7 8 THE WHEAT PLANT 



12 or 24 inches apart was there any considerable increase in the tillering 

 of the plants. 



On soil in a high state of fertility the number of straws produced by 

 each plant is usually twice or three times as large as these. 



" LODGING " 



On examining fields of cereals at harvest the crops are not infre- 

 quently found to be more or less " lodged " or laid, the straw being bent 

 down to the ground, usually, though not always, because the lower inter- 

 nodes are too weak to support the upper leafy portion and the heavy ears. 



This " lodging " or " laying " of the crop is of serious importance to 

 the farmer, for it reduces the yield of grain, the ears of laid crops usually 

 having many of their upper and lower spikelets barren or holding only 

 poorly developed grains. Moreover, the straw and ears are discoloured ; 

 there is also much likelihood of damage to the grain by sprouting, especi- 

 ally in a damp season, and the labour and expense of harvesting is greatly 

 increased by it. 



Crops may go down at any time after the ear is out of the upper leaf- 

 sheath, though it occurs most frequently, perhaps, in the latter half of 

 June or a little later, when the plants are leafy and the grain is filling 

 rapidly. So long as the straw is soft and green, and the cells of the nodes 

 and thick basal portions of the leaf-sheath retain their vitality, the ears of 

 a laid crop may to a greater or lesser extent regain their upright position 

 through geotropic stimulus, the straws being bent upwards at each node 

 until the uppermost internode is again vertical. Where " lodging " 

 occurs early in the season the crop may therefore suffer comparatively 

 little ; if, however, it takes place late in the season when the nodal tissue 

 is dying or dead, the straw and ears remain where they are laid. 



Crops go down usually after heavy rain or violent winds, but the 

 damage is only indirectly caused by these agents, the trouble being due 

 to (i) specific weakness of the straw, associated in some cases with a 

 natural drooping habit, and (2) to weakness of the roots, or to a root- 

 system which has little grip on the soil. Wind and rain only reveal the 

 weaknesses of the stems and roots of the crop but do not cause them. 

 Where the straw is weak, the lower internodes are usually bent or broken 

 when " lodged " ; where the root only is at fault, the plant goes down as 

 a whole, the straw being rigid and straight. 



Some varieties of wheat, especially the dense-eared forms of T. 

 vulgare, possess short stiff erect straws, which under normal conditions 

 of growth do not easily " lodge." On the other hand, many Indian and 

 Persian forms of T. vulgar e have equally short but slender straws which, 

 when the ears are ripe, assume a drooping position, and although the 

 stems are strong and elastic enough to keep the ears off the ground in 



