Solr have the SnowballPorterFilterFactory that you can use with a language parameter
<filter class="solr.SnowballPorterFilterFactory" language="Portuguese" />
Solr also have some language specific stemmers like the PortugueseStemFilterFactory. I have read the documentation but I am unable to find out what the difference between them are.
From the source comments:
Portuguese stemmer implementing the RSLP (Removedor de Sufixos da Lingua Portuguesa) algorithm. This is sometimes also referred to as the Orengo stemmer.
The algorithm used is specifically tailored to the necessities of the Portuguese language, and know about the different word classes and how they should be stemmed in Portuguese.
The Snowball stemmer however is a general stemmer engine, where you give it a dictionary to work with - i.e. suffixes that should be stemmed, etc. These does not allow the same kind of knowledge about how to classify and stem specific word classes.
I can't see any reason why you'd want to use the Snowball version when you have the Portuguese RSLP available, but I haven't done any work in Portuguese (I did however have to manually update the Norwegian one for certain edge cases that Snowball didn't catch by default).