196 



THE AGRICULTURAL NEWS. 



June 29, 1918. 



SUGAR INDUSTRY. 



STUDIES IN INHERITANCE IN 

 SUGAR-CANE. 



Mr. H. B. Cowgill, I'laiit lireetler, Insular Experiment 

 Station, Porto Rico, contributed to the Journal of Ihc 

 Depailmoit of Ai^ricuitui'. oj Porto Rico, January 1918, 

 a pxper on the above subject, in which he records such data 

 ;is have been sJccured from inve.stigalions of seedlings which 

 were being propagated and selected art that station, although 

 only a few experiments had been conducfed for the sole 

 purpose of studying .juestions of inherilance in the : ugar- 

 cane. 



Points of interest are: ( 1 ) the extent to wliich ciiaracteis 

 are inherited from the parent varieties when the latter are 

 selfpollinited: (2) whether new types are produced in the 

 nature of mutations; (3) to what manner and to what degree 

 varieties when crossed cin be expected to transmit their 

 characters to seedlings. 



It seems from Mr. Cowgill's observations that, in general, 

 even when cros.s-pollination has not been attempted, there 

 is a difference in the appearance and probable value of 

 seedlings produced from the different vaiieties, and that 

 . there is als-o considerable ditl'erence in tlie amount of resem- 

 blance of the seedlings to the parent variety. The reason 

 for this may be that all cane varieties are probably more or 

 less heterozj'gous. It is also possible that accidental inter- 

 cro-ssing sometimes takes place between varieties growing in 

 the same locality, and that this affects the appearance of the 

 resulting seedlings. 



The seedlings under 'ibservation in the Porto Piico 

 experiment station were raised from seed obtained from 

 unprotected cane arrows. For that rea.son the purity of the 

 pollen cannot be guaranteed. However, it is not probable that 

 .sugar-cane pollen is carried more than a short distance by 

 the wind, as it has no special adaptation for being thus 

 transported, and is soft and delicate. It is probable, therefore, 

 that the stigmata of the Howers of the cane in the centre of 

 a field planted in one variety, are entiiely fertilized by pollen 

 of the same variety. 



The following observations on seedlings produced from 

 five uncrossed varieties are of interest. 



The seedlings produced from seed of J). 109 showed 

 a very close resemblance in outward characteristics to the 

 parent cane every year since 1913. IJ. 109 is a dark greenish- 

 red to purple cane, usually reclining in habit, with buds 

 semi elli|)tical in shape. Many of the seedlings plainly show 

 some or all of these characteristics, while the resemblance as 

 to colour is especially noticeable. 



The majority of the seedlings from seed of T.77 

 resemble the parent very imich in colour and habit, and more 

 or less as to the form of the bud. 



Of the thirty-four .seedlings produced in 191'! from the 

 light-coloured cane, H. 347, only two are of a darker shade 

 than the parent. 



The seedlings of B. 109 were all like the parent variety 

 in colour, and more or leas resembled it in the shape of the 

 internodes and the buds. A few of them however were 

 slightly tinged with red on the upi)er internodes. There 

 were however other variations among these seedlings: two 

 were markedly jjlaucous, one had sjiecially prominent buds, 

 one had extremely small juints, two had many adventitious 

 roots , one had cHpecially ihin stalk", one was very thick- 

 stalked. There was also a great difference amongst these 

 seedlings as to vigour of growth. 



Out of 366 seedlings from D. 148, which is a red cane, 

 GO ptr cent, showed redness on the stalk, though .some in 

 a less degree than in the parent variety. Among the 

 remainder there were two wine-coloured canes, two 

 greenish yellow, two reddLsh green and glaucous, three were 

 light reddi.sh green and glaucous, and one had distinctly 

 tumid joints. 



All seedlings produced from 1). 117 seed showed marked 

 lesemblance to the parent in colour and habit of growth, but 

 they have shown much vari ition in the type of the internodes 

 and the bud. .Vbnornialities rendering a cane unfit for 

 commercial cultivation, such as dwarf cane.s, extremely short 

 internodes and wejge-.shaped internodes have been common 

 in these seedlings. Of the 900 seedlings of this variety 

 grown to maturity in 1916-17, only one differed in colour 

 from the parent variety, beinj green instead of yellowish 

 green. Twenty four of them wore classed as abnormalities, 

 nine of which were dwarfs. Tbey had stalks not over 3 feet 

 long, internodes A to 1 inch long, usually semi prominent buds, 

 and erect growing leaves. Other unusual characters in these 

 abnormal canes were stalks with all or miny of the buds 

 sprouted, and stalks with many adventitious roots. Some 

 (ilants also had stalks with wedt;e-shapcd internodes. 

 averaging .about 1 inch long on one sHe of the stalk, and 

 narrowed down to sometimes practically nothing on the 

 opposite side. It is planned to grow Eo.ne of these varia- 

 tions to see whether the abnormal chiracters are inherited. 



It may be that such unu.sual types are due to characters 

 acquired by intercrossing of virions types of cine at an early 

 stage in the development of the species, and that these charac- 

 ters have been hidden by reason of the do^iiinance of others, 

 since the sugar cane has been propagated asexually for an 

 unknown period of time. Hat the iiut-stion also arises whether 

 such abnormalities are not of the character of mutations, 

 and whether some of the other variations in cane seedlings 

 may not .vlso belong to the same clas.s. 



The following interesting observations were made by 

 Mr. Cowgill with regard to seedlings produced by pollinating 

 the flowers of the Crystallina cane with pollen of D. 109. 

 These seedlings show resemblances to both parents; some 

 of them were almost identical in appearance with the 

 pollinating variety, while a few closely resembled (.Vystal- 

 lina. P.etwcen the two types many variations were 

 found. Whcrj the parents are not so distinctly differ- 

 ent in colour as these two varieties, it may not be 

 absolutely certain whether individual seedlings are from 

 cross-pollination or from self pollination of the variety 

 intended for the .seed piient. On a whole, however, the 

 progeny can be considered cress-pollinated stedlings. 



Of the canes resulting from this cross pollination last 

 year, many appear promising for conunerciil culture. Only 

 one abnormal stool was found among iheni. The data 

 obtained from the comparison of the characteristics of these 

 cro.ss bre<f seedlings indicate thit there is a form of combina- 

 tion of charaolers in some at least of them, resulting from 

 the cross. There is a greater variation also in seedlings 

 so produced than in those obtained from flowers not cross- 

 pollinated. 



DEPARTMENT NEWS. 



Of. C. 1'. .Stuule, .M.D. \ ., Oo\eiiiiiieiit Veterinary 

 Siirt^eoii, St. Vincent, has resigned that otHce, on hia 

 .appointiHi-nt by the local < io\ eminent as Inspector 

 of Impoiterl .\ninials injlSarbados. 



