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托福阅读例文翻译解析：矿物质和植物

2015-01-15 17:39:34来源：网络

　　2015年托福考试已经开始，对于每一位参加托福考试的同学来说都是新的开始，那么我们对于托福听说读写都需要采取怎样的复习方法?这四项又需要注意些什么呢?我们分别谈一下。下面是新东方在线托福小编整理的托福阅读例文翻译解析：矿物质和植物，供同学们参考!

托福阅读例文翻译解析：矿物质和植物

　　Research has shown that certain minerals are required by plants for normal growth anddevelopment. The soil is the source of these minerals, which are absorbed by the plant withthe water from the soil. Even nitrogen, which is a gas in its elemental state, in normallyabsorbed from the soil as nitrate ions. Some soils are notoriously deficient in micro nutrientsand are therefore unable to support most plant life. So-called serpentine soils, for example, aredeficient in calcium, and only plants able to tolerate low levels of this mineral can survive. Inmodern agriculture, mineral depletion of soils is a major concern, since harvesting cropsinterrupts the recycling of nutrients back to the soil.

　　Mineral deficiencies can often be detected by specific symptoms such as chlorosis (loss ofchlorophyll resulting in yellow or white leaf issue), necrosis (isolated dead patches),anthocyanin formation (development of deep red pigmentation of leaves or stem), stuntedgrowth, and development of woody tissue in an herbaceous plant. Soils are most commonlydeficient in nitrogen and phosphorus. Nitrogen-deficient plants exhibit many of thesymptoms just described. Leaves develop chlorosis; stems are short and slender, andanthocyanin discoloration occurs on stems, petioles, and lower leaf surfaces. Phosphorus-deficient plants are often stunted, with leaves turning a characteristic dark green, often withthe accumulation of anthocyanin. Typically, older leaves are affected first as the phosphorusis mobilized to young growing tissue. Iron deficiency is characterized by chlorosis betweenveins in young leaves.

　　Much of the research on nutrient deficiencies is based on growing plants hydroponically, that is,in soilless liquid nutrient solutions. This technique allows researchers to create solutions thatselectively omit certain nutrients and then observe the resulting effects on the plants.Hydroponics has applications beyond basic research, since it facilitates the growing ofgreenhouse vegetables during winter. Acroponics, a technique in which plants are suspendedand the roots misted with a nutrient solution, is another method for growing plants withoutsoil.


本文关键字: 托福阅读例文翻译解析 矿物质和植物

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