The economic significance of boron (B) in agriculture, horticulture, and forestry has been beyond dispute for several decades. Even in the last two decades, the areas where B deficiency limits plant production has grown with increased reports from China, south Asia and southeast Asia. The present volume is reflective of the growing awareness of the significance of low soil B with reports from Australia, Bangladesh, Brazil, north, central and southern China, India, Nepal, and the North West Frontier Province of Pakistan contained herein. Boron deficiency also continues to be a problem for crop yield and quality in areas where B deficiency has been known for some time, for example in Germany and the USA. The problem of low soil B is not limited to effects on field crop yield, with papers reporting on depressed wood yield and quality in timber trees (Lambert et al. ), and depressed fruit quality (Dong et al. ; Smith et al. : Zude et al. ) also appearing in the present volume. Globally, Shorrocks (1997)1 estimates that ?? tonnes of B fertiliser is applied annually in agriculture. The economic benefits from the use of B fertiliser have not been quantified but are clearly enormous. Paradoxically, the clear economic imperatives for using B fertiliser on low B soils are not matched by a similar clarity of understanding of the role and functions of B in plants.

This book is intended to bring together the contributions of many years of investigations from a number of laboratories involved in the systematic investigation of mother-offspring interactions and the attendant conse quences for development. A similar book (Rheingold, 1963) is now more than a decade old. The value of such a book is attested to by the burgeoning interest in the subject matter since the publication of that earlier volume. The importance of the mother-infant dyad has been recognized by scientests and parents alike since time immemorial. Pioneering writers such as Sigmund Freud, with his emphasis upon the expression of biological "needs" by the developing infant, and John B. Watson, with his emphasis upon the mother's role as a conditioner-trainer of her offspring, have been followed (in time, not emphases) by such investigators as Konrad Lorenz, with his now classic studies of imprinting, Jean Piaget's sequential analyses of the development of intellect, and Harry Harlow's ingenious studies of attach ment. The present volume reflects the influences of these earlier investigators. It is comparative, psychobiological, and represents a blend ofthe "experimental" approach characteristic of those trained in experimental psychology and the "natural history" approach more often represented in the work of ethologists. Sequential analyses of developmental changes in the mother-offspring relationship characterize virtually all of the work reported herein."

This symposium on 'Boron in Soils and Plants' completes a quartet of reviews of the behaviour in soils and plants of four trace elements, copper, manganese, zinc and boron, selected for their importance in agriculture. The series had its genesis in a suggestion from Professor Robin Graham of the Waite Agricultural Research Institute that it would be appropriate in 1981 to celebrate the Golden Jubilee of the publication in 1931 of the first definitive evidence for the essentiality of copper in plants. The previous decade had seen a resurgence of interest in copper deficiency and toxicity in agriculture and an expansion of our understanding of the behaviour of copper in soils and plants. We therefore decided to promote a review of our understanding of the behaviour of copper in soils and plants by inviting appropriate authors to prepare reviews of 14 topics for publication in a book and presentation at a Golden Jubilee International Symposium on 'Copper in Soils and Plants'. Posters of current research were also displayed and published. Murdoch University, Perth, Western Australia was chosen as the venue because of its then current research on copper, the importance of copper in Western Australian agriculture, and the presence in Perth of many international nutritionists due to the fortuitous scheduling in 1981 of the 'Fourth International Symposium on Trace Element Metabolism in Man and Animals'.

The Boron '97 meeting was a great success in summarising all recent developments in basic and applied research on boron's function, especially in plants. New techniques have since been developed and new insight has been gained into the role of boron in plant and animal metabolism. Nevertheless, there were still lots of open questions. The aim of the present workshop held in Bonn as a satellite meeting to the International Plant Nutrition Colloquium was thus to gather all actual information which has been gained since the Boron '97 meeting and to compile knowledge, both from animal and plant sciences. Furthermore, applied aspects had to be addressed too, as there is an increasing awareness of boron deficiencies even in crops such as wheat, which have formerly not been considered as responsive to boron application. Genetic differences in boron demand and efficiency within one species are a further important topic which has gained importance since the 1997 meeting. More in-depth knowledge on the mechanisms of boron efficiency are required as an increased efficiency will be one major possibility to maintain and improve crop yields for resource-poor farmers. Nevertheless, it has also clearly been shown that an adequate supply of boron is needed to obtain high yields of crops with a high quality, and that a sustainable agriculture has to provide an adequate boron supply to compensate for inevitable losses through leaching (especially in the humid tropics and temperate regions) and for the boron removal by the crop.

The Boron '97 meeting was a great success in summarising all recent developments in basic and applied research on boron's function, especially in plants. New techniques have since been developed and new insight has been gained into the role of boron in plant and animal metabolism. Nevertheless, there were still lots of open questions. The aim of the present workshop held in Bonn as a satellite meeting to the International Plant Nutrition Colloquium was thus to gather all actual information which has been gained since the Boron '97 meeting and to compile knowledge, both from animal and plant sciences. Furthermore, applied aspects had to be addressed too, as there is an increasing awareness of boron deficiencies even in crops such as wheat, which have formerly not been considered as responsive to boron application. Genetic differences in boron demand and efficiency within one species are a further important topic which has gained importance since the 1997 meeting. More in-depth knowledge on the mechanisms of boron efficiency are required as an increased efficiency will be one major possibility to maintain and improve crop yields for resource-poor farmers. Nevertheless, it has also clearly been shown that an adequate supply of boron is needed to obtain high yields of crops with a high quality, and that a sustainable agriculture has to provide an adequate boron supply to compensate for inevitable losses through leaching (especially in the humid tropics and temperate regions) and for the boron removal by the crop.