BOTANY. 119 



BOTANY. 



Root tubercles and their production by inoculation, D. H. Otis 

 (Industralist, 24 {1898), ¥o. 6', pp. 363-378, pi. 1, Jigs. 2).— The author 

 makes a general statement relative to the presence and function of 

 tubercles on the roots of leguminous crops, and reviews the earlier as 

 well as more recent investigations relative to them. He also reports 

 investigations on root tubercle development of soy beans. 



Soy beans have been grown at the Kansas Station since 1890, but 

 frequent examinations of the roots failed to reveal the presence of any 

 tubercles on them. The author secured from the Massachusetts Station 

 a quantity of soil in which soy beans had been grown and tubercle 

 development previously noted. Two varieties, yellow and medium 

 green soy beans, were grown and different methods of inoculation prac- 

 ticed. In some of the plats a small quantity of inoculated soil was 

 placed in each hill at the time of planting. In others an extract of the 

 soil was made and this used for inoculation. The methods of culture 

 and details of growth are given, in which it appears that the rows inocu- 

 lated at the time of planting attained on the whole a little greater height 

 than those inoculated with the extract after planting; the difference, 

 however, was slight. All the inoculated plants showed a fairly uniform 

 distribution of tubercles as well as a greater diameter of the lower part 

 of the stem than the plants not so treated. Analyses of the crop 

 showed a slight increase in nitrogen, protein, and water content. The 

 yellow soy beans inoculated with the extract gave the largest yield of 

 both beans and fodder, while the medium green not treated yielded the 

 greatest quantity of beans, and the plat inoculated with soil the most 

 fodder. 



The field experiments were repeated in pots and extended to include 

 a number of varieties of soy beans, and all plants inoculated either with 

 soil or extract showed well-defined tubercles on their roots. The author 

 undertook experiments in the greenhouse to ascertain the time of 

 tubercle appearance. The first visible tubercles appeared thirteen 

 days after the beans were planted, or eight days after the plants were 

 above the ground. The effect of sterilizing the soil was noted, the 

 Kansas soil being already sterile and the Massachusetts soil having 

 been heated to 200° C. 



Experiments in which the plants were inoculated at the top, middle, 

 and bottom of pots showed that the organism producing the tubercles 

 is incapable of very great vertical distribution throughout the soil. In 

 order to secure proper distribution, a mechanical mixing of the soil is 

 necessary. Inoculation experiments, in which different amounts of 

 infected soil were used, showed no particular difference, either in the 

 development of the plants or the tubercles on the roots. The action of 

 light on the micro-organism was found to be without any appreciable 

 effect. The effect of different temperatures on the inoculating material 

 was tested, in which soil was heated to ten different points, varying from 



