THE WILTING COEFFICIENT FOR PLANTS IN ALKALI SOILS. 23 



Table V. — Water contents of the soils when plants first appeared wilted, with calculated 

 wilting coefficients of the corresponding mixtures. 



Soil-mix- 

 ture No. 



Glass 

 No. 



Water content 

 when plants first 

 appeared wilted. 



For each 

 glass. 



Mean for 

 each soil 

 mixture. 



13.4 

 13.3 

 13.2 



12. S i 



13. 3 

 13.4 



15.4 

 13.7 

 13.5 

 14.6 

 13.9 

 13.8 



14.2 

 14.0 

 14.1 

 14.8 

 14.5 

 14.5 



14.7 

 14.8 

 13.8 

 14.1 

 14.9 

 15.1 



14.7 

 14.0 

 14.4 

 14.1 

 15.0 

 14.1 



14.0 

 13.2 

 14.0 

 13. 6 

 15.2 

 14.5 



13.2 



14.1 



14.3 



14.6 



Wilting 

 coefficient 

 (calcu- 

 lated 

 from the 

 moisture 

 equiva- 

 lents). 



14.4 



14.1 



13.8 



13.7 



13. S 



13.3 



13.3 



13.3 



Soil-mix- 

 ture No. 



Glass 

 No. 



10. 



11. 



12. 

 13. 



I I 



Water content 

 when plants first 

 appeared wilted. 



For each 

 glass. 



13.5 

 13.8 

 13.4 

 13.9 

 13.6 

 13.2 



13.0 

 12.8 

 13.4 

 13.4 

 13.3 

 13.5 



15.2 

 14.5 

 14.1 

 14.4 

 14.0 

 13.6 



13.6 

 14.0 

 14.1 

 13.4 

 14.1 

 14.6 



14.0 

 14.2 

 13.8 

 13.9 

 14.7 

 15.2 

 13.4 

 12.8 

 15.5 

 13.3 

 13.3 

 13.5 

 14.8 



Mean for 

 each soil 

 mixture. 



Wilting 

 coefficient 

 (calcu- 

 lated 

 from the 

 moisture 

 equiva- 

 lents). 



13.6 



13.2 



14.3 



14.0 



14.1 



13.6 

 13.8 

 13.7 



13.6 



12.9 



13.5 

 13.3 

 13.1 



The figures in Table V show the mean water content at the time 

 of apparent wilting to have been higher in most of the soil mixtures 

 than the calculated wilting coefficient. 1 Nevertheless, even in the 

 most strongly saline mixture (No. 14) in which any emergence took 

 place, the plants in at least one of the glasses were able to reduce the 

 moisture content to a percentage agreeing, within the limits of 

 experimental error, with the calculated wilting coefficient. 



On the other hand, in glasses where the plants remained very 

 small and sickly this was not possible. Thus, in one of the glasses 

 of mixture No. 13, in which the plants began to die at about the date 



i Probably because the high temperatures that prevailed toward the close of the experiment made it 

 rather difficult to distinguish between temporary and permanent wilting. More accurate determina- 

 tions of the permanent wilting point could doubtless have been made if the plants, as soon as they ap- 

 peared to be wilted, had been transferred to a saturated atmosphere in order to determine whether 

 they could recover their turgidity. 



[Cir. 109] 



