In the greenhouse, corn plants, 14 days old, were transplanted to 1-gallon, soft glass jars containing nutrient solutions. Boron levels were maintained at 0, 0.01, 0.05, and 0.25 ppm. One set of plants was grown for 3, 6, or 9 weeks at each of the boron levels, after which the boron was removed. One set at each boron level received boron to maturity. All other nutrients were maintained at adequate balanced levels.
Plants grown without boron or those at the 0.01- and 0.05-ppm. boron level did not produce ears or had very poorly developed barren ears, depending on the length of time in the boron solution. Fully developed ears were produced at the 0.25-ppm. concentration when maintained to maturity, but barren ears resulted when boron was removed earlier.
In field trials 15 pounds per acre of fertilizer borate was sidedressed in bands 18 inches wide with a hand duster, when the corn was a foot high, and resulting tissue analyzed.
Boron application resulted in increased yields and reduced the number of blank stalks, when present, on 11% of the fields tested.
It was concluded that: (1) a lack of boron can cause blank stalks and barren ears; (2), the supply of available boron must be continuous; and (3), the critical level of boron in the upper leaves appears to be in between 11 to 13 ppm.