Rothamsted Symposium on Trace Elements 



F. Steenbjerg outlined the main problems of trace elements occurring 

 in Denmark and summarised some of the results of his extensive investiga- 

 tions, particularly those concerning copper. He emphasised, in particular, 

 the shape of the curve— which is 'S' shaped— relating dry matter production 

 of plants and their total copper content. 



M. LoHNis reported extensive data relating to the damaging effects on 

 Phaseolus vulgaris and other crop plants of excess manganese in acid soils, 

 and endeavoured to relate the susceptibility of crops to deficiencies and 

 excesses of the element to 'ease of absorption of manganese.' Difficulties 

 to this explanation are, however, presented by crops such as beans QPhaseo- 

 Zms) and strawberry. 



Extensive pot culture and field experiments on injurious factors in acid 

 soils have also been in progress at Long Ashton for a number of years. "^' 



The contribution of D. Mulder, presented by M. Lohnis, concerned 

 the occurrence of zinc deficiency in fruit trees in Holland, Hungary, Den- 

 mark and Switzerland. This deficiency has also been identified in fruit 

 trees, mainly apples, in several areas of England and seems to be a world- 

 wide problem in fruit crops, particularly Citrus and apples. 



Trace element problems, described by E. A. Jamalainen, are also of 

 great practical importance in Finland, especially deficiency of boron, which 

 presented very serious problems during the war when supplies of boron 

 could not be obtained from abroad. 



A point of particular interest is that boron deficiency in Finland occurs 

 on strongly acid soils, though the effects are, as usual, increased by liming. 

 Copper deficiency is also of importance, but manganese deficiency is of 

 very local occurrence due to the acid reaction of most of the Finnish soils. 



The paper of L. Seekles dealt with trace element problems of farm 

 stock. Though not direcdy concerned with plant physiology, this contri- 

 bution served to show the importance of plant nutrition studies in helping 

 to solve problems of animal and human nutrition. The similarity of the 

 patterns of the problems in plants and animals were obvious— the simple 

 deficiency, the 'conditioned' deficiency, the excess, the interactions, the 

 pathological symptoms and finally the role of the nutrients in the enzjmie 

 systems. The need for collaboration between plant and animal physiolo- 

 gists, to whom may also be added soil scientists and climatologists, is now 

 well recognised, and this coordination is of vital necessity to ensure the 

 progress that is needed to increase tbe world supplies of food sufficiently 

 fast to meet the needs of the rapidly expanding world population. 



References 



1. Symposia on Minor Elements, 1945: Soil Science 60. 



2. McCoUum-Pratt Institute, 1950: Symposium on Copper Metabolism (in 

 press ) . 



3. British Commonwealth Specialist Conference in Agriculture, 1949: Plant 

 and animal nutrition in relation to soil and climatic factors (in press). 



4. Nicholas, D.J.D., 1950: J. Hort. Sci. (in press). 



5. Anderson, A. J. and Oertel, A. C, 1946: Commonwealth of Australia 

 C.S.I.R. Bull. 198. 



6. Davis, E. B., 1945: Nature 156: 392. 



7. Jones, J. O., 1950: Ibid. 165: 248. 



8. Plant, W., 1950: Ibid. 165: 553. 



9. Bertrand, G. and D., 1950: C. R. 230: 343. 



10. Jones, H. E. and Scarseth, G. D., 1944: SoU Sc. 57: 15. 



11. QuASTEL, J. H., 1946: The Royal Inst, of Chemistry of Gt. Britain and 

 Ireland. Lecture on Soil Metabolism. 



12. Wallace, T., Hewitt, E. J. and Nicholas, D. J. D., 1945: Nature 

 156: 778. 



