GUANGZHOU, April 22 (Xinhua) -- The total output of industrial enterprises above designated size in Guangdong Province grew by 6.5 percent year-on-year in the first quarter, the highest in nearly nine months, said the provincial statistics bureau Sunday. The southern province's gross domestic product reached 2.39 trillion yuan (356.5 billion U.S. dollars) in Q1, a year-on-year increase of 6.6 percent, said Wang Liying, an official with the bureau. High-tech manufacturing industry recorded the highest growth rate of 9.6 percent, accounting for nearly one-third of Guangdong's total industrial added value. Private enterprises contributed to nearly 85 percent of the province's value added of the industrial enterprises above designated size, with a growth rate of 11.5 percent. Measures of tax cuts and fee reductions began to pay off in Guangdong and gave a strong boost to the market confidence in Q1, said Wang. Guangdong continued to see double-digit growth in investment in Q1, a rise of 11.2 percent. Investment in sectors including education, information transmission, software and information technology all grew by over 45 percent.