Browsing by Subject "Herbizidempfindlichkeit"

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Zur Diversität von Galium aparine L.-Herkünften
(2003) Ernst, Vera; Hurle, Karl
G. aparine is known as a very adaptable and worldwide distributed plant species. It is one of the worst weed species in numerous crops causing severe problems. Occasionally, a high degree of variability of G. aparine regarding to morphological and phenological characteristics was reported as well as to its herbicide susceptibility. Because of these observations and the necessity to gain more information about the biology and ecology of this species to perform a successful control of this weed in the field the variability of G. aparine was investigated. In comparative studies 24 field populations of different origins within Europe were used. For some of these populations the history of field management for the last few years was known. Additionally to the field populations one population from a hedgerow and one population of G. spurium has been further characterized. One central aim of these studies was the determination of the susceptibility of the populations against different herbicides. Furthermore the morphology and phenology of the different populations were also characterized. The variability of selected populations was examined by RAPD-PCR, too. The results of herbicide susceptibility tests showed that field populations of G. aparine reacted differently to the various herbicides. The largest differences in susceptibility were observed for the test herbicide, where one population showed a 6,8-fold higher tolerance than the most susceptible population (ED90). Low variability was detected for Mecoprop-P and Cinidon-ethyl, where populations differed at a factor of at most 1,5 and 1,7, respectively. Nearly all populations could be controlled with reduced herbicide concentrations compared to the recommended dosages. No resistant population was observed. Further, no significant differences between field populations and the hedgerow population could be detected. In several experiments the population of G. spurium tended to react slightly more susceptible towards the herbicides than G. aparine. A correlation between herbicide susceptibility and chemical control measures as described in the field history of the few past years could not be observed. The results with the test herbicide and Cinidon-ethyl might be interpreted as natural variability, because the active agents have not been on the market before sampling of the plants. Populations from adjacent fields showed as different susceptibilities as populations from distant fields, so that no regions with populations predominantly expressing significant levels of susceptibility or tolerance could be identified. The morphological and phenological tests showed that all populations differed regarding to many parameters. For most parameters the differences between the populations were in an identical range and persistently the populations differed at a maximum factor of 1,2-1,5. Higher differences than at this scale could be observed for the size of cotyledons, the number of seeds and the seminal yield. For the last parameter the largest differences could be observed with a maximum factor of 2,4 between the population with the smallest and highest seminal yield. Further, some populations showed a stronger habit than others. In a cluster analysis the G. aparine populations were divided into four groups. There was no difference between the field populations and the hedgerow population, but the population of G. spurium was, as expected, clearly different from G. aparine. An analysis of correlation revealed correlations for several parameters. For example, an early beginning of flowering was accompanied by a higher seminal yield. Some characteristics could furthermore be correlated with the geographic origin of the populations. Populations from northern and western locations often tended to have a less stronger habit than populations from the southern regions. Furthermore the onset of flowering was delayed compared to the populations from the more southern regions. The different characteristics could not been explained with the field history of the populations. Certainly the field history as well as climatic and geographic factors may have influenced the different morphology and phenology of the populations. In summary no morphological and phenological differences were detected between more sensitive or less sensitive populations. The results of the RAPD-PCR showed that 17 out of 40 tested primers were suitable to indicate polymorphisms between the different populations. They have been used to calculate the genetic similarity of the populations. The resulting genetic similarity of the G. aparine populations including the hedgerow population was between 93 and 97 %. G. spurium differed clearly from Galium aparine. No correlations could be detected between the results of the molecular and the morphological, phenological and herbicide susceptibility tests.