托福阅读真题解析Word文档下载推荐.docx

1、植物通过感受不同光照事件长短，决定播种，科学家通过对叶子遮光处理，分为三种：不受光影响，长日照和短日照，检测植物的信号。但是最后还是没有收获，但是日照长短对植物的影响是明显的【重点词汇解析】sunlight 日光long-day 长日照short day 短日照plant 植物seed 种子signal 信号obvious 明显的【机经解析】光照长短对植物生长的影响Light duration or photoperiod refers to the amount of time that a plant is exposed to sunlight. When the concept of

2、photoperiod was first recognized it was thought that the length of periods of light triggered flowering. The various categories of response were named according to the light length （i.e., short-day and long-day）. It was then discovered that it is not the length of the light period but the length of

3、uninterrupted dark periods that is critical to floral development. The ability of many plants to flower is controlled by photoperiod.Plants can be classified into three categories, depending upon their flowering response to the duration of darkness. These are short-day, long-day, or day-neutral plan

4、ts. Short-day, （long nights） plants form their flowers only when the day length is less than about 12 hours in duration. Short-day plants include many spring and fall flowering plants such as chrysanthemum and poinsettia. Long-day, （short nights） plants form flowers only when day lengths exceed 12 h

5、ours. They include almost all of the summer-flowering plants, as well as many vegetables including beet, radish, lettuce, spinach, and potato. Day-neutral plants form flowers regardless of day length. Some plants do not really fit into any category but may be responsive to combinations of day length

6、s. The petunia will flower regardless of day length, but flowers earlier and more profusely under long daylight. Since chrysanthemums flower under the short-day conditions of spring or fall the method for manipulating the plant into experiencing short days is very simple. If long days are predominan

7、t, a black plastic sheet is drawn over the chrysanthemum for 12 hours daily to block out light until flower buds are initiated. To bring a long-day plant into flower when sunlight is not present longer than 12 hours artificial light is added until flower buds are initiated.Light DurationLight durati

8、on refers to the amount of time that a plant is exposed to sunlight. Travelers to Alaska often marvel at the giant vegetables and flowers that grow under the long days of the arctic sun even with cool temperaturesWhen starting transplants indoors, generally give plants 12 to 14 hours of light per da

9、y. Plant are generally intolerant of continuous light for 24 hoursPhotoperiodThe flowering response of many plants is controlled by the photoperiod （the length of uninterrupted darkness）. Photoperiod response can be divided into three types.Short day plants flower in response to long periods of nigh

10、t darkness. Examples include poinsettias, Christmas cactus, chrysanthemums, and single-crop strawberrieLong day plants flower in response to short periods of night darkness. Examples include onions and spinachDay neutral plants flower without regard to the length of the night, but typically flower e

11、arlier and more profusely under long daylight regimes. Day neutral strawberries provide summer long harvesting （except during heat extremes）光照长短对花期的形成和长短的影响Bougainvillea plants were exposed to artificially reduced light intensity to capture different Photosynthetic Photon Flux Density （PPFD）, 0% （di

12、rect sunlight）, 30, 50 and 75% shading and to observe the effects of shading on flower formation and longevity, leaf chlorophyll and sugar content and quality of plants. Plant attained the greatest leaf size with maximum branching when seedlings were grown in 30 and 50% shading, whereas 0% shading s

13、howed the lowest value. Growth parameters related to the plant characteristics such as branch initiation, branch growth and potassium content increased under high shading treatments. Plants exposed to 0% shade showed the highest sugar content and the sugar content decreased by increasing shading. Th

14、e low light intensity that results in decreased sugar and chlorophyll contents may be attributed to the reduction of flower initiation and in turn to the acceleration of flower abscission. In addition, more than 30% shading led to stop up flower initiation completely. Hence, it is suggested that 0%

15、shading can be applied to maintain frequent flower initiation and flower longevity.第二篇 英国农业的发展这篇阅读讲英国农业如何在欧洲其他各国的农业*之前独自发展至小康水平。 英格兰的农业比欧洲其他国家发展的都早都好，其他国家在大战或者有瘟疫的时候英格兰都没受太大影响。还说英格兰农场主发现农业获利很大后，就采取了高产的农产品，新技术，把原来tenure的农民都化成了签约式的，而且签约前要交钱否则就用别人（此处有题，大概是说四个选项里哪个没有在文中提到）。还说到由于农场主采用了嫡长子继承制，所以没有土地仍然很集中。还举例如提高房租，改善耕种方式，还有开始做羊毛，并且出口至欧洲各国甚至美国。agriculture 农业European 欧洲的England 英格兰development发展plague 瘟疫farm 农场benefit 利益new technology 新技术tenure 终身职位；任期；保有farmer 农场主the lineal primogeniture ,pra?mod?n?t? system 嫡长子继承制raise the rent 提高房租improve the cultivat