458 Mineral Nutrition of Plants 



The most dominant factor here is sheath moisture. Sunlight asserts 

 itself as another dominant factor. Age is also more important than here- 

 tofore. The nitrogen level assumes importance but curiously enough is 

 negative in its influence, as are soil moisture and maximum tempera- 

 ture. The rate of leaf emergence, total sugars, and minimum tempera- 

 tures are not significantly related to the girth of the stalk. 



TABLE IV 

 Partial Regression of Certain Factors on the Rate of Leaf Emergence 



(" = J 373) 



Factor 



Beta 



"/" Value 



Minimum temperature (°F.) 



A S e . 



Maximum temperature (°F.) 



Soil moisture 



Light 



Leaf nitrogen 



Sheath moisture 



In Table IV is reported the analysis of the factors affecting the rate 

 of leaf emergence. Leaf production provides the plant with its meri- 

 stems and additionally is a measure of the plant's vigor. As might well 

 be expected, age is a dominant factor and is, of course, negative. Both 

 day and night temperatures are dominant. Soil moisture here assumes 

 a very important role. In fact, it appears that after the plants have used 

 up about two-thirds of the available water there is a striking retarda- 

 tion of leaf emergence and elongation as well. Light intensity and the 

 nitrogen level are also important factors in leaf emergence and vigor. 

 Sheath moisture which has been a dominant factor in all the categories 

 of growth is not significant here. 



Thus far we have been determining the weight of factors affecting 

 the growth and vigor of sugar cane. Since the sheath moisture and nit- 

 rogen levels are two practical keys to the manipulation of the physio- 

 logical status of the plant, a measure of factors affecting these levels 

 is worth while. In Table V the analysis of factors affecting the level of 

 sheath moisture is given. 



