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Science:向日葵幼株为何向太阳

摘要 : 每天,年幼的向日葵们追随着太阳转动,就像在观看一场异常缓慢的网球比赛一样。

 

每天,年幼的向日葵们追随着太阳转动,就像在观看一场异常缓慢的网球比赛一样。但是,科学家们从来不知道这是为什么,也不知道为什么当它们长大后,这种“太阳跟踪”就停止了。现在,一项新的研究表明,这种每日的太阳崇拜是由向日葵发育过程中的昼夜节律引导的。在一系列的实验中,科学家们死死绑住向日葵幼株,阻止它们移动,或是在太阳升起的时候,把它们的花盘旋转到错误的方向。当这些植物的正常活动被阻扰时,它们的成长速度比普通向日葵要慢得多,生物量和叶面积均大约减少了10%。研究人员说,有规律的“太阳跟踪”帮助向日葵长得更大,让它们得以向那些进行“伸展”运动的侧面添加细胞:白天是东侧,晚上是西侧。研究人员在本周的《科学》杂志上报告说,当向日葵终于安定下来并停止这种每日跟踪时,它们的位置也给予其一个优势。第二组实验表明,成熟植物永远朝向东方,从而让花面更为温暖,这可能是授粉者的访问量增加的原因——比面朝西方的成熟植物多出五倍。看来追随太阳不仅仅只是一项具有观赏性的运动!

原文链接:

Why young sunflowers follow the sun

原文摘要:

Every day, young sunflowers follow the sun like spectators at an incredibly slow tennis match. But scientists have never known why, or why the tracking stops when they become adults. Now, a new study suggests that this daily sun worship is guided by circadian rhythms during development. In a series of experiments, scientists tied down young plants to prevent them from moving or rotated them so they were facing the wrong way when the sun rose. When the plants’ normal movements were thwarted, they grew far more slowly than regular sunflowers, with about a 10% decrease in both biomass and leaf area. Researchers say the rhythmic tracking helps the plants grow bigger, allowing them to add cells on whichever side is doing the “stretching”: the east side during the day and the west side at night. When the sunflowers finally settle down and stop this daily tracking, their position also gives them an advantage, researchers report this week in Science. A second set of experiments showed that mature plants’ permanent eastward orientation makes for warmer flower faces, which may be responsible for a large increase in pollinator visits—five times more than in mature plants that face west. Looks like following the sun is more than just a spectator sport!

来源: Science 浏览次数:0

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