China’s Vice President Xi Jinping , at center, attends an event at China Agricultural University in Beijing on Saturday. A man whose work is connected with the university took this photo and asked to remain anonymous for fear of angering the Chinese government. (Courtesy photo)

In an apparent move to quell swirling rumors about his health, Chinese Vice President Xi Jinping reappeared in public Saturday after mysteriously vanishing for two weeks, showing no outward signs of injury during a leisurely stroll on a university campus.

Although Xi, who is slated to become China’s new top leader this fall, appeared to be in relatively good health, his appearance left many questions unanswered. Xi had not been seen since Sept. 1 and had canceled several appointments with foreign leaders, spawning theories that he had suffered serious harm and raising the possibility that his health could jeopardize an upcoming leadership transition.

On Saturday morning, Xi arrived at China Agricultural University in Beijing to attend its celebration of “National Popularization of Science Day,” according to witnesses and a statement by the state-run Xinhua News Agency.

Xinhua also released two accompanying pictures of Xi.

In one, Xi was walking outdoors on what appears to be the university’s sunny campus, flanked by other officials who, like him, were wearing dark jackets. Xi’s smile and upright posture in the photo were notable in light of an especially pervasive rumor that Xi had injured his back. The second photo showed him gesturing while talking in front of a red table laid out with corn and plants at the agricultural university.

In recent days, speculation about what had happened to Xi, 59, had ranged from soccer- and swimming-related injuries to an attempted assassination by car crash. Most recently, how­ever, party officials and analysts with close ties to the party have been privately discussing two main possibilities: a back injury or a mild heart attack.

This week, one man — who, like Xi, is part of the group of children of revolutionary leaders commonly called China’s “princelings” — said Xi’s mother told a concerned visiting princeling that her son was not feeling well and was recovering from an injury to his lower back. The man spoke on the condition of anonymity because of the party’s current crackdown on discussions about Xi.

But one witness at Saturday’s event, who was able to maneuver within a few feet of Xi, said he looked perfectly fit. “He was very talkative and looked very healthy. I think all those rumors about him will be dashed.”

The man, a student at the agricultural university, spoke on the condition of anonymity for fear of angering the government. He said Xi’s visit lasted more than 30 minutes and included stops at booths showing crop and fish farming technology.

According to the student, Xi mentioned to onlookers how China’s main concern in the past was to “eat full” but is now to “eat well” and “eat healthy.” At one point, Xi saw a display on techniques to check melamine levels in milk — a source of some of China’s most serious recent food-safety scandals — and he praised the work.

The student and other witnesses said security around Xi was relatively loose, and some were able to take snapshots of Xi with their cellphones. In those photos, Xi also seemed to be walking around the science exhibition with ease.

Heavy censorship in recent days has squelched much of the online discussion. But Xi’s reappearance led to a small burst of chatter on the Internet, with many circumventing the restrictions by using nicknames such as “crown prince” to refer to Xi.

A message early Saturday with news about Xi’s reappearance was forwarded to 5,928 netizens within 50 minutes of being posted.

A campus blogger going by the handle DangqiHuichang2011 noted: “The library is closed and students have to stay in the dorm. The school is greeting the prince indeed!”

Despite Xi’s reemergence Saturday, the secrecy and feeling of crisis that had built up around him shows the need for greater transparency, many experts said.

In other countries, such public disappearances and reappearances would not be the focus of so much attention and rumors, noted Zhang Lifan, a historian who has studied the Communist Party. “It shows the system does need reform.”

In terms of internal politics, while Xi’s disappearance may have caused some worries within the party, it may also have helped him in an indirect way, Zhang said. “From the perspective of the political struggles, his disappearance is also a way of showing his importance in China’s political life,” Zhang said.

Although designed to end rumors, Saturday’s appearance sparked fresh speculations, as well. Some online users dissected Xi’s appearance, questioning for instance why he wore a jacket, given the day’s warmth and sun.

“Others just wore their shirt, but he wears a jacket. Is this because he just recovered from serious illness?” asked microblogger Gewensen.

“You got people so worried,” tweeted another blogger. “So what were you doing these past few days, Comrade Jinping?”

Wang Juan and Zhang Jie contributed to this report.