28 SOME ASPECTS OF THE INDIGO INDUSTRY IN BIHAR 
by continuous selection or a repetition of the wilt problem is inevitable. To 
achieve this object, the seed must be grown in Bihar and the annual selection 
necessary must. be carried out locally. Thus the raising of seed is a matter 
of the very greatest importance to the future of the indigo industry. 
The factors underlying seed production. 
The solution of the problem of seed production was found to lie in the 
growing of a special seed crop and in obtaining the seed from the most vigorous 
plants. This was accomplished by sowing the seed crop in early August 
by which time the rains were half over. Provided high lying land in good 
condition with excellent surface drainage is selected and attention is given to 
surface cultivation, the seed crop can be established even in the wettest years. 
At first, growth is slow and root-development is largely confined to the upper 
layers of soil. As the level of the ground water falls, the soil aeration umpreves 
and the roots invade the deeper layers. By October the crop is established 
and growth then becomes rapid. The yield of seed has been found to depend 
on two factors—fertilization and the rapid growth of the plant. 
Fertilization. The conditions necessary for fertilization were found 
to be temperature and humidity. In Bihar, indigo can be made to flower 
at almost any period of the year but it only sets seed if the temperature 
and humidity are both favourable. In September and early October, the air 
is too damp:for setting to take place and although flowers and pods torm, 
practically no seed is obtained. 1n December, it is too cold tor fertilization. 
The best period in the year is the six weeks between October 15th and 
November 30th, when the weather is warm and dry. At this time, fogs 
and rain are practically unknown. Bees are very active during this period 
when, other things bemg favourable, practically every indigo flower is 
visited and yields good seed. For all the flowers to be worked over, the 
plants must be properly spaced and allowed to branch freely. Anything in 
the nature of overcrowding prevents proper branching and also keeps the air 
round the plants toodamp. It is best, therefore, to grow the crop in lines, 
about three feet apart, and to attend to spacing in the rows from the very 
beginning. ‘he plants should be well forward by the middle of October, so 
that flowering begins about this time. Any great delay means a reduced 
yield of seed. 
Rapid growth. It is obvious that the production of a heavy crop of 
seed necessitates a large and vigorous plant. This is only possible if the soil 
conditions are maintained at the optimum. ‘The fields selected must be high 
lying, above the flood level and the surface drainage must be good. The 
