538 Brenchley and Jackson. — Root Development in Barley and 
disappeared, but a large number of thin roots bearing only incipient 
laterals were present until three weeks before harvest time. When the last 
plants were taken out, all the roots showed normal branching. 
Considering the manurial series together, a feature common to them 
all is the steady rise in the numbers of the white unbranched roots for the 
period extending from the 7th to the nth week after sowing and their 
disappearance after that time. 
Relative growth of root and shoot in Barley. The relative growth of 
the root and shoot, as measured by the amount of dry matter produced, 
shows an interesting correlation with the morphological development of the 
root at different periods of growth (Table II and Fig. 1). 
For the first six or seven weeks growth was very slow, and the plant 
seemed to be laying the foundations for future development. The actual 
difference between the dry weight of. root and shoot after seven weeks was 
not very great, but by this time the beneficial effect of the superphosphate 
which was added at the beginning was already marked. During the next 
fortnight a rapid increase in growth took place, and a still further increase 
occurred afterwards, the latter being more marked in the shoot. In some 
cases the shoots continued to increase in dry weight till harvest time, though 
in others a slight fall was indicated towards the end. The roots, on the 
contrary, reached their maximum weight long before the harvest, the exact 
period varying with the manures applied. The unmanured roots, as would 
be expected, made less growth than any others : they increased in dry 
matter for about seventeen weeks and then gradually lost weight till 
harvest, seven weeks later. The biggest root growth was given by sodium 
nitrate, much the same result being obtained whether superphosphate was 
present or not. The general effect of manuring was to hasten the rise to 
a maximum, which was reached in most cases after fourteen weeks’ growth, 
though in unmanured soil and in the presence of superphosphate and 
sodium nitrate together increase continued for seventeen weeks. From the 
maximum a fairly rapid and steady decrease in dry matter took place until 
at harvest time most of the roots, with all types of manuring, were of much 
the same weight and were reduced to what they had been after only ten or 
eleven weeks of growth. 
This decrease in weight appears to be associated with an actual loss 
of root materia] due to decay or to migration into the aerial parts. At the 
time the roots were at their maximum they were strong and well developed, 
but afterwards at each successive washing out it was obvious that deprecia- 
tion was taking place, till by harvest time the roots were very poor and 
feeble. 1 
1 The superphosphate and sodium nitrate root seemed to be an exception to this, as the< last 
plant observed had a very massive and heavy root. Unfortunately only one plant was available at 
this date, but it is quite possible that this may have been an exceptional one, as those observed three 
