NANNING, May 29 (Xinhua) -- It is May and markets across China are bursting with durians, as it is peak harvest season across the Association of Southeast Asian Nations (ASEAN), the main exporter of this popular fruit. At Dongxing Port in Guangxi Zhuang Autonomous Region, south China, many durian stalls crowd both sides of the street, and the vendors' hawking fills the air. "This year, there are more varieties of durians for