Zoomlion is the second-largest construction equipment maker in China, with 32,000 employees and reported revenue of 48 billion yuan ($7.6 billion) last year. The Hunan provincial government owns one-sixth of the company and is its largest shareholder. Calls to Zoomlion's press office in Changsha rang unanswered.
Police in the Hunan provincial capital, Changsha, said on its official microblog that the journalist had been detained on Saturday for alleged "damage to business reputation."
The newspaper adopted a slightly mocking tone in its plea: "If the heavens would give us a chance, then we would say: Uncle policemen, Brother Zoomlion, we beg you, release Chen Yongzhou!"
Chen is the second New Express reporter to be detained in recent months. In August, New Express reporter Liu Hu was detained after he made posts on his personal microblog urging authorities to investigate the deputy director of the State Administration for Industry and Commerce, saying that the official had been derelict while working in Chongqing.
Rights activists have decried the prosecution of Liu and others who have drawn attention to official or corporate misdeeds, saying they contradict the Communist Party's stated determination to root out corruption.
"Their detentions are bound to send a message to other journalists in China that the high-profile 'anti-corruption drive' championed by the new leadership does not welcome the voices of these independent whistleblowers," said Human Rights Watch Asia researcher Maya Wang.