Feb. 17. i9«9 Effect of Barium and Strontium on Plant Growth 187 



of the grain showing the important constituents contained in the grain 

 produced in each experiment. 



Both barium carbonate and strontium carbonate have increased the 

 percentage of nitrogen as well as the total weight of nitrogen when 

 applied separately. Applied together, there is diminution. Barium 

 sulphate has diminished both percentage and total weight of nitrogen. 



The weights of grain and straw produced in this series of experiments 

 show increased yields in all pots receiving either barium carbonate or 

 strontium carbonate separately. The pot in which there was a mixture 

 of the two carbonates shows a decrease in the yield of grain, while the 

 yield of the straw is practically the same as that ^f the control. In the 

 pot receiving barium sulphate there is a very marked decrease in both 

 the grain and the straw, which shows the toxic effect of this compound 

 when compared with the carbonate. 



The analysis of the grain produced in each of the pots for nitrogen, 

 phosphorus, and potassium shows a sHghtly greater content of each of 

 these elements where there was an increase in the yields of the plants 

 over that contained in the control. The last two pots in the series. No. 

 7 and 8, show a marked falling off in their nitrogen, phosphorus, and potas- 

 sium content when compared with the controls and the other pots in this 

 series. The maximum increase in protein — that is, NX6.25 — ^amounts 

 to 2.60 per cent over that of the control, and the grain containing it was 

 grown in the presence of 5 gm. of strontium carbonate. The next 

 highest result was obtained where 5 gm. of barium carbonate were 

 present. The phosphorus and potassium content appears to be less 

 affected by barium and strontium compounds than does nitrogen. 



SPRING WHEAT 



In the third set of experiments spring wheat (Triticum aestivum) was 

 sown in pots containing sand to which was added the same basal plant- 

 food ration as that added to the pots in the experiments with cowpeas 

 and oats. The quantities of barium and strontium compounds added are 

 given in Table IV. In addition to the barium and strontium carbonates 

 certain pots received small amounts of what was claimed to be a very 

 active commercial radio-active fertilizer. The amount of this material 

 added to each pot is given in Table IV and is in accordance with the 

 recommendations of the company marketing this material. After the 

 young plants had reached a height of 6 or 8 inches, they were thinned 

 to the same number of plants in each pot and were brought to a state 

 approaching maturity. Unfortunately, when the wheat grains were in 

 the dough stage, a careless attendant left the ventilators of the 

 greenhouse open over Sunday and the sparrows came in and consumed 

 a part of the grain growing in each pot ; hence, the results for the grain in 

 this series of experiments were discarded. The straw was allowed to ripen 



