ABSTRACT
A decision support system, SBN-Watch, was developed to demonstrate the influence of crop rotation and the choice of sugar beets (Beta vulgaris) varieties on the sugar beet cyst nematode Heterodera schachtii Schmidt (SBN) population and sugar beets yield. The database in SBN-Watch consists of a varietal unit with five sugar beet varieties representing the three categories "Standard," "Tolerant" and "semi-tolerant." Data of minimal yield (m), tolerance limit (T), and population dynamic parameters were obtained from published commercial field trials conducted in Sweden and Denmark in 2011. Additionally, a sanitation intercrop unit with different resistant classes of white mustard (Sinapsis arvensis) and oil seed radish (Raphanus sativus) was included. The relationship between initial population (Pi) and sugar yield as well as SBN final population in soil (Pf) was calculated by two Seinhorst equations. Few data inputs are required to be entered by the user in SBN-Watch, mainly the initial population (Pi), expected sugar price and exchange rate of to SEK. The calculated reproduction factor (Rf) values using SBN-Watch corresponded well with varietal characteristics, where the standard variety Mixer had the highest (Rf) values. The influence of the initial SBN population on the calculated sugar yield (tonnes ha-1) was generally small at Pi < 2.A decision support system, SBN-Watch, was developed to demonstrate the influence of crop rotation and the choice of sugar beets (Beta vulgaris) varieties on the sugar beet cyst nematode Heterodera schachtii Schmidt (SBN) population and sugar beets yield. The database in SBN-Watch consists of a varietal unit with five sugar beet varieties representing the three categories "Standard," "Tolerant" and "semi-tolerant." Data of minimal yield (m), tolerance limit (T), and population dynamic parameters were obtained from published commercial field trials conducted in Sweden and Denmark in 2011. Additionally, a sanitation intercrop unit with different resistant classes of white mustard (Sinapsis arvensis) and oil seed radish (Raphanus sativus) was included. The relationship between initial population (Pi) and sugar yield as well as SBN final population in soil (Pf) was calculated by two Seinhorst equations. Few data inputs are required to be entered by the user in SBN-Watch, mainly the initial population (Pi), expected sugar price and exchange rate of to SEK. The calculated reproduction factor (Rf) values using SBN-Watch corresponded well with varietal characteristics, where the standard variety Mixer had the highest (Rf) values. The influence of the initial SBN population on the calculated sugar yield (tonnes ha−1) was generally small at Pi < 2.
ABSTRACT
Bacteria belonging to the genus Methylobacterium are characterized by being able to rely on methanol as a sole carbon and energy source and by presenting a more or less intense pink reddish pigmentation. These bacteria, also referred to as pink-pigmented methylotrophic bacteria (PPFMs), are common inhabitants of the phyllosphere and are found in many other environmental samples. Since they grow slowly they are often overlooked and their impact on phyllosphere microbial communities and on the plants harboring them is not well studied nor has their ecology been elucidated. In a survey of PPFM colonization in three different agricultural sites, PPFM populations were identified on both red clover and winter wheat, but red clover was more consistently colonized. Isolations from collected leaves showed PPFM populations to decrease from spring towards summer, but they increased again towards the end of the cropping season. Isolates from red clover readily colonized winter wheat leaves and vice versa in greenhouse experiments, but population sizes were dependent on the application procedure. Tested isolates had also good potential to colonize the rhizosphere, especially after seed inoculations. Confocal scanning laser microscopy showed gfp-tagged isolates to colonize the surface of clover leaves by forming large aggregates.
