PORT Adelaide has re-signed youngsters Dougal Howard and Riley Bonner until the end of 2019, in the latest of a spate of contract extensions for Power players. 

Versatile tall Howard has made six appearances for Port since his debut in round two last season.

The 21-year-old hasn't cracked a senior appearance this year coming back from a knee reconstruction, but has a bright future at Alberton. 

"He's done everything right through his rehab and really offers us some versatility," forwards coach Brendon Lade said.

"'Doogs' can kick a bag up forward or give us some height down back, and even pinch-hit in the ruck if need be.

"He's showing a lot of promise."

Howard was taken with pick 56 in the 2014 NAB AFL Draft, while Bonner arrived at the club from West Adelaide via pick 37 the following year.

Bonner, who made his debut towards the end of last season against Gold Coast, has also spent this year playing exclusively in the SANFL but the 191cm defender is showing promise at state league level.

"Riley has shown in his first two years that he has the work ethic to get the best out of himself," defensive coach Nathan Bassett said.

"He has good speed and agility while showing that he can be a very good user of the football.

"I believe that Riley has considerable upside and that his best football will come in the not too distant future."

Earlier on Wednesday, the Power confirmed AFL.com.au's story from last week that backman Dan Houston had re-signed for two years until the end of 2019. 

Houston, Bonner and Howard follow Sam Powell-Pepper, Billy Frampton, Brad Ebert, Jack Hombsch and Tom Clurey in re-committing to the club recently.