57 
The Effect of Weeds upon Cereal Crops. 
decrease on the figures when grown alone. The dry weight also 
dropped considerably. It is interesting to note that the detailed 
analysis of weight, number of spikes and root development reveals 
a far greater depreciation in the growth of Alopecurus with wheat 
than was evident during the growing period. Although some 
depression was evident, it looked comparatively slight, and the 
analytical figures, revealing a depression of some 40% in the presence 
of wheat came in the nature of a surprise. 
The wheat was as deceptive as the Alopecurus. It appeared 
to be very poor and backward (except in one pot) and to be most 
adversely affected by the weed. As a matter of fact the height of 
the plants was rather low, 26—39 cms. (reaching to 62 cms., in the 
good pot) and this probably gave rise to the impression of poor 
development. The roots were quite well-developed and fibrous. 
Altogether 30 ears were formed, of which 21 were fully developed, 
as against 45 and 23 from twice as many plants grown alone. In 
proportion the dry weights of these wheat plants were far heavier 
than in the absence of the Alopecurus , though the totals did not 
approximate quite so closely as with wheat and Papaver. 
SOIL B. TOTAL DRY WEIGHTS OF CROP IN SIX POTS. 
Shoot. 
Root. 
Crop. 
Weed. 
Wheat + 
Weed. 
Grams. 
Grams. 
Grams. 
Brassica + Brassica 
51-4 
70 
366 
Wheat-f Brassica 
25-3 
10-6 
70-7 
Wheat + Wheat 
27-4 
57-9 
Wheat + Spergula 
1-9 
21-4 
Spergula + Spergula 
39-6 
1-9 
AVERAGE DRY WEIGHTS OF SHOOTS. 
Crop. 
Weed. 
Per plant. 
Per single sowing. 
Per single sowing. 
Grams. 
1-525 
1- 473 
2- 413 
Grams. 
6-1 Wheat- 
5-89 Wheat + Wheat 
9-65 Wheat- 
Grams. 
Brassica + Brassica 4-27 
L Brassica 4-22 
b Spergula 0-32 
Spergula + Spergula 3‘3 
