SALT REQUIREMENT FOR BUCKWHEAT PLANTS I9I 
portions producing maximum yields of tops in water cultures are in 
perfect agreement with those giving the highest dry weights of tops 
in the corresponding series of sand cultures, during each of the two 
different growth periods. This is further emphasized by a similar 
agreement between the salt proportions producing maximum yields 
of roots in the series of water cultures and in the corresponding series 
of sand cultures, during the late growth period, from flowering to 
maturity, although there is no such agreement between the salt pro- 
portions producing the maximum yield of roots in water culture and 
those giving the highest dry weight of roots in sand culture, during 
the early growth period. The salt proportions which produced the 
highest yield of seeds in water culture are not like those which gave 
the highest dry weight in sand culture. In this connection it should 
be mentioned, however, that the water cultures were conducted at a 
season of the year when insects were absent, and pollination by artifi- 
cial means was perhaps imperfectly accomplished. The plants of the 
sand cultures, on the other hand, were in bloom at a time when insects 
were abundant, and these had free access to the plants. It will be 
observed that in this series the salt proportions giving the best growth 
of tops and of roots are the same as those which produced the highest 
yield of seeds. 
It is interesting to observe that with three out of the four average 
series here represented, there is a definite correlation between the 
growth of tops and that of roots, as is clearly indicated by the perfect 
agreement between the salt proportions producing the highest dry 
weight of tops and those giving the maximum yields of roots. 
As the relative dry weight values in the last two columns of the 
above table indicate, the three-salt mixture with a total osmotic con- 
centration value of 1.75 atmospheres, and with proper salt proportions, 
produced markedly higher yields than did either Knop's or Totting- 
ham's solution with the same total osmotic concentration, for the two 
different physiological growth periods here considered. 
The New Jersey Agricultural Experiment Station, 
New Brunswick, New Jersey 
