INSTITUTE, PUSA, FOR 1917-18 43 



in Africa, and that the money value of a single successful 

 introduction like Pusa 12 is out of all proportion to the cost 

 of a Research Institute. 



2. Indigo. 



The investigations on this crop, referred to in previous 

 reports, have been continued during the year and have 

 been confined largely to Java indigo. As this crop, when 

 grown for leaf, is in the ground for nearly a year, it must 

 be remembered that it differs entirely from the ordinary 

 cold weather and monsoon crops as it has to maintain itself 

 under a very wide range as regards soil conditions. Sown in 

 September or early October, the first portion of the growth 

 period takes place under cold weather conditions. The 

 crop then has to survive the hot season when dry west 

 winds are to be expected after which the temperature of 

 the surface soil rapidly rises. The plant then completes 

 its first year's growth in the monsoon phase, during the 

 latter portion of which the aeration of the soil is interfered 

 with by the cessation of drainage due either to the rise of 

 the rivers, the flooding of the country, the rise in the sub- 

 soil water level or to a combination of these causes. In 

 interpreting the results obtained with this crop, therefore, 

 it will always be necessary to bear in mind these facts. It 

 is generally in the second half of the monsoon and after 

 the first cut has been taken that growth slows down and the 

 plant often becomes diseased. 



Much time has been spent in the investigation of the 

 root system of this cropland the effect thereon of any altera- 

 tion in the soil conditions and also of cutting back to 

 varying degrees. The roots of Java indigo are exceedingly 

 sensitive to undecayed organic matter such as oil cake, 

 fresh san hemp (Crotalaria juncea) weeds or partially 

 decayed indigo, particularly when these substances are 

 added to the soil at times when the aeration is poor. It is 

 then possible to kill the crop outright by these means. 

 When, however, the damage does not proceed so far, the 



root system is often profoundly affected, the total absorbing 



d2 



