663 



thus confirmed. The weakness of the stalks, which conditions the falling 

 over in lodging is found actually in the lower stem members and the second 

 internode (reckoned from the base of the stalk) is the one usually bent over. 



To be sure, the first, lowest stem member is also weak, but, as a rule, it 

 is too short to bend over ; on the other hand, the second is the most elongated 

 and the least thickened. The cells of this internode in lodged grain show a 

 considerable over-elongation and scanty thickening in proportion to the 

 corresponding cells of the normal stem. This deficient thickening is espe- 

 cially noticeable in those cells which, in the blade, fill the space between the 

 outer membrane and the vascular bundle sheath, and actually conditions the 

 firmness of the stalk. 



Lodging of grain, therefore, is produced when the lower internodes of 

 closely planted grain are insufficiently lighted. Too great shading also acts 

 disadvantageously in the very early developmental stages of the plant by the 

 over-elongation of the cells and the scanty thickening of the walls, which, 

 as said above, takes place usually in the second internode from the bottom. 

 This bad condition will occur more strongly in the places in the internodes 

 where the leaf sheath surrounds the stalk most closely. This takes place 

 near the base of the stem and the phenomena of etiolation are found most 

 clearly and intensively here. 



Formerly a lack of silicic acid was assumed as one reason for the 

 lodging of grain. This may now be explained as erroneous, since it has 

 been shown by water cultures of grain plants, that minimal amounts of 

 silicic acid are sufficient to produce a normal plant and since analyses of 

 lodged grain, compared with grain which had not lodged, have shown but 

 little difference in silicic acid content. In normal plants also, as Pierre has 

 shown for wheat and Arendt for oats, the lowest internodes of the stalk 

 are the poorest in silicic acid, of which the greatest quantity in any case is 

 found in the leaves. These can be 7 to 18 times as rich in silicic acid as 

 the lower stem members. 



Connected with the lack of light is the second point, given as a cause 

 for lodging, namely, that the disease may be traced to an excessive supply 

 of nitrogen in the soil. At any rate, this is one cause inasmuch as a too 

 luxuriant development of the leaf apparatus is thus produced, essentially 

 increasing the shading. Such a cause is given, however, by every circum- 

 stance which conditions a too thick stand from the seed, i. e., for example, 

 too abundant seeding, too abundant water supply, etc. 



Experiments made by Ritthausen and Pott^ show the change in the 

 maturing of fruit due to different nitrogen fertilizers and the tendency of 

 the plant to lodge. While the grains of summer wheat are well matured with 

 an abundant supply of nitrogen but remain small and glassy hke the seed, the 

 grains from plots not fertilized with nitrogen, lodge after less heavy rain- 

 storms. Kreusler and Kern confirmed the above statements'. We may 



1 Landwirtsch. Versuchsstationen 1873, p. 384. 



2 Centralbl. f. Agrlkulturchemie 1876, I, p. 401. 



