Oct. i, 1920 



Cause of Lime-Induced Chlorosis 



43 



rice at this Station that the ratio of root to top growth was much increased 

 in calcareous soils and solutions (12, 17). The stimulating effect of car- 

 bonate of lime on the root growth of plants which are not calcifugous 

 has been frequently noted. 



In work with "pineapples it was shown that the alkalinity induced by 

 increasing amounts of carbonate of soda greatly depressed growth without 

 affecting the color of the plants (12, p. 31). 



Work with rice in water cultures seemed to show definitely that the 

 alkalinity of carbonate of lime is not directly injurious to this calcifugous 

 plant, nor is the alkalinity in itself the cause of chlorosis (17). Rice was 

 grown with different quantities of iron from different sources in nutrient 

 solutions which were acid, neutral, and alkaline from carbonate of lime. 

 A summary of the relative growths made under the different conditions 

 is given in Table VI. 



Table VI. — Relative growths of rice plants with different amounts of iron from various 

 sources in acid, neutral, and alkaline solutions 



Source of iron in nutrient solutions. 



Iron per 

 liter added 

 to nutrient 

 solutions. 



Relative growths in- 



Acid 

 solution. 



Neutral 

 solution. 



Alkaline 

 solution. 



Ferrous sulphate. 

 Do 



Gm. 

 o. 002 



Do 



Do 



Do 



Do 



Do 



Do 



Ferric chlorid. 



Do 



Ferric citrate. . 



Do 



Do 



Do 



Ferric tartrate. 



Do... 



Dialyzed iron. 



008 

 004 

 002 

 008 



1 002 

 008 

 002 



008 

 002 

 008 

 008 



100 

 100 

 100 



100 



100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 



74 

 95 



105 

 107 

 132 

 in 



99 



107 



85 



94 



101 



85 

 80 

 06 

 27 



5i 



95 



26 

 26 

 86 



97 

 104 



58 



76 



100 



Where growth was depressed to any extent the plants were more or 

 less chlorotic, and that this chlorosis was evidently due to lack of iron 

 was shown by analyses of the plants and by treatment of the leaves with 

 ferrous sulphate. The work showed quite definitely that rice is not 

 particularly sensitive to the reaction of carbonate of lime, except as the 

 reaction influences the availability of the iron. When the proper form 

 of iron was used in the proper quantity, the growth and appearance of 

 the plants were as good in the solutions containing carbonate of lime as 

 in the acid or neutral solutions. 



The preceding results seem to show that neither increased assimilation 

 of lime nor mere alkalinity causes chlorosis. It remained to be seen 

 187931°— 20 i 



