首页 | 本学科首页   官方微博 | 高级检索  
   检索      


SEASONAL VARIATIONS IN THE PROPORTIONS OF SUBERIZED AND UNSUBERIZED ROOTS OF TREES IN RELATION TO THE ABSORPTION OF WATER
Authors:Paul J Kramer  Henry C Bullock
Institution:Department of Botany, Duke University, Durham, North Carolina

Forest Service, Ocala, Florida

Abstract:Growing root tips usually constituted less than 1 per cent and mycorrhizal roots less than 6 per cent of the total root surface under a 34-year-old pine stand. Growing root tips usually constituted less than 1 per cent of the total root surface under a yellow poplar stand, although one sample taken in May contained 9 per cent of unsuberized roots. The water permeability of various types of roots was measured under a pressure gradient of 31 cm of mercury. It differed widely among individual roots, ranging from an average of 6.6. mm3/cm2/hr for suberized pine roots 1.33 mm in diameter, to 36.6 mm3 for suberized pine roots 3 mm in diameter, and 178 mm3/ cm2/hr for unsuberized roots grown in water culture. Water intake through a group of unsuberized roots grown in soil averaged 37.4 mm3/cm2/hr. The permeability of yellow poplar roots varied even more, ranging from essentially zero to 30,000 mm3/cm2/hr. It is concluded that the major part of water absorption in pine occurs through suberized roots, some through mycorrhizal roots, and relatively little through growing root tips. Likewise, in yellow-poplar most of the water probably enters through suberized roots. Further study is needed of the role of suberized roots in water and salt absorption.
Keywords:
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号