”The first generation of hybrid rice varieties are three-lines hybrids and produce yields that are about 15 to 20 percent greater than those of improved or high-yielding varieties of the same growth duration. ”[Food and Agriculture Organization, 2004].
Last 40 years rice crop was limited because of the self-pollination. Scientist intended to find a way which is improving rice crop. In 1974, Yuan long Ping is a scientist in China, he intended the first generation hybrid rice yields about 15-20 percent. In China hybrid rice area is 15 million hectare and accounted for about 50 present of the total rice area in 1995[Food and Agriculture Organization, 2004]. New generation of rice varieties of development of attract lots of attention, hybrid rice is one of them. Hybrid rice technology for large-scale production has a yield advantage of 15 to 20 percent, and more than one ton of per paddy hectare. Although Chinese paddy steadily reduced from 36.6million hectare in 1975 to 30 million hectare in 2000; the paddy reduced 0.6 present every year. China has been able to feed more than 1 billion people. The must important reason is hybrid rice to raise the national average yield from 3.5 ton/hectare to 6.2 …show more content…
The gas is colorless with a pungent odor readily detectable at concentrations as low as 0.02 to 0.05 ppm (by volume), which is below concentrations of health concern. Ozone gas is highly corrosive and toxic. Ozone is a powerful oxidant, second only to the hydroxyl free radical.”(Unites States Environmental Protection Agency,1999)Ozone as a strong oxidizer, have damage to a variety of tools, the higher the concentration of the tools will be heavier damaged, can make the copper appear green, rusty spot, rubber aging, discoloration, elastic, so that the brittle, fault, make the fabric bleaching faded. Ozone can irritate the human respiratory tract mucous membrane, 0.02 PPM, ozone concentration in the air can sniff out, up to 2.5 5 mg/L, can cause rapid pulse, fatigue, headache, if a man stay more than 1 hour, can happen emphysema, so that death.Therefore, ozone disinfection disinfection with air, must be under the condition of people not in, after disinfection at least thirty minutes before entering. Therefore the food industry use ozone irritate of place only have machine, machine will be heaver damaged by