102 



FIELD CROP PRODUCTION 



pearance of a leafy, low-growing plant. A little later, 

 however, the internodes elongate quite rapidly, pushing 

 the nodes farther apart and lengthening the stem. Before 

 this stage begins, buds appear at the lower nodes and 

 develop by lengthening their internodes 

 into full-sized stems along with the 

 lengthening of the main stem. This is 

 called tillering or stooling. Thus one 

 seed normally produces several stems, 

 sometimes as many as a dozen or more. 

 The number of tillers produced depends 

 upon several factors. Some varieties 

 naturally produce more tillers than 

 others. Thin seeding promotes the 

 growth of a larger number of tillers 

 than a thicker rate of seeding. Winter 

 wheat usually tillers more than spring 

 wheat. Poor or infertile soils retard the 

 production of tillers. Thus it is seen 

 that many more heads or spikes are pro- 

 duced on a given area than there were 

 kernels planted, the number depending 

 upon the several factors above mentioned. 

 The length of the stem, when fully 

 grown, varies with the variety and soil. 

 Some varieties grow only 2.5 to 3 feet 

 in height, while others under the same 

 conditions may reach a height of 4 or 5 feet. Aside 

 from the variation in the length of the stem, there is 

 also found variation in the number of tillers, thickness 

 of the stem wall, and in the number of nodes. In describ- 

 ing or identifying varieties of wheat, the color of the stem, 

 particularly that of the upper internode, is of considerable 



FIG. 31. Dia- 

 gram showing stool- 

 ing or tillering in 

 wheat. 



