Vol. XV. No. 31 



THE AGRICULTURAL NEWS. 



2.51 



rougli lemon (Citrus liiiionuin), and the lime are practically 

 unknown as stock.? in California ; but it is stated in the 

 Bulletin referred to, that a more extended trial and careful 

 study of these lesser used stocks are greatly needed. Tables 

 are given showing the average yields of fruit, and the average 

 volumes of the trees. This latter measurement is taken as 

 an index of the tree's vigour, and might be similarly em- 

 ployed in the ca.se of manurial and other experiments in the 

 West Indies with limes and Cicao. A formula is given for 

 finding the volume of each tree: — 



Volume in cubic feet = -'^ ("- l(i5H_Z_'*)\ 



4p I 2 12p / 



Where 



c = circumference of tree, 

 o = distance over top of tree, 

 p = ;3U16. 



With regard to a discussion of the results, a consideration 

 of the table of comparative yields makes it clear that these 

 data are purely indicative, and in no sense proper as a basis 

 for definite conclusions. The yields indicated are in all cases 

 extremely small, even for average values. This is of course 

 primarily due to the fact that the figures are those of the first 

 years' of production in the life of the trees; the very low yield 

 of the first year or two has naturally reduced the average for 

 the five years to a considerable degree. Allowance must al.so 

 be made for the severe cold waves of December 1911 and 

 January I'JIS. which may have had their effects upon the 

 succeeding bloom and crops. This is undoubtedly true in the 

 case of the lemon yields. 



'It is evident, however, that there is no ground at present 

 for recommending any particular stock for increased yield 

 or quality of fruit of either of the oranges or the lemon used 

 in these experiments. Such evidence could scarcely be 

 expected at the end of the first half decade of an experiment 

 the nature of which demands an accumulation of many years' 

 data as a pre-requisite for sound conclusions. As.suming 

 a future increased annual production consistent with the 

 increasing age of the tiees, we may properly look for more 

 differences between the yields of trees on different stocks in 

 the averages of the next five or ten years, if such differences 

 are to become evident under the conditions of the experiment. 

 Moreover, any factor making for reduction in yield or quality 

 of fruit or in size of tree which may be as.sociated with early 

 growth — a characteristic accredited to sour stock for example 

 — should disappear in the future records. 



'Conclusions regarding the superiority of any one stock 

 for its effect upon growth are likewise wholly unwarranted at 

 pre.sent. Attention is called to the fact that the behaviour 

 of the orange, both navel and Valencia, has varied on the 

 two plots in regard to the size of trees on trifoliate and the 

 other stocks, and that in no case has the use of the former 

 effected a marked or undesirable dwarfing. Valencia has been 

 particularly thrifty on the trifoliate root. Indeed the most 

 striking fact of the experiment evident to date is that Citrus 

 trifoliata, per se, does not necessarily dwarf all species or 

 varieties budded upon it. Where such dwarfing occurs, it 

 is highly probable that conditions of environment are largely 

 re.sponsible. Further and more extensive investigation of 

 these stocks on a number of widely different .soil types is 

 essential for a final answer to this question. 



'On the other hand, the dwarfing of Eureka lemon on 

 trifoliate root has been so extreme and so consistent that we 

 may justifiably regard it as highly undesirable for that fruit. 



'A point of interest in connexion with the use of 

 Citrus trifoliata as a stock is the characterstic increase 

 of the diameter of the trunk below the bud-union. This 



seems to be a constant result of the union of the compara- 

 tively small root system, accustomed normally to develop 

 a small tree, \vith the bud of a species of large growth. Such 

 evident root stimulus appears in the trifoliate stock irrespec- 

 tive of the variety of orange or lemon budded upon it. In 

 the case of the latter the increase of trunk persists even when 

 the counter effect results in the dwarfing of the tree. 



'It must be pointed out in conclusion that this Station, 

 despite the favourable results so far obtained with the 

 trifoliate orange as a stock for oranges, cannot recommend 

 it at present, in view of the fact that well-defined cases are 

 known where its use has been injurious. In the absence of 

 further knowledge, with the limited data at hand, the use 

 of either sweet or sour stock is, therefore, to be recommended 

 on grounds of wide and successful experience of California 

 growers. Where conditions are favourable for the develop- 

 ment of gummosis, sour stock should be given the preference.' 



Teak in Trinidad.— The following note on the 

 growth of Teak in Trinidad has been received at Kew from 

 Mr. C. S. Rogers, Forest Officer. Trinidad and Tobago, with 

 some interesting photographs, showing the remarkable size 

 of the leaves and the vigour of the young trees: — 



East Indian Teak, Tectona grandis, was first introduced 

 into the plantations in the Forest Reserves in Trinidad in 

 1913. 



The seeds were obtained from the Tharawaddy, Burma, 

 through the courtesy of the Conservator of Forests, Pegu 

 Circle. 



In 1913 about 1-t^ acres were planted, 2i acres being 

 situated in the Southern Watershed Reserve, about 7 

 acres in Arinia Reserve, and -5 acres in the Central IJange 

 Reserve, In each locality the oriainal forest containing no 

 marketable timber of any consequence was felled, burnt, 

 and lined out with stakes or pickets at 10 f«et by 10 feet. 



So far the best results have been attained in the Central 

 Range Reserve Plantation where .5 acres were planted 10 feet 

 by 10 feet. Of the 2,178 picjcets thirty-five were on unplan- 

 table ground, the remaining 2,143 were sown with Teak 

 seeds in .luly (1 8 to 24). The sowing was rather late owing to 

 the impracticability of getting the area ready at an earlier 

 date. In the following .January (1914) 1,339 picket.s, at 

 which seeds had not yet germinated, were re-sown. 



At the end of March 1914, 1,7.58 Teak seedlings had 

 resulted, and some of them were 6 to 10 feet high. In the 

 following wet season the blank pickets were again re-sown. 

 At the end of March 191.5, when stock was taken, it was 

 found that there were only twelve blanks. 



Some of the plants had attained a height of 23 feet and 

 leaves were measured up to 36 inches in length by 25 inches 

 in width, the Teak being then between twentj- to twenty-one 

 months old from the date of sowing the seeds. 



In October 1915, a tree was measured and found to be 

 32 feet high with a girth of 2 feet at ground level, and KjJ- 

 inches at 3 feet, and 14i inches at 5 feet from the ground"! 

 Its age was two years and three and a half months from 

 date of sowing. 



The soil is a sandy loam of Tertiary origin. The 

 elevation does not exceed 1,000 feet. The original forest 

 contained some trees of large size, but the more valuable 

 species had been cut out, and the remainder were for the 

 most part unsaleable owing to distance from a market. 



The normal rainfall for the district is about 1 15 inches, 

 but during the last two years it has been 20 per cent, below 

 the average. 



