290 



THE AGRICULTURAL NEWS 



September 21, 1918. 



"tropic? will do this, an.J the problem of getting good 

 varieties for cultivation under the long-ratooning sys- 

 tem necessitated here by our deficient labour-supply 

 and dependence on hand, instead of on mechanical, culti- 

 vation, becomes an exceedingly difficult one. Elsewhere, 

 with the excej/tion of Cuba, sugar-canes are as a rule 

 only cultivated as plants, or as plants and 1st ratoons. 

 Hence as the best varieties raised in Barbados, Java, and 

 Hawaii have been chosen for their suitability for short 

 ratooning periods, it is rarely that a sugar-cane suitable 

 for our long-ratooning conditions can be imported from 



•elsewhere. 



The most successful method we have tried here 

 for raising new varieties of sugar-cane of promise is 

 based ©n the facts that a sugar-cane for successful 

 cultivation on oar heavy clay soils must be of well- 

 marked vegetative vigour, and that whilst the range 

 of variation in the saccharine content of seedling 

 sugar-canes is very great, its relative sugar-content 

 is a fairly fixed characteristic of any variety. We 

 •endeavour to raise as many seedlings as we can from 

 varieties of proved vegetative vigour, and select from 

 them those having both well-marked vegetative vigour 

 and relatively high saccharine content. By this method 

 we raised from D.62.5 the seedlings D.118 and D.419, 

 the areas under which have increased from 2 acres, and 

 1 acre, respectively, for the crop of 1911-12, to 2,710, 

 and 1,360 acres, respectively, for this year's reaping. 



•We have been advised time after time to give up 

 our proven methods and to confine our efforts towards 

 raising canes by cross-fertilization. If we had in this 



•colony sugar-canes of single parentage showing fi.xed 

 characters and, through their purity of origin, having 

 little or no tendency to mutation or sporting, that advice 

 would be excellent. In India, and to a less extent in 



- Javn, sugar-cane varieties of high purity of strain exist; 

 and with these it is possible that by the application of 

 Mendelian principles in raising seedlings, new varieties 

 of high value may be obtained. Up to the pre.sent, 

 however, this has not taken place. 



'At the inception of the sugar-cane breeding work 

 here, .Jenman was enthusiastic over the possibilities ot 

 raising new varieties of high promise by controlled 

 methixJs of cross-fertilization: but in l.S!l2-;i our hopes 

 in that direction received a severe shock. Using a vari- 

 ety of sugarcane, the Kiira-kara-wa cane, which our 

 experience in three preceding years had shown to 

 produce si'edling-canes having usually soiiiewhat close 

 reseniblance to the parent variety, and placing it under 

 conditions by which it was impo.ssible for its arrow or 



Howering shoot to be either cross-fertilized by any other 

 variety, or fertilized by any other flower shoot of its 

 own kind, we got seedling canes from the one arrow of 

 2y7 difi'erent sorts. The parent cane in its own seedl- 

 ing stage was hence possibly derived from fourteen 

 diverse ancestral strains. 



'Supposing, for example, that we take two kinds of 

 sugar-cane, one, X, having as ancestral kinds the varie- 

 ties A, B. C, D, E and F, and the other, Y, derived from its 

 ancestors A,B,G,H,I, and J, it is evident that 406 diflPer- 

 rent combinations can arise from the interbreeding of 

 the two kinds, instead of a single blend or cross, X x Y. 



'By Mendelian segregation, the inheritable proper- 

 ties of this diverse progeny will fall into three groups. 

 We do not know which properties are inherited; but 

 assuming that the general characteristics as a whole are 

 heritable, the segregation of the seedlings from the 

 cross X and Y may give rise in the first generation to 

 1,218 groups of varieties. 



'Now either Xor Y, by interbreeding with its own 

 kind, could produce only 15x3 groups or forty-five 

 general strains of sugar-canes. The complexity intro- 

 duced by the cross-fertilization of existent complex 

 hybrids is well illustrated by this example. 



'Up to 1902 we had not made any systematic 

 attempt at raising canes of controlled parentage. We 

 now do it as a matter of regular routine — not with any 

 iilea of getting seedlings having definite and desired 

 characteristics, but as a means of greatly widening the 

 range of their variation. We have complete proof of 

 the success of the method in this line. Unfortunately, 

 there is no chance in British Guiana of controlled cross- 

 fertilization of the sugar-cane proving a short and cer- 

 tain way to success in the productioi! of new varieties 

 of high saccharine value. 



'Probably a more disappointing investigation has 

 never been pursued than has been the search for 

 improved varieties of sugar-cane. There are now many 

 stations at work at it in the tropics and sub- tropics; 

 their results appear to be very similar: in the earlier 

 years working w^th natural varieties of sugar-cane, 

 several kinds of high promise are almost invariably 

 obtained: in later years, when the mass of material for 

 parental purposes has rapidly and enormously increased, 

 the production of really good varieties appears to 

 become increasingly difficult, and results satisfactory 

 to both investigator and planter tend to be few and 

 far between. It looks as though the good results arose 



