China In China, the mutant rice variety ‘Zhefu 802’ deriving from var. ‘Simei No. 2’, , induced by Gamma-rays, has a short growing period (105 to 108 days), high yield potential even under poor management and infertile conditions, wide adaptability, high resistance to rice blast, and tolerance to cold [5]. Therefore, it was the most extensively planted conventional rice variety between 1986 and 1994. Its cumulative planted area reached 10.6 million ha during that period [7]. Two other mutant rice varieties, Yuanfengzao (1970’s) and Yangdao # 6 (2000’s), developed and released before and after Zhefu 802, are further mutant varieties that had been grown on annual scales up to one million ha (Ministry of Agriculture, China, unpublished data). Using a pollen irradiation technique, two new high-quality, high-yield, and early maturity mutant varieties – Jiahezazhan and Jiafuzhan, resistant to blast and plant-hopper, as well as endued with a wide adaptability - were developed and are now planted annually on 363,000 ha in Fujian province of China [8].