AGRICULTURAL BOTAXY, CHEMISTRY AND PHYSIOLOGY OF PLAXTs Q55 



established by the researches of Dehe;rain, Mox^voisix" and Kosorotox', 

 that there is a relation between the depth to which plants extend their roots 

 and their resistance to drought. Assuming, therefore, within the lim- 

 itations of a given species, the plants most resistant to drought are those 

 which possess among other things a root system carried to a greater depth, 

 stress is laid on the need for the following : 



i) Statistical investigations of the depth reached by the roots of 

 all plants, cultivated and wild, of interest to agriculture ; 



2) Investigations into the " metric differences " (i. e. in length and 

 weight) of the root system of the different species and varieties of cultivat- 

 ed plants. 



3) Investigations into the fixation and the increase b}' selection of 

 the power of deep root growth. 



Investigations into the Root System of Oats, Wheat, Flax axd 

 Peas. — These were carried out in 1914, in wooden boxes of 2 different 

 sizes : (i) big boxes with 0.162 square metres base area (0.18 X 0.09m.) and 

 1.77 m. in height, used for plants which were brought to maturity ; (2) Small 

 boxes (0.162 sq. metres base area and o. 88 m. height) for the plants removed 

 in the 1st phase of vegetation. The soil was taken from the upper strata of 

 the fields of the Institute. The roots were washed by a jet of water de- 

 livered by a pump, and afterwards numbered and straightway put into 

 formalin where they remained until the winter, when they were dried and 

 studied. 



The plants taken out of the formalin were washed with water to re- 

 move any disagreeable smell, afterwards dried on cardboard, and their 

 aerial and underground parts were then measured and weighed separately 

 for each box. The roots for successive soil layers of 25 cm were also measur- 

 ed, in order to determine the amount of roots in each layer. The result- 

 ing data were divided by the number of plants in each box, and this result 

 multiplied by 100, so as to reduce all measurements to one unit, the weight 

 of 100 individuals. The measurements of the length of the aerial and un- 

 derground parts were alone taken in calculating the maximum, but they 

 are sufficient in view of the preliminary nature of the investigations. 



At the beginning of June there were sown : 10 varieties of oats, 8 of 

 spring wheat, 4 of flax and 3 of peas; for each variety 4 boxes were 

 used, 2 large and 2 small, so as to have 100 tests in all. The seeds were 

 taken exclusively from the pure lines obtained at the selection Station of 

 the Agronomic Institute of Moscow, because the preliminary studies car- 

 ried out with commercial oat seeds had given very divergent results as re- 

 gards downward growth of the root system. In this ccnnection mention 

 may be made of the tests in the open field carried out by the writer in 1915, 

 with pure lines of flax, at the flax selection Station. The depths of the roots 

 for a given line was studied in a considerable number of individuals (lOO) 

 and over an area of some square metres ; it was found that the maximum 

 depth and spread of the roots in the different soil strata was everywhere 

 the same; the maximum depth of the roots ranged from 44 to 53 cm. between 

 one plot and another. In other words, tests have shown that there is a 



