Relation of boron to heart rot in the sugar beet

Sugar beet seedlings were grown in quartz sand cultures with and without borax. Symptoms of boron deficiency were carefully observed and studies were made regarding the recovery of beets afflicted with heart rot. Field-grown mother beets showing heart rot symptoms were, divided into halves and planted in quartz sand cultures, with and without borax applied at various times during the subsequent growth period. Observations were made on the types of leaves produced by these mother beets. Soil and leachate tests were made to determine the extent of absorption of boron by sugar beets and the state of solubility of the boron remaining in the soil. This was done to throw some light on the possibility of boron accumulation in the soil. From the results of these experiments the following observations were made: 1. Seedlings grown in jars receiving no borax developed characteristic deficiency symptoms as follows: a. Blackening of tips of heart leaves, followed by death of growing portion of crown. b. Shortened, twisted petioles associated with crinkled condition of heart leaves and some of outer leaves. c. Abnormally dark green and thicker leaves, accompanied by more rapid wilting under drought conditions. d. Pimpled condition of petioles in early stages, followed by breakdown in form of cross and linear checking. e. Yellowing and eventual death of outer leaves, following the death of heart leaves. f. Stunted, second growth leaves following death of first leaves. g. Breakdown of heart of beet root. h. Darkened layer under skin of root and development of surface cankers in advanced stages. i. Restricted fibrous root system. 2. The available boron content of the quartz sand and the seed was adequate to prevent the appearance of deficiency symptoms for a period of two months after the seedlings were transplanted. 3. Yields of roots were increased as much as 80% by an application of 11.9 mg of borax per 5 kg of sand in divided applications. 4. Seedlings in advanced stages of heart rot definitely recovered upon the application of 4.9 mg of borax per pot. 5. Halves of field-grown mother beets planted in quartz sand cultures without borax produced stunted leaves with marked symptoms of boron starvation, whereas the corresponding halves which received like treatment but with borax added at the rate of 2 mg per 1-gallon pot, produced a more abundant leaf growth free of deficiency symptoms. 6. Soil tests for available boron showed that a crop of sugar beets produced in pot cultures removes an appreciable quantity of boron from the soil. 7. By determining the quantity of B(2)O(3) in leachates from pot cultures it was found that it was relatively easy to remove added borax from soils by leaching with distilled water even a year after the borax was applied.