262 Mineral Nutrition of Platits 



generalizations. I realize that generalizations can be dangerous, yet it 

 is through them that progress is made. For the purpose at hand, I 

 shall attempt to travel that narrow path between oversimplification on 

 the one hand and undersimplification by too ardent a treatment of 

 minutiae on the other. 



TRANSLOCATION ACCOMPANYING GERMINATION 



The translocation of minerals from the storage regions of the seed 

 to the developing plumule, hypocotyl, and radicle constitutes the initial 

 mineral translocation in the ontogeny of the developing plant. Accom- 

 panying the hydration of the seed there is a solution of the minerals 

 present. Most seeds contain sufficient minerals to serve the developing 

 seedling until the roots, stems, and leaves are well developed. 



During the germination of red kidney bean seeds in moist Scot 

 towels, we have observed a net loss of iron from the seeds amounting 

 to approximately 50 per cent of the total initially present. This amount 

 of iron was gained by the toweling at the expense of the seeds and, 

 therefore, was lost to the seedlings as they were removed to other media 

 after two days. At this stage the roots were not sufficiently developed 

 to reabsorb the iron from the toweling. The major portion of the iron 

 remaining in the cotyledons was readily translocated to the developing 

 plumule, hypocotyl, and radicle. This translocation parallels closely the 

 translocation of carbohydrate (Figure 1). 



These results are in good agreement with the movement of nitrogen, 

 phosphorus, magnesium, and potassium in germinating wheat seeds 

 as reported by LeClerc and Breazeale (5). This is true even though the 

 storage materials in wheat are found chiefly in the endosperm while 

 in beans the reserves occur in the cotyledons. 



Studies were made in both normal daylight and total darkness. 

 Translocation of iron, as well as carbohydrate, proceeds much more 

 slowly in darkness than under conditions of normal daylight (alternat- 

 ing night and day). Both Whitmore (10) and Withrow (//) have re- 

 ported somewhat similar results. It is clearly indicated that light exerts 

 an influence on the rate of translocation of both reserve foods and iron 

 from the cotyledons into the developing plant axis. The mechanics of 

 this efTect is unknown at present. 



