Boron nutrition improves peanuts yield and seed quality in a low B sandy soil

Peanuts are mainly grown in sandy soils with low boron content, which may limit the crop yield, especially runner-type cultivars that have high-yields. Boron deficiency causes hollow heart in peanut seeds, reducing yield and seed quality, but the best strategy to supply boron to peanut is still not known. This study aimed to evaluate peanuts nutrition, yield, and seed quality as a function of boron rate, source, and application form. The study was conducted for two years in sandy soils with low boron in southeastern Brazil. Treatments included application of boron via soil: control (boron unfertilized), boric acid at 1.5 kg ha-1 of B, Ulexite (1.5 and 3.0 kg ha-1 of B), and sodium tetraborate (1.5 and 3.0 kg ha-1 of B) combined with foliar fertilization (sub-plots): 0, 400, 800 and 1200 g ha-1 of B (boric acid) with four replicates. Boron fertilization via soil and foliar increased peanuts yield by 20 % (1100 kg ha-1) and 14 % (700 kg ha-1)-the average of the two crops, respectively. Combined use of soil and foliar fertilizer was justified only in years with water deficit and when the rate applied via soil was low (<3.0 kg ha-1). Boron application via soil or application of 400 g ha-1 of B via foliar fertilization increased seed germination rate by 10 to 13 %. Boron fertilization increased the percentage of normal seedlings, seedling weight, and length and reduced the germination time. Foliar and soil boron applications efficiently improved peanut seed nutrition, yield, and quality. However, soil application performed better, showing a higher percentage of yield increase.