Interaction of Mineral Deficiency and Nitrogen Source on Acid Phosphatase Activity in Leaf Extracts

Plants were grown in sand cultures to observe the effects ofmineral deficiencies, with different sources of nitrogen supply,on leaf acid phosphatase activity using phenolphthalein phosphateas substrate. Large increases ranging from 7 to 18 times normal (on freshweight or protein basis) occurred with deficiency of phosphoruswith nitrate, nitrite or ammonia nitrogen; increases from 4to 8 times normal occurred with deficiencies of zinc with nitriteor ammonia; and of copper with nitrite. Less pronounced increases,from 2 to 3 times normal on a protein basis, occurred with deficiencyof zinc with nitrate; of boron with all nitrogen sources; ofmanganese and of iron with nitrite. Activities on both proteinand fresh-weight basis were often greater with nitrite or ammoniumsulphate than with nitrate. Effects of phosphorus, zinc, copper,boron, and nitrogen sources were significant. Molybdenum deficiency caused approximately 2 times normal activityon a protein basis in tomato, tobacco, sunflower, cauliflower,lucerne, mustard, spinach beet, and lettuce when nitrate wasgiven. Effects with ammonia nitrogen were not consistent inmolybdenum-deficient plants but 50 per cent. increases occurredin the first 5 species listed. Activities varied widely betweenspecies. It was concluded that the increases in activity were causedby increases in amounts of the enzyme produced during growth,and that different combinations of deficiencies and nitrogensupplies produce different specific responses in terms of enzymesynthesis.