PREFACE 



The variety of mineral salts which plants require for growth are 

 taken up from the soil, or in the case of some aquatic plants, from 

 the surrounding water. The mechanism of absorption has been 

 extensively investigated during the past 30 years, and although it 

 cannot be said that the process is entirely understood, much 

 information has been obtained. This monograph is an attempt to 

 summarize present knowledge and ideas for the benefit of students 

 and research workers in the field of mineral nutrition. 



The subject is discussed against its historical background 

 (Chapter 1), proceeding from an account of experimental materials 

 and methods (Chapter 2) to a description of the physico-chemical 

 processes by which ions move in non-living systems (Chapter 3). 

 A summary of the effects of various external and inherent factors 

 on the course of absorption (Chapter 4) is followed by a consider- 

 ation of the relationship between uptake and metabolism (Chapter 

 5). The location of accumulation mechanisms in cells is discussed 

 in Chapter 6, and this leads to an account of salt absorption and 

 transport in vascular plants (Chapter 7). Finally, there is a brief 

 description of the soil as a source of mineral nutrients (Chapter 8) 

 and a discussion of the physiology of salt tolerance (Chapter 9). 



My heartfelt thanks are due to Professor T. A. Bennet-Clark, 

 F.R.S., who has given me unstinted advice and encouragement in my 

 investigations of salt absorption during the past 10 years. He read 

 a draft of the manuscript for this book and made valuable sug- 

 gestions for its improvement. The blame for any deficiencies or 

 errors that remain is of course entirely my own. My thanks are also 

 due to Professor F. C. Steward, f.r.s., for the benefit of many 

 stimulating discussions during my tenure of a Rockefeller 

 Foundation Fellowship at Cornell University in 1956-57, when 

 many of the data upon which the text is based were compiled. I 

 am grateful to Mrs. D. Howarth for her care in typing the 

 manuscript, and to my wife, Janet, for assistance in the preparation 



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