Vol XI. No. 268. 



THE AGRICULTURAL NEWS. 



245 



AGRICULTURAL, EXPERIMENTS IN 



GUADELOUPE. 



The Director of the Experiinenttil Garden at Pointe-a- 

 Pitre has issued recently a report on the work done in the 

 Garden during the pa.st year. This is reviewed in an article 

 in the .faurnal d'Af/rii-idture Tropica/e for March 1912, from 

 which the following information ha.s lieen taken. 



'i'rials have lieen made with several kind.s of coffee, 

 inclu'litig Cofea stenoj'liylla, C Canephora, C. iUierica, and 

 Abyssinian coffee. Anrng these, the Liberian cotfee 

 appears alone to be suitable for cultivation; the others have 

 shown themselve.s inferior to the universally appreciated 

 indigenous ctiffee, called l^etit Cafe. The cultivation of 

 cacao has been e.xtended as far as possible, but no new varie- 

 ties hai-e been tried; these which have been distributed in 

 the past are to be found in the island, l)ut are only taken up 

 On a small scale. 



The cultivation of the lime a[ppears to have received 

 a great impulse; numerous plants and feeds have been dis- 

 tributed, and it is likely that its culture will be remunerative, 

 as a hectare is capable of producing, at the end of five years, 

 a gross return of 1,000 francs per annum (ne-jrly £16 per 

 acre), and it is held that the crop douliles itself toward the 

 seventh or eighth year. The lime plant, almost wild in 

 Ciuadeloupe, grows well and yields an abundance of fruit. 



K.xperiments have l>een conducted with rubber plants of 

 various kinds, and it appears that I'icus will prove to be 

 most suitable for the island: it grows vigorously in all the 

 soils, and is resistant to drought. Castilloa possesses 

 a ripid growth: a plant two years old, at the Experimental 

 Garden, is already 13 feet high and in inches at the base. 

 The same succe.ss has not been obtained with MamhiA 

 Gla-.l'tvii; the brittleness of the wood causes it to show 

 little or no resistance to wind, several specimens have 

 died after being tapped; the clay soils of the island are not 

 well suited to it. The several I'uDtuniia plants that have 

 received attention have possessed a slow development, which 

 give.s little encouragement, at the commencement. Hevea 

 has also been tried, but the insignificant germination of 

 the seeds, which as is known easily perish, has not per- 

 mitted a sufficient trial to be made with this species. 



Lastly, Euphorbia Intiiy, tried mostly as a curiosity, 

 has grown easily and well. None of these plants have been 

 tapped methodically — some of them not at all — and it is not 

 I)Ossible to form any opinion as to which of them is most 

 suited for rubber culture in Guadeloupe. 



Attempts at afforestation with valuable species of trees 

 hive been carried out with mahogany (Sirietetiia Afahai/oni.), 

 Guaiacum (Guaiacwin officinale) and courbaril, the West 

 Indian locust or algaroba {Hymsnaea i'oiirbaril), the rapid 

 destruction of which necessitates planting on a large scale. 

 Trees of mahogany sixteun years old exist already, which are 

 large enough to be cut; this is a matter for encouragement. 

 Venezuelan kapok has developed rapidly, and there is much 

 hope of its success; it has not met with a very enthusiastic 

 reception from planters, probably because they are unaware 

 of the value of the product in the Sluropean market. With 

 regard to textiles, properly described, mention may be made 

 of trials with Furcra»»a and with Stnsei'ieria zeylanica. 

 Regret is expressed in the article reviewing the report that 

 these two kinds have been chosen in preference to sisal hemp, 

 a.s Furcraea yields a less valued article, md as the market 

 for Sansevieria is still insutficiently established. It may be 

 said, nevertheless, that F'urcraea does not seem to be likely 

 to suffer great harm from di.sease, for it already grows verv 

 'mjll in all parts of the island. 



In concluding the review, it is stated that the Experi- 

 mettal Garden at Guadeloupe has given during the year 

 proofs of the existence of an activity which will enable it to 

 obtain results of the greatest interest for the French Antilles, 

 and satisfaction is expressed th-it an attempt is b,ring made 

 to follow the advance that has already been .shown by the 

 English islands of the Antilles, 



ABSORPTION AND EXCRETION BY 



PLANT ROOTS IN CULTURE 



SOLUTIONS. 



Unpublished work that was carried out by the United 

 States Department of Agriculture several j'ears ago for the 

 purpose of investigating the changes that take place in 

 cultu'c solutions in which seedlings of the white lupine 

 {Lupiniis aU'us) are grown, by ascertaining the change in the 

 ability of the solutions to conduct water (their conductivity), 

 has suggested work in the same direction that is described in 

 Jjalletin So i.'Sl of the Bureau of Plant Industry of that 

 department, issued at the beginning of this 3 ear. 



The results of the old work, which are mentioned in the 

 bulletin ipioted, indicated that lupine roots, when grown in 

 distilled water, excrete electrrilytes which make the water 

 so used better able to serve as a medium for growing 

 a second set of seedlings. It may be mentioned that electro- 

 lytes are salts which dissolve in water to form so'utions in 

 which the constituents can be broken up in a definite way 

 by passing an electric current. In such solutions the con- 

 ductivity is proportional to the amount of electrolytes pre- 

 sent, so that it was suggested for the new work described in 

 the HuUetin that this method of ascertaining the amount of 

 eleetrolyte.s present should be employed. 



In the investigations, Canadian field peas were grown 

 in extremely dilute solutions of calcium and magnesium 

 nitrates. A summary that is given, of the conclusions 

 reached as a result of the experiments, shows that among the 

 first of the.--e was the fact of the existence of a concentration 

 for each salt or mixture of salts at which the latter 

 are absorbed and excreted by the roots of peas at the 

 same rate Further, if the solution has a concentration 

 less than this amount, more of the salts is excreted from the 

 roots than is absorbed; on the other hand, with a more con- 

 centrated solution, there is more absorption than excretion. 



The definite concentration at which absorption and excre- 

 tion proceed at the same rate is referred to shortly as equili- 

 brium concentration, and a further result shows that the 

 action of the roots on solutions stronger than equilibrium 

 concentration may be to make them rauch weaker than this 

 concentration. Proceeding, the interesting result was reached 

 that the extent to which the concentration may be brought 

 by the roots beneath equilibrium concentration depends upon 

 the ratio of the magnesium to the calcium in the solution. 

 From a quantitative point of view, it was found that the 

 greatest absorption took place when the weights of calcium, 

 and magnesium present were in proportion to their molecular 

 weights. 



Turning now to the effect of the solutions on the growth 

 of the pea roots, the experiments show that their develop- 

 ment was good when the ratio of magnesium to calcium was 

 9 to 1; thit is to say, under conditions in which the con- 

 centration of the so'utions was so great that if magnesium 

 salts had been present alone the growth of lateral roots would 

 have been i)revented. If, however, the solutions are so dilute 

 that the amount of magnesium in them alone would not pre- 

 vent such growth, the ratio just mentioned, is nearer 99 to 1, 



