Wheat tender Different Conditions of Growth. 547 
no roots here comparable to those found in the superphosphate plants, 
where the ends had become rotten. This may be due to the better tilth 
obtained in a soil treated with farm-yard manure. Several of the roots 
penetrated to a depth of 9 in., and again it was observed that the roots 
coming off from the node were rather thicker and less branched than those 
coming from the grain. 
Root System of Wheat. 
Pot Cultures. 
In wheat, as in barley, a strong root system developed, the types 
being more or less similar except with regard to the behaviour of the white 
roots. Nine days after sowing, when the shoots were about \ in. long, the 
roots of both the unmanured and the superphosphate plants were very 
similar. A typical plant possessed 3 roots up to 4 in. long, with 
abundant root-hairs. Five weeks after sowing the unmanured plants were 
found with 4, and the superphosphate with 5 roots, the longest of which 
in both cases reached 21 in. These numbers are rather lower than those 
obtained in the barley plants, where 7 or 8 roots were developed in 
seedlings 5 weeks old, but the maximum length of root was the same for 
both wheat and barley. Lateral development was consistently stronger in 
all the manured plants than in the unmanured, and in all series the laterals 
showed a tendency to concentration in the upper 14-16 in. of the roots — 
a tendency which was also very noticeable in all the barley series. The 
nitrate plants here did not show the crinoline effect which was so noticeable 
in the barley manured with nitrate, but the roots of the wheat receiving 
potash were very similar to the corresponding barley roots, for near the 
crown the roots of the potash plants were very woody and stood out exactly 
as described for barley, though to a less marked degree. 
In the early stages of growth, seven weeks after sowing, there was 
a distinct tendency towards thickening at the ends of the long branched 
roots, and this tendency became more marked as growth proceeded. When 
the roots had attained a considerable length, it was found that they coiled 
up at the bottom of the pots, and the coiled up parts were always much 
thicker than the rest of the root, and also bore few or no laterals. 
No ‘ white 5 roots appeared until seven weeks after sowing, when a few 
were found in the more heavily manured plants. Later, they were present 
in all the manurial series, but in no case did they retain for very long their 
unbranched character, the result being that long, branched, ‘ white 5 roots 
were found fairly frequently. 
