19 17. J The Fourth Indian Science Congress. clxxxix 



tion is at its best. We have from time to time investigated this point 

 and have dealt with some of the results obtained in the present paper. 



1. Linseed. 



The Indian linseed crop falls into two main classes : — 



(a) The large seeded, early, little branched types of the soils of the 



Peninsula. 



(b) The small seeded, late, much branched forms of the alluvium of 

 North Bihar and the Eastern Districts of the United Provinces. 



Associated with these differences in the above ground characters are 

 differences of equal magnitude in the root-systems. The linseeds of the 

 Peninsula are deep-rooted, the branching of the tap root taking place 

 mainly at a point about a foot below the ground level. The linseeds of 

 the alluvium are shallow rooted ; the main tap root sending out numer- 

 ous strong laterals parallel to and near the surface of the ground. It 

 would appear that soil aeration is the dominant factor in the type of lin- 

 seed grown in the two areas in which this crop is mainly concentrated. 

 On the soils of the Peninsula, the cracking of the soil enables the moist 

 subsoil to be aerated. On the alluvium, the roots are compelled to run 

 near the surface so as to secure a sufficient air-supply. 



2. Gram. 



The distribution of the gram crop in India depends chiefly on two 

 factors — soil temperature and soil aeration. Gram is an important cold 

 weather crop to the north of a line joining Bombay and Patna and is not 

 found to any great extent on the warmer soils to the southward. In the 

 gram tract itself, the density is greatest where the natural aeration of the 

 soil is above the average. 



That the distribution of this crop in the gram area depends on the 

 aeration of the soil is supported by all the results obtained at Pusa. The 

 best crops are obtained in dry years on high, well-drained soil. On stiff 

 badly aerated plots the yield falls off and the root development is shal- 

 low. In wet years, the yield is inversely proportional to the length of the 

 tap root. 



3. Wheat. 



Very little work has been done in India in tracing the connection be- 

 tween the root-systems of wheat varieties and their suitability for certain 

 types of soil. The matter, however, is being taken up at Pusa and it is 

 possible to refer to some of the preliminary results. 



Some very interesting details have been obtained on this point in 

 connection with the distribution of Pusa 12. Pusa 12 is a deep-rooting, 

 high-yielding variety. It was isolated from a mixture in the Botanical 

 Section at Pusa where it was found that this type gave excellent results 

 on the lighter wheat soils of the Experiment Station but was apt to be 

 disappointing on heavier lands. When tried in the United Provinces 

 however, it quickly came into favour. Excellent crops were obtained ; 

 the size of the ears and the yield were greater than anything that had 

 been obtained at Pusa even with the best cultivation. The soil of the 

 alluvium of the United Provinces are more open than those of Bihar, and 

 this deep-rooting wheat immediately responds. On the other hand, the 

 wheat which suits Bihar best is Pusa 6, a shallow-rooted variety which 

 does not do well in the drier wheat-growing areas of the Indo-Gangeti< 

 plain. Here the shallow-rooting is a distinct disadvantage. 



4. Hibiscus Sabdabiffa and H. cannabinus. 



These two species of fibre plants which are usually ^J^^ g 

 of the rains in Northern India, d fier greatly in two ^^J- m *J 

 amount of branching and in their tolerance of moist soil condit on, .The 

 varieties of Hibiscuf Sabdariffa are much branched P^ nte *^ 

 the «rtM mnn,nnn S and show little sign of wilt. The types of H. can 



