1&6 STUDIES IN THE POLLINATION ON INDIAN CROPS 



1915.1 Some of the information relating to Java indigo was published in 



1916.2 The present paper deals with the results obtained, up to the end of 

 the rabi harvest of 1919, on the following crops : — San-hemp {Crotalaria 

 juncea L.), pigeon pea {Cajanus indicus L.), Java indigo {Indigojera arrecta 

 Hochst.), Sumatrana indigo {Indigojera Sumatrana Gaertn.), linseed {Linum 

 usitatissimum L.), taramira {Eruca saliva Lam.), til (Sesamum indicum L.), 

 niger {Guizotia abyssinica Cass.), jute {Cor chorus capsular is L., and C. 

 olitorius Ij.) and ToseWe . {Hibiscus Sabdarijfa L.). 



The bearing of pollination studies on such subjects as the methods of 

 improvement of crops, the introduction of exotics, the maintenance of types 

 and the distribution of pure seed to cultivators, has already been discussed 

 in two papers^ (published in 1910 and 1912) largely from the point of view of 

 the application or otherwise of the methods of pure line selection. Some of 

 the results described in the present paper, for example, those dealing with the 

 pigeon pea, indigo, and san-hemp, bring out other aspects of plant 

 improvement which are not without interest at the present time. 



In the pigeon pea, a crop widely grown and of great value in the rural 

 economy cf the country, yield is of far greater importance than quality. The 

 problem before the breeder is to secure the heaviest crop possible. In carrying 

 this out, the facts dealing with pollination and fertilization show that other 

 factors, besides potential yielding power, are involved. Fertilization depends 

 on atmospheric conditions and practically no setting takes place during damp, 

 dull weather although self-pollinated flowers may be produced in profusion. 

 This adverse factor can be avoided by increasing the range of the flowering 

 period. This can be achieved most easily by the growth of a mixture of indi- 

 viduals differing considerably in time of flowering. In this way the risk is 

 distributed and the yield is insured. This, however, involves the rejection 

 of the method of pure line selection and the adoption in its place of mass selec- 

 tion in which crossing within certain limits is permitted. 



In Java indigo the case is still more interesting. The crop consists of a 

 mass of freely crossing heterozygotes with a wide range in general habit, root 

 development, time of flowering and in the extent of leaf surface. Practically 

 no setting takes place if insect visitors are exchided. The seed produced by 

 artificial self-pollination is small in amount and gives rise to progeny of less 



^ Mem, of the Dept. of Agr. in India {Botanical Series), vol. VII, nos. 6 & 7, 1915, pp. 213 

 & 237. 



2 Bulletin No. 67, Agr. Research Inst. Pusa, 1916, p. 23. 



3 Mem. Dept. of Agr. in India {Botanical Series), vol. Ill, no. 6, 1910, and Agr. Jour, of 

 India, vol. VII, 1912, p. 167. 



