Super space seeds
Since humans sent the first satellite（卫星）to space in the 1950s, scientists have been studying an important topic：how to grow food in space if humans will one day live there. A recent experiment（实验）at the Tiangong space station makes a big step forward.
Chinese astronauts have successfully grown rice seedlings（幼苗）during the Shenzhou XIV mission. "The rice seedlings are growing very well, " said Zheng Huiqiong, a researcher from the Chinese Academy of Sciences. Since the rice experiment began on July 29, the seedlings of the tall shoot rice variety（高杆水稻品种）have reached a height of 30 centimeters. The seedlings of the dwarf rice variety（矮杆水稻品种）have grown to 5 centimeters, China Daily reported on Aug 30.
While there have been other rice experiments in space, this one is the first of its kind to produce the complete life cycle of a plant—it begins with a seed and ends with a mature（成熟的）plant producing new seeds.
Such food—growing experiments are not just for astronauts. They can also solve food problems on Earth. By sending seeds to space, we can create mutated（突变的）seeds, thanks to microgravity（微重力）, lack of air and cosmic rays（宇宙射线）. The seeds can then produce higher yields（产量）on Earth.
For more than 30 years, China has developed over 260 new types of seeds in space. They are planted every year in fields that cover tens of millions of hectares（公顷）.
According to Yao Tong, an engineer from Hainan Aerospace Engineering Breeding Research Center（海南航天工程育种研发中心）, 30 percent of strawberries sold in Beijing are "space strawberries", which are as big as eggs. The center has also produced "space tomatoes" with yields increased by 30 percent, and "space bananas" with a growth cycle（生长周期）shortened from 13 months to 9 months.
a. To feed astronauts.
b. To study microgravity.
c. To increase yields on Earth.
d. To research on cosmic rays.
