32 



WHEAT RESISTANCE TO TOXIC SALTS. 



phate than is scKliuiii siil])hat('. They foiiiul dial tlio resistance of 

 sodium siilj)hate was raised (U) times by adding calcium sul])hate. 

 In the light of these facts it is easy to accept Stewart's residts. In 

 tact. Kearney and Cameron showed that when other saHs were added 

 the limit for Liiptmi.^ allnix in sodium sulphate could be raised to 

 ().;^0 of a nornuil solution, and that for sodium chloi-id only to 0.>J(), 

 while in pure solutions the limit for sodium sulphate was a concentra- 

 tion of 0.0075 and for sodium cldorid 0.02. This also explains Hil- 

 gard's results as to the comparatixe harmlessness of sodium sulphate 

 in the soil where other salts are always present. 



RESULTS WITH SODIIM CirLOKU). 



The results obtained by the writer Avitli pure solutions of sodium 

 chlorid are shown in the folloAvinc table: 



Maximum limit of 

 eudurance. 



Name of wlieat variety. 



Zimmerman 



Kliarlcof 



Padui _ 



Kubanka 



Turkey 



Maraouani _ 



Budapest _ 



Preston ,. 



Chul 



Average for all varieties _. 



Parts per Fractional 



100,000 

 of solu- 

 tion. 



part of a 



noi'iiial 



solution. 



377 

 319 

 333 

 333 

 290 

 319 

 275 

 319 

 261 



314 



0.065 

 .055 

 . 0575 

 .0575 

 .05 

 . 055 

 . 0475 

 .055 

 .045 



. 0542 



That sodium chlorid is the least toxic to wheat of all the salts 

 used is evinced by the table above. Next to it, of course, is sodium 

 sulphate. Comparing the results with those obtained by Kearney 

 and Cameron for lupines, the ^varieties of Avlieat are two and one-half 

 to three times as resistant. Coupin " also found wheat more resist- 

 ant to sodium chlorid than the white lupines. He has experimented 

 Avith several species of plants and found the whole plant to be killed 

 in the following concentrations: Wheat, 1.8 per cent: peas, 1.'2 per 



a Sur la Toxicite clu Clilorure Sodium et tie I'Eau de Mer a I'Egard Aei 

 Vegetaux. Revue Geuerale de Botanique, 10:178 (1898). 



