304 Mineral Nutrition of Plants 



the calcium and magnesium content was below that of fruit from 

 more fertile fields. Acid soil conditions delayed maturity. Since high- 

 quality production occurs early in the season, extremely acid soil con- 

 ditions are to be avoided. However, certain constituents, such as avail- 

 able manganese and iron, are influenced by the acidity of the soil and 

 may indirectly influence quality. 



LOW AVAILABLE POTASSIUM AND MAGNESIUM 



A number of quality factors have been attributed to low potassium 

 content of the soil. The principal ones affected seem to be yield, as- 

 corbic acid, sugars, and potassium content. The foliage on plants with 

 potassium deficiency is rapidly lost, thus causing the fruit to be ex- 

 posed to the elements. Yellow top fruits are much more prevalent on 

 plants with potassium deficiency. The loss in processing is much greater 

 than with normal fruit. The yellow in the tissue tends to destroy the 

 brilliancy of the processed product. 



Magnesium often becomes a limiting factor in tomato production on 

 the eastern seaboard. The soil selected in this case was very poorly sup- 

 plied with both calcium and magnesium. Eighty pounds of calcium 

 oxide per acre were supplied in the fertilizer, but no magnesium was 

 added. The plants on this field broke down very badly from magnesium 

 deficiency. The fruit from these vines was poor in color and low in 

 magnesium and sugars which is characteristic of this deficiency. The 

 most important failing of a tomato plant deficient in magnesium is 

 the breakdown of the foliage, leaving the fruit unprotected from hot 

 sunshine. 



BORON IN TOMATO PRODUCTION 



Earlier in the production of tomatoes when the yields were com- 

 parably low, boron deficiency was no problem. However, beginning 

 about 1940 when the yields of tomatoes had been considerably increased 

 over the former yields, boron deficiency symptoms became increasingly 

 evident. In fact, boron deficiency became the number one problem in 

 tomato production in certain sections. Research work has established 

 the fact that on the eastern shores of Delaware, Maryland, and Virginia, 

 under average conditions, boron deficiency is likely to occur when the 



