34 SOME ASPECTS OF THE INDIGO INDUSTRY IN BIHAR 
nitrogen through denitrification. In September 1917, a somewhat stiff piece 
of land was waterlogged for a month and sown with Java indigo the following 
October. The effect of the waterlogging on this leguminous plant was very 
marked. Five months after sowing, equal areas on the waterlogged and 
control plots were taken and the heights of the plants were measured. On the 
waterlogged plot, the average height of 200 plants was 10°5 em. ; on the con- 
trol, the average height of an equal number of plants was 28°0 em. When the 
root system of the plants on these plots was examined, it was found that the 
first effect of waterlogging was to restrict the roots to the upper layers during 
the first few months of growth and to change the general character of the root 
system. The results are shown in Fig. 1. On the left is represented the root 
4 
Fic. ] The root system of Java indigo showing the effect of waterlogging before sowing 
(left) compared with the control (right). 
system of a plant from the plot waterlogged a month before sowing, on the 
right a specimen of the roots from the control plot is to be seen. In the water- 
logged plot, the development of the tap-root is arrested and one of the laterals 
after bending takes its place. In the case illustrated, the acting tap-root was 
followed to some distance and was found to give off very few branches. 
