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لماذا يتحول لون اوراق الشجر الى الاصفر,فأحمر,فبني في فصل الخريف؟

ج : اثناء الصيف تكون الاوراق منهمكه في صنع الطعام للشجره معتمده على مادة الكلوروفيل التي تمنحها الخضره . في الخريف تلتصق سيقان الاوراق ويتعفن الكلوروفيل وهكذا تخسر الاوراق لونها الاخضر وتنقلب الى صفراء او حمراء او بنيه قبل ان تسقط . حالما تسقط الاوراق تستريح الشجره الى الربيع القادم مستخدمه الطعام المخزون خلال الصيف . بعض الاشجار لاتفقد اوراقها وهي تدعى الاشجار الدائمه الخضره. معظم الصنوبريات اشجار دائمه الخضره.
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الكاتب: الادارة التاريخ: 2007/04/17
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