Harry F. Clements 455 



It is apparent that a very high proportion of the variation has been 

 accounted for and that a growth-unit equation predicting yields is 

 possible as we shall see later. The two dominant factors are the green 

 weight of the sample and the rate of leaf emergence. The factor, leaf 

 emergence, is in reality a measure of the plant's vigor and the morpho- 

 logical mechanism of growth. The green weight of the sample again 

 is a measure of the plant's vigor and its girth. 



TABLE I 

 Partial Regressions of Certain Factors on Growth Units 



(" = 1373) 



Factor Beta "t" Value 



Green weight of sheaths 



Rate of leaf emergence 



Maximum temperature (°F.) 



Minimum temperature (°F.) 



Sheath moisture 



Age 



Total sugars 



Soil moisture 



Light 



Leaf nitrogen 



Note: Definition of symbols — «, number of observations; Beta, partial regression; 

 *significant (5 in 100); ** highly significant (1 in 100); R, multiple correlation coefficient. 

 These symbols are used in Tables I— VII in this chapter. 



The next two dominant factors are the maximum and minimum tem- 

 peratures. The higher the day and night temperature, the faster the 

 growth rate, other things being equal. This relationship agrees very 

 well with our general experience, although there is a possibility that in 

 a few areas in the islands the maximum temperatures become excessive. 



Sheath moisture is the single plant component which achieves high 

 statistical significance as a growth factor. It is dominant over the nu- 

 trient material, nitrogen, and also over potassium and phosphorus. 

 Experiments have shown us that where the potassium index is 2.25 or 

 above and the phosphorus index is at 0.080 or above, no increases in 

 growth are obtained by application of these two materials. In these 



