问题
问答题 简答题
马铃薯喜欢酸性土壤吗？
答案
参考答案：
马铃薯是较喜酸的作物，土壤PH值在4.8-7.0的范围内生长都比较正常，但最适宜的土壤PH值在5.0-5.5之间。当土壤PH值小于4.8接近强酸性时，马铃薯植株叶色变淡，生长不正常，早衰，减产；当土壤PH值大于7.0时，碱性过大，会造成大幅度减产。
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马铃薯喜欢酸性土壤吗？
参考答案：
马铃薯是较喜酸的作物，土壤PH值在4.8-7.0的范围内生长都比较正常，但最适宜的土壤PH值在5.0-5.5之间。当土壤PH值小于4.8接近强酸性时，马铃薯植株叶色变淡，生长不正常，早衰，减产；当土壤PH值大于7.0时，碱性过大，会造成大幅度减产。
| About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen. The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots with organic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids. |
The underlined word "themselves" in Paragraph 1 refers to ______.
A．plant physiologists
B．solutions
C．laboratory flasks
D．roots