessed seed lots the proportion of stations with significant inhomogeneity were between 14 and 100 % for thousand seed mass, 33 and 100 % for germination, 50 and 100 % for size grading, 57 and 100 % for purity and between 0 and 75 % for other seed count. After cleaning, the proportion of stations with significant inhomogeneity were between 17 and 55 % for size grading, 14 and 100 % for thousand seed mass, 0 and 43 % for purity and between 50 - 67 % for germination. During the seed processing the initially stochastic dispersion of the seed quality criteria size grading and purity at the delivery point were increasingly replaced by systematic gradients. In case of thousand seed mass, systematic gradients were already present at the delivery point. However, the determination of the observed gradients increased during the processing. In the processed seed lots the seed quality criteria thousand seed mass and purity with 74 % and 72 % respectively showed most frequently systematic gradients at the sampling stations, followed by seed grading with 59 % and germination with 29 %. Other seed count showed rarely systematic gradients with less than 5 % of the stations. In the processed seed lots the systematic gradients entailed inhomogeneity in up to 100 % of the stations for germination, in up to 60 % for thousand seed mass and in up to 33 % for size grading and purity. In the case of other seed count the systematic gradients did not cause inhomogeneity, however for the most part because the lots were almost free from other seeds. The main reasons for the formation of gradients, and thus for the formation of inhomogeneity, are segregation effects in combination with core flow during filling and discharging silos. Additionally, in the case of the germination the mechanical load of the seeds during the processing is an important factor for the formation of inhomogeneity. Therefore, besides the use of suitable conveying devices and the limitation of lot size, the use of suitable silos in respect to the prevention of core flow and the evasion of unnecessary interim storage are important steps for the avoidance of inhomogeneity. The frequent occurrence of systematic gradients in processed and unprocessed seed lots recommends a systematic or stratified sampling scheme. In case of systematic sampling the primary samples are drawn in constant time intervals. In case of stratified sampling the primary samples have to be drawn within constant periods of time, whereas the time within the intervals is at random. These sampling schemes and the random sampling scheme were evaluated in computer simulations in terms of their accuracy and efficiency. The simulations were using the data collected from the cereal seed lots. The systematic and the stratified sampling of only 10 primary samples results in the same accuracy of the submitted sample as 30 primary samples collected at random according to the present ISTA rules. In case of interference between the systematic and stratified sampling scheme and the systematic gradients, a further decrease of the number of primary samples could lead to a strong impair of the accuracy of the submitted sample. Therefore in terms of these sampling schemes a further reduction of sampling intensity is not advisable. On the basis of the results obtained from commercial seed lots produced in one seed processing plant of one enterprise, inhomogeneity and its causes in cereal seed lots could be studied in detail. From the experimental data of commercial seeds lots conclusions for the further improvement of sampling procedures could be compiled.
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    Langzeitlagerung von Saatgutproben in „ultra dry seed storage“ zur Lagerung pflanzengenetischer Ressourcen in Genbanken
    (2011) Yang, Qi; Kruse, Michael
    The conservation of plant genetic resources through seed storage in gene banks is primarily restricted to relatively short lived plants with orthodox seeds, to which most agricultural and horticultural species belong. Their storage properties are influenced by two key factors, seed moisture content and storage temperature. Ultra-dry seed storage follows the theory that drying seeds to sufficiently low moisture contents could achieve successful long-term seed storage even at room temperature. The artificial freezing storage of seeds, which is usually used in modern gene banks, would not be required. This is very attractive for the gene banks in developing countries where energy supply is limited. The following questions are still remained to be answered for the realization of ultra-dry seed storage. - Will the seeds be damaged by drying close to 0 % moisture content? - Is there for ultra-dry seed storage optimal moisture content (OMC) or optimal relative humidity (ORH) as well as a respective upper and lower limit above 0%? - If such upper and lower limits exist, are they identical among species? - How good is the storability of the seeds under ultra-dry conditions? Does the improved seed viability equation of Ellis and Roberts (1980) also apply to the ultra-dry region? Seed samples of the four breed lines HR2203, HR2632,HR2660 and HR2693 of rape seeds (Brassica napus L.), the three cultivars Naturastor, Tomi and Triso of wheat (Triticum aestivum L.) and the two cultivars Giugenese and Sturo of onion (Allium cepa L.) were used. The moisture contents (MC) of onions, rape seed and wheat were adjusted separately to 39 different levels from near 0 % to 7 % in sealed desiccators with silica gel (r.H. close to 0 %) or in the fine-drying chamber (r.H. about 10 %) of the gene bank at IPK-Gatersleben. The dried seed samples were sealed individually in aluminum foil to keep the MC. The equilibrium relative humidity was determined after 14 days by using a metal thread sensor. Sorption isotherms were created according to these data. The wheat and the rape seed samples were then stored at 50 °C for about one year and eight months, respectively. The onion seeds were stored at room temperature for about one year and subsequently stored at 50 °C for up to three months. The germination and seed vigor tests were performed during storage. The experimental results reveal that the Henderson model fits the experimental moisture sorption data better than the modified GAB and Chung-Pfost equation and is therefore suggested for modeling the correlation between the equilibrium moisture content and the relative humidity in ultra dry region. The germination and seed vigor tests indicate that the seed storability increases along with decreasing seed moisture contents till an optimum is reached. There is clearly an optimum seed moisture content (OMC) for the ultra-dry seed storage, below which the storability decreases significantly. The OMC for storage at 50 °C are 4 % and 3.1 % for rape seeds breed lines HR2203 and HR2632, 2.3 % and 2.0 % for the wheat cultivars Naturastor and Triso, as well as 1.9 % and 1.5 % for the onions cultivars Giugenese and Sturo. The corresponding optimum relative humidity (ORH) in balance are 42 %, 22 %, 11 %, 6 %, 1 % and 3 %, respectively. The OMC for the storage of onion cultivars Giugenese and Sturo at about 20 °C are 2.7 % and 1.9 %, and the corresponding ORH are 2 % and 5 %, respectively. Thus, the OMC and ORH are not only species specific, but also cultivar- and possibly also seed lot-specific and temperature dependent. The improved seed viability equation can be used to describe the seed storage behavior above the OMC adequately. The seed storage behavior below the OMC could be described with polynomials. Based on the obtained data it is not possible to give a general recommendation for upper and lower limits of the seed moisture content or relative humidity for a successful ultra dry storage. The storage property of rape seed stored at OMC is better than those of wheat and onion seeds; although under normal conditions the storability of wheat is better than that of the other two species. Calculated from obtained data rape seed with 99 % initial germination lost only 0.14 % of germination during one-year storage at 50 °C. Contrary to the hitherto conventional evaluation of the storage behavior of seeds, the experimental results showed that the temperature and seed moisture content do not affect storage property of seed independently and their effects cannot be offset against each other in the ultra dry region. Extrapolated to the ultra-dry seed storage at ambient temperature in a gene bank it can be assumed that the seed can be stored safely for at least 3 years. Longer storage is possible, but it is required to keep the seed of different species, cultivars and even seed lots at their specific OMC. The separate determination of OMC for all accessions in a gene bank is practically difficult to carry out. Thus, it is recommended for long-term storage in gene banks to store seed samples at appropriate low seed moisture contents from 1.5 % to 4.0 % and under cool conditions as a precaution.