856 



SCIENCE 



[N. S. Vol. XLIV. No. 1146 



The chlorotic pineapples in Hawaii occur 

 on acid or neutral soils that average 5.0 per 

 cent. Mn s 4 and 0.5 per cent. CaO. 2 The 

 chlorotic pineapples in Porto Eico occur on 

 soils containing from 2 to 80 per cent, car- 

 bonate of lime and no manganese. That the 

 chlorosis in Porto Eico is induced by the car- 

 bonate of lime was proved by direct experi- 

 ment. Soils which normally produced healthy 

 pineapples were made to produce chlorotic 

 plants by the admixture of carbonate of lime 

 from different sources. 3 We may thus speak 

 of one as a manganese-induced chlorosis and 

 the other as a lime-induced chlorosis. 



The lime chlorosis was shown to be due to 

 a lack of iron in the plant, caused by the car- 

 bonate of lime diminishing the availability 

 of iron in the soil. At first it was not known 

 whether the chlorosis was due merely to a 

 lack of iron or to a lack of iron combined with 

 a large amount of lime in the plant. Eecent 

 work seems to show that it is merely due to a 

 lack of iron. 



Now the manganese chlorosis may be similar 

 to the lime chlorosis if the manganese acts 

 similarly in merely diminishing the avail- 

 ability of iron in the soil. The recent dis- 

 covery of Johnson shows that this may be pos- 

 sible. Previous work by Kelley, 4 and Wilcox 

 and Kelley 5 suggests, however, that the man- 

 ganese chlorosis may be more complicated. 

 In the work of these investigators there is 

 some evidence of a direct toxic effect of the 

 manganese, although they do not ascribe the 

 chlorosis to this. It is possible that the man- 

 ganese chlorosis is due to a deficiency of iron 

 combined with a direct toxic effect of the 

 manganese. Prom the results so far obtained 

 it can not be said whether the two kinds of 

 chlorosis are essentially the same. Certain 

 differences in the appearance and behavior of 



s Kelley, "W. P., Hawaii Agr. Exp. Sta. Press 

 Bull. No. 23. 



a Gile, P. L., Porto Eico Agr. Exp. Sta. Bull. No. 

 11, 1911. 



* Kelley, W. P., Hawaii Agr. Exp. Sta. Bull. No. 

 26, 1912. 



s Wilcox, E. V., and Kelley, W. P., Hawaii Agr. 

 Exp. Sta. Bull. No. 28, 1912. 



pineapples affected with manganese and lime 

 chlorosis give reason for supposing the two 

 forms may be more or less distinct. 



The manganese plants are described as 

 having roots with swollen tips and a generally 

 poor root system, while the lime plants have 

 good root systems, differing from normal 

 plants only in the roots being longer. 



In the development of " manganese yellows " 

 a purplish color is spoken of as preceding the 

 yellowish-white. This purplish color was not 

 observed in the lime-induced chlorosis, al- 

 though leaves sometimes had red splotches. 



The manganese chlorosis is described as 

 being most intense during the winter months 

 when we may assume normal plants were 

 growing less rapidly. The lime-induced chlo- 

 rosis we found to develop fastest in plants 

 growing most rapidly and to be more intense 

 the more sunlight they received. 



The application of ferrous sulphate to the 

 leaves apparently has a more permanent effect 

 on the manganese plants than on the lime 

 plants. Prom the reports so far it appears 

 that a few sprayings permanently cure the 

 " manganese yellows," while application of 

 iron salts to pineapples, rice, or sugar cane 

 affected with lime-induced chlorosis effects 

 only a temporary cure. Eepeated trials showed 

 that the treatment must be made frequently 

 to maintain the plants in a green and vigorous 

 condition. With rice growing on a strongly 

 calcareous soil it was necessary to spray six- 

 teen times with ferrous sulphate to maintain 

 a normal growth. This difference in the 

 amount of treatment necessary to cure the two 

 forms of chlorosis may merely indicate a dif- 

 ference in the extent to which manganese and 

 carbonate of lime depress the availability of 

 iron. 



The differences pointed out lend ground for 

 supposing that manganese chlorosis may be 

 due in part to a deficiency of iron in the plant, 

 induced by the action of manganese in the 

 plant or in the soil, and in part to a direct 

 toxic action of the manganese. Lime-induced 

 merely the result of a lack of iron in the 

 plant, due to carbonate of lime diminishing 

 the availability of iron in the soil. It is of 



