250 KUMPTA COTTON AND ITS IMPROVEMENT 



This study of the variation in a type of cotton, said to possess very stable 

 characteristics, leads one to the conclusion that the f-tability of Ivtnjjta cotton, 

 as ordinarily grown, has been much exaggerated. The numbers obtained, 

 furthermore, make it almost certain that the variability noticed is due not 

 to the ordinary variation in a single strain, but to tlie mixture of a number 

 of strains. Take the ginning percentage, for example, and it will at once be 

 seen that the curve obtained has fom' separate modes at 22, 24, 27 and 29 — 

 and the frequency curves representing other characters are m many cases 

 also multimodal. Such multimodal curves inevitably suggest mixture, and in 

 certain cases ^ it has been proved that they are due to the co-mmgling of several 

 different local races of a species. 



If this is the case, the first step towards improvement will obviously 

 be to determine the type or types which have the highest value to the grower, 

 ginner, and buyer of cotton, select those strains of plants which most nearly 

 conform to the various requirements, see whether these, when self-fertilized, 

 breed true, and when they do so, to multiply them and gradually replace the 

 present indefinite mixture of strains of very diflterent economic value by one 

 which combines the greatest number of desirable characters. The next chapter 

 gives the result of a study of what is lilvely to be an ideal type of cotton for 

 the humjpta tract. 



V. Ideal type of cotton for the "kumpta" tract. 



Yield. The type of cotton best suited for a tract must be greatly deter- 

 mined by the yield. The latter, therefore, must play an important part in 

 all our considerations. The part which directly yields cotton is the boll. 

 Consequently all gain in yield can only be secm"ed by improvements in the 

 boll. It is obvious that if nine bolls on each plant produce an yield of five 

 hundred pounds of seed cotton to an acre, ten bolls on each plant will certainly 

 increase the outturn by fifty pounds. Great attention must thus be paid to 

 increase the number of bolls with the object of getting better yields. 



Cotton plants vary very widely as regards their number of bolls. But 

 the variations, though intrinsic, are greatly controlled by external influences. 

 Individuals enjoying a slight advantage of plant food, moisture, or space, by 

 virtue of their position, bear a greater number of bolls than their neighbours 

 less favourably located. This, however, can be tested and the selections which 

 owe their superiority to environment only can be rejected. The matter is, 

 however, important, for, if the conditions on the testing plots are different (as 



1 De Vries. Ueber Curven — " Selection bei Chrysanthemum segetum." Ber d, devtsch., Eot 

 Ges., Vol. XVII, p. 86. 



