128 MASS. EXPERIMENT STATION BULLETIN 176. 



Standard nutrient solution. 

 With calcium carbonate. 

 With calcium sulfate. 



With 40 parts manganese per million of solution. 

 With 40 parts manganese and calcium carbonate. 

 With 40 parts manganese and calcium sulfate. 

 With 100 parts manganese per million of solution. 

 With 100 parts manganese and calcium carbonate. 

 With 100 parts manganese and calcium sulfate. 

 With 200 parts manganese per million of solution. 

 With 200 parts manganese and calcium carbonate. 

 With 200 parts manganese and calcium sulfate. 

 With 300 parts manganese per million of solution. 

 With 300 parts manganese and calcium carbonate. 

 With 300 parts manganese and calcium sulfate. 



The experiment was conducted outdoors in the pot yard instead of in 

 the greenhouse, the seedlings being put under cover at night and during 

 inclement weather. The experiment was continued four weeks. 



The effect of the manganese was noticed after the first week. The 

 seedlings with manganese did not grow as fast as the checks, and also 

 began to show chlorosis of the leaves. The roots did not have a stunted 

 appearance as was noticed when iron and alummium salts were used, but 

 seemed to be simply underdeveloped. Neither the presence of calcium 

 carbonate nor calcium sulfate had any beneficial effect. In some cases 

 the calcium carbonate seemed to aggravate the to.xicity rather than alle- 

 viate it. When the experiment was discontinued the tops in the most 

 concentrated manganese solutions had died and those in the most dilute 

 had apparently lost all their chlorophyl. 



The tops and roots of the plants were dried and manganese determina- 

 tions were made on them. The table shows the amounts of manganese 

 found in 1 gram of oven-dried samples. 



Table VI. — Milligrams of Manganese Oxide {MrizO^ in 1 Gram of Clover 

 Plants. 



Standard, 

 40 ppm Mn, 

 100 ppm Mn, 

 200 ppm Mn, 

 300 ppm Mn, 



The results show that manganese is taken up by the plants in consider- 

 able amounts and is carried into the tops. Concentrations above 100 

 parts of manganese per million of solution have little effect in increasing 



