260 



THE AGRICULTURAL NEWS. 



August 20, 1910. 



FRUITS AND FRUIT TREES. 



THE ACID CONTENT OF LIME FRUITS. 

 .'\. report has been received, through the Curator of the 

 Dominica Pjotanio Station, of investigations that have been 

 made by ^[r. G. A. .Jones, the Assistant Curator of that 

 Station for the purpose of ascertaining the circumstances 

 upon which the acid content of lime fruits depends. 



According to this, it appeared, when the investigations 

 were commenced, that variation in acid content might be due 

 to at least si.x; different causes, acting singly, or, in different 

 degrees, together. These causes are given as: - 



(1) Variation due to individual differences in the char- 

 acters of trees growing under identical conditions. 



(2) Variation due to the variety of lime grown: that is 

 to .say, whether spiny or spineless. 



(3) Variation due to rainfall. 



(4) „ „ „ diti'erence in size of fruits 



(5) „ „ „ „ ., soil. 



iQ\ ^^ ,, ,, '-methods of cultivation and man- 



uring. 



So far, only the first four of these have been taken into 

 consideration, and that independently of one another. In 

 the experiments, equal volumes of lime juice were extracted, 

 for making the observations, from the same number of limes 

 In the following account, the different phases of the investi- 

 gation will be taken in the order given above. 



(1) In connexion with variation due to individual differ- 

 ences in the characters of trees growing under identical 

 conditions, limes were taken from the twenty-eight trees in 

 the spineless lime plot at the station, and the acid content of 

 the lime juice from each tree was determined. The tests 

 showed that there was a distinct variation in this among the 

 different trees, the lowe.st being 13-7oz. of citric acid to the 

 gallon (39-7 gr. per oz.), while the highest was 16-2 oz. to 

 the gallon (4':V2 gr. per oz.); this is is a difference of 2 5 oz 

 of citric acid to the gallon (3-5 gr. per oz.) between the 

 richest and poorest juices. It is suggested that these results 

 may form the basis of attempts to improve the lime, in the 

 matter of its acid content, by means of chemical selection. 



(2) The difference due to the variety of lime grown is 

 considered from the point of view of anal;.ses made by 

 Dr. Francis Watts, in .Antigua, and recorded in the Annual Ite- 

 ports on the Dominica Botanic Station, etc., for 1905-6 and 

 1906-7. These showed that the juice from the spineless variety 

 has a distinctly higher acid content than that from the ordinary 



one, but that this higher acidity only appeared in the case of 

 those grown at the Dominica Botanic Station: there was little 

 difference in favour of spineless limes grown in the coun- 

 try. It is pointed out that this circumstance suggests that 

 the increased acidity of the juice from the .spineless limes is 

 not a fixed character, but is affected by certain definite con- 

 ditions. 



(3) Reference is made to the common opinion that limes 

 grown in regions of higher rainfall have the weaker juice. In 

 order to gain definite information in this matter, fruit was 

 obtained from planters in different districts of the island, 

 together with information in each case as to the rainfall dur- 

 ing the preceding five months; that is to say, during the time 

 that the limes were arriving at maturity. Tests of the juice 

 give the following results; - 



These figures indicate that acidity decreases with rain- 

 fall, and they would probably have been more striking if the 

 season had not been abnormally wet. 



(4) Die variation in acid content due to the size of 

 the individual fruits is closely connected with that due to 

 rainfall, because an increa.se in the latter means the produc- 

 tion of the larger fruits. The limes for this part of the 

 investigation were received from the estate on which the rain- 

 fall was 24-4 inches for the period of five months. The smaller 

 limes yielded a juice containing 14'iS oz. of citric acid to the 

 gallon (40'6 gr. to the oz.); that from the large fruits 

 containe<l 30'7 oz. to the gallon (37'4 gr. to the oz.). 

 Although the difference is considerably in favour of the 

 smaller fruits, in considering this result in relation to the 

 yield of citric acid from an estate, allowance must be made 

 for the effect of the heavier rainfall in producing more 

 vigorous trees with a larger yield of fruits. 



A summary given at the end of the report shows: (1) 

 that lime trees grown under the same conditions exhibit 

 individual variation in the acid content of the juice: (2) the 

 higher acidity of juice from the spineless variety is not 

 a constant character; (3) the acid content ni lime juice is 

 affected intimately by the rainfall: (4) the juice from large 

 limes is weaker than that from small ones. 



