Vol. XIII. No. 310. 



THE AGRICULTURAL NEWS. 



93 



BOTANICAL NOTES. 



A DROUGHT-RESISTING ADAPTATION IN 



SEEDLINGS OF MAIZE. 



The following general description is given by 

 Mr. G. JI. Collin in the Journal of Agricultural 

 Research (Vol. 1, No. 4), concerning an interesting 

 variety of maize grown by the Indiana of New ^lexico 

 and Arizona, which possesses an adaptable character 

 that promises to be of economic importance m dry 

 regions where the germination of Indian corn is 

 uncertain: — 



'Throughout the western part of the Great Plains area 

 the difficulty of securing uniform germination is a serious 

 obstacle to the growing of maize, \yith the varieties 

 commonly grown, if the seed is planted at the customary 

 depth, many seeds fail to germinate from insufficient mois- 

 ture; if planted deep enough to come into contact with moist 

 soil the plants may fail to reach tlie surface. 



'The agricultural Indians of the Southwest have con- 

 tinued from prehistoric times to grow maize successfully in 

 regions where drought, and especially the absence of spring 

 rains, makes it much more difficult to start the crop than in 

 the Great Plains. A study of the varieties grown by the 

 Hopis and other agricultural Indians shows that these varie- 

 ties possess two special adaptations: (1) a greatly elongated 

 meaocotyl that permits deep planting, and (2) the develop- 

 ment of a single large radicle that rapidly descends to the 

 moist subsoil and supplies water during the critical .seedling 

 stage. 



'This indigenous type of maize seems to have attracted 

 little attention, perhaps because it has been included in the 

 popular mind with a series of inferior varieties commonly 

 known as 'squaw corn'. But the Pueblo Indians of Arizona 

 and New Me-xico have strains sufficiently productive to 

 compare favourably with improved varieties, even when 

 grown under irrigation. The peculiar adaptations of this 

 type definitely indicate its value for the semi-arid regions and 

 warrant experiments to determine the possibility of its 

 utilization.' 



Those interested in the botanical aspects of the 

 plants under consideration may be interested in a short 

 description of the morphological features of the maize 



plant, and of a germination test 

 of the Navajo maize with that 

 of Chinese and other varieties. 



The accompanying diagram 

 shows the principal parts of 

 seedling maize plant. The 

 most important from the point 

 of view of the investigation 

 under consideration is the meso- 

 cotyl. This portion of the aerial 

 axis is so termed because it lies 

 between the coleoptyle and 

 scutellum, both of which are 

 regarded as parts of a more 

 highly specialized cotyledon. As 

 already stated, it is the remark- 

 able length of this mesocotyl 

 which enables the Hopi maize 

 to be planted at extraordinary low depths in the soil (34 cm.) 

 without any damage being done to the first foliage leaf. 



V/rsr TRUB 



CoisoPTyU' 



Ml5llC3TyL\ 



KAOICLE 



*■ secohoary 

 Fig. 1. Seedling Maize. 



In the germination tests this Indian maize and the 

 ordinary kinds were planted together in series at different 

 depths ranging from 6 cm. down to 34 cm. When planted at 

 34, the ordinary maize seedlings grew up to within about 18 

 cm^ from the surface of the gtound, but could not go any 

 farther and died; whereas the Navajo maize, as already stated, 

 owing to the remarkable elongation of its mesocotyl, safely 

 reached the surface without any damage to the developing 

 bud and became firmly and satisfactorily established 



Reference has already been made to the remarkable tap 

 root which these Indian maizes possess, and taking all their 

 characteristics into consideration one is forced to the conclu- 

 sion that here is a plant of real use which may be taken 

 advantage of with great profit l>y- breeders of Indian corn in 

 different parts of the world. 



ABSORPTION OF PLANT FOOD: INFLU- 

 ENCE OF THE MEDIUM. 



The Experiiii^'.nt Statiim Record {Decetahei 19l:i) 

 publishes the following abtract of some recent work 

 done in France on the above subject. 



Continuing the above work, the author investigated the 

 influence upon the adsorptive power exerted by living as 

 well as dead roots of wheat and their absorption of nitrogen 

 on the addition of certain salts to the ammonium chlorid 

 nutritive medium. 



From these tests it is said that the other salts influence 

 strongly both diffusion into live plants and adsorption by 

 dead ones. It appears also from tabulated results that the 

 rapidity of diffusion, as observed in the series of different 

 salts, varies in nearly the same ratio as does that of adsorp- 

 tion. The results of various further experiments with 

 different concentrations of other salts in connexion with 

 ammonium chlorid are held to show that for each of the 

 former in connexion with the latter a point of concentration 

 exists, corresponding to the maximum of adsorption by the 

 roots. These facts are held to explain, at least in part, some 

 good effects on vegetation obtained by u.sing in addition to 

 ordinary fertilizer.*, such substance-s as common salt, gypsum, 

 sulphate of manganese, etc., and to indicate the possibility of 

 obtaining larger crop returns bv securing better utilization 

 of nitrogen in the nutritive solution. 



It is claimed that the absorption of either organic or 

 mineral nitrogen by young plants does not depend immedi- 

 ately and alone upon the living substance, but that it is in 

 part determined by substances contained in the roots, also 

 that, all other conditions being equal, the adsorption and the 

 activity of diffusion are proportional to the concentration 

 within limits. In solutions of equal concentrations the 

 adsorptive powers or the activity of diffusion is modifiable 

 by changes in the composition of the external medium, and 

 bears a close relation thereto. 



A couple of minor points may be noted for correction 

 in Dr. M. T. Cook's book on the diseases of tropical 

 plants, reviewed in the last issue of this journal. Sooty 

 mould of sugar-cane leaves is attributed to Cajiiiodinm 

 sp. growing in the secretions of mealybugs (Aleyrodes). 

 In the Lesser Antilles, at any rate, the insects usually called 

 mealy bugs {Pseudococcus spp.) occur only under the leaf 

 sheaths, and sooty mould is associated with Delphax 

 saccharivora. Probably owing to ambiguity in the literature, 

 Barbados is several times mentioned in connexion with 

 diseases of cacao, which is not a crop of that island. 



