112 THE PEANUT— THE UNPREDICTABLE LEGUME 



to the roots has a pronounced effect on the mineral composition of the 

 foliage. A deficiency of any major nutrient element to the root zone re- 

 sulted in low values of that element in the leaves. A deficiency of potas- 

 sium gave high calcium and magnesium values of the leaves, and a de- 

 ficiency of either calcium or magnesium seemed to increase the potash 

 content of the leaves. Other workers (19, 70) have secured similar 

 results. Data of foliage analyses frequently show wide variation which 

 is to be expected since it is known that both climatic and soil conditions 

 influence the mineral content of plant leaves. 



Some data of organic constituents of peanut hay are given in table 9. 



According to Moore (59) when peanut plants were grown on a 

 range of nitrogen levels from very high to very low, the foliage con- 

 sistently increased in total sugars, starch and dextrians, while the per- 

 centage of soluble solids and total nitrogen decreased as the nitrogen 

 supply to the roots decreased. Hemicelluloses did not seem to be related 

 to the nitrogen level on which the plants were grown. He suggested that 

 total nitrogen rather than any specific nitrogen fraction should be used 

 in correlating nutritional studies of the peanut. 



FOLIAR DIAGNOSIS 



Diagnostic methods involving analytical or plant-tissue tests have re- 

 ceived considerable attention in recent years. In general, analyses of the 

 entire plant are not recommended since specific tissues are considered 

 to be more reliable as an indication of the mineral condition of the plant. 

 Leaves are frequently chosen because their nutrient content more nearly 

 reflects the supply from the soil. Standardization of tissue tests for known 

 conditions may be useful especially when values of elements below the 

 limits regarded as necessary for plant growth are the ones of interest 

 from the viewpoint of fertilisation. 



Analyses of the peanut seed are of little diagnostic value since its 

 mineral composition is relatively constant. The mineral content of the 

 shell is influenced by nutrient supply but analyses of that organ would 

 serve only as a fertilizer guide for the coming year. It would appear that 



