Boron deficiency in soybeans

A deficiência de boro é rara na cultura da soja no Brasil. A deficiência aqui descrita ocorreu em Guaíra, SP, numa várzea onde houve excessiva aplicação de calcário, elevando a saturação por bases a valores próximos de 90%. Nas áreas deficientes, o teor de boro no solo foi de 0,06 ppm e nas áreas aparentemente sem sintomas, 0,11 ppm. Nas folhas das plantas com sintomas, a concentração era de 10 ppm de boro e nas sem sintomas, de 19 ppm. Nas plantas deficientes, as folhas primárias eram coriáceas e espessas, e houve morte da gema apical, com brotamento de gemas laterais, nanismo, poucas flores e pequeno pegamento de vagens, com sensível redução na produtividade. Boron deficiency is not usual in soybean crop in Brazil. The observation reported in this article occurred at Guaíra, State of Sao Paulo, Brazil on a low flat excessively limed and high in organic matter land. The soil boron content in the areas with plant deficiency was 0.06 ppm while in the areas of apparently healthy plants the soil boron content was 0.11 ppm extracted with boiling water. The leaf concentration for deficient and healthy plants was 10 and 19 ppm respectively. Primary leaves of deficient plants were leathery and thick and there was death of the apical buds. There were few flower formation and pod setting. The boron deficient plants were dwarf with thick stems creating difficulty at harvest and soybean yield was considerably reduced.