As English is not my mother tongue, i have difficulties to find some items one 
the net via search engines like for exaample news.google.com.
I write for German newsletters about renewable resources like hemp, flax and so 
on.
If i search via news.google.com about the nice yelow crop rape I only find 
thousants of websites about rape. If I type in "rape +oil" ore rape +farm ore 
even rape oil, there are only hits about raped patrol stations or farms.
Coult your give me a hint, which key word I shoult use in order to find 
something about the oil producing crop rape?

The problem you are having is a very common problem even without language 
difficulties. Certain words have multiple meanings, and certain names are used 
to refer to unrelated entities. The best way to sort out undesired "hits" from 
the ones you want is to force the inclusion or exclusion of related or 
unrelated words that may appear on the pages. Fortunately, Google provides good 
tools to help sort out the results you want in this way. You can find good help 
on advanced search features for Google at:

://www.google.com/help/refinesearch.html

If you are unfamiliar with advanced search techniques, Google also provides a 
friendly interface to help you construct such a search:

://www.google.com/advanced_search

Often, the best way to approach a problem like yours is to first do the search 
with no advanced features. Even though you really want to search 
news.google.com, you may find it easier to refine your search on general 
websites first, since there are more of them. In this case, search on "rape":

://www.google.com/search?q=rape

Most of the "hits" are unrelated to your subject. Look at a few of these pages 
and identify other words which frequently 
appear: "sex," "sexual," "abuse," "man," "woman," "women." You can exclude 
these in your next search:

://www.google.com/search?q=rape+-sex+-sexual+-abuse+-man+-woman+-women

Now, sites involving the plant are starting to appear. You could keep going by 
adding more words to exclude, but you get diminishing returns, and you may run 
up against Google's 10-word search limit. Rather, it is time to look at the 
good hits to look for words that always appear: "oilseed," "seed," "plant." You 
could force inclusion of all of them, but, in this case, only one might appear, 
and none of these words are likely to appear in undesired sites, so an "OR" 
operation is the best way to go:

://www.google.com/search?q=rape+-sex+-sexual+-abuse+-man+-woman+-women+%
2Boilseed+OR+%2Bseed+OR+%2Bplant

Finally, shift over to the news.google.com:

http://news.google.com/news?as_q=rape+-sex+-sexual+-abuse+-man+-woman+-women+%
2Boilseed+OR+%2Bseed+OR+%2Bplant

The search now looks like it gives you only what you want! By experimenting 
with searches in this way, refining them as you go along based on the results 
you get, you should be able to construct an effective advanced search without 
having to know or guess the right words to include or exclude up front.
Good luck with your searches!

excellent. thank you very much for your help!

I believe that the name "rapeseed" refers to the same plant / crop you're 
looking for.  Try searching for that instead.

Rapeseed is also called "canola". Try searching for that.

Try searching for 'canola'. That's the name used for this crop in Australia.