Castro was the starting catcher for the West team in Saturday night's Rising Stars Game, a showcase of the top players in the AFL that was broadcast on MLB Network and simulcast on MLB.com.
"After talking to the staff and spending the week in Arizona, we feel it's time for Jason to rest and focus on the 2010 season," Astros assistant general manager and director of player development Ricky Bennett said in a statement. "Jason has made tremendous progress throughout his first full season of professional baseball.
"From a developmental standpoint, he's done everything we've asked of him every step of the way, both offensively and defensively."
A non-roster invitee to Spring Training for the Astros, Castro started the season in Class A Lancaster, where he hit .309 with seven home runs and 44 RBIs in 56 games before being promoted to Double-A Corpus Christi. While there, he batted .293 in 63 games and was named to Team USA for the XM Futures All-Star Game in St. Louis, where he hit a three-run homer.
In September, Castro played for the Team USA squad that went 14-1 and captured the gold medal in the International Baseball Federation World Cup. Then, in October, Castro, the Astros' first-round pick in the 2008 First-Year Player Draft, joined the Peoria Saguaros in the AFL, for whom he went .143 (6-for-42) in 11 games.
Alden Gonzalez is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.