Characterization of Boron Deficiency in Soybeans

Boron‐deficient soybean roots have a rosette appearance at the terminals caused by the death of the root primordium and the initiation of new root primordia. The root tips show some darkening, swelling, and then a collapse of the tissue. The petiole s of B‐deficient plants are very brittle. Physiologically, B‐deficiency in HA‐soybeans does not appear to involve an interference in the transport of photosynthate (C14 distribution) or precursors required for citrate synthesis in the roots. More Ca 45 was found in the tops of B‐sufficient than B‐deficient plants, but the opposite trend existed in the root sap. Boron deficiency symptoms were accentuated by maintaining a relatively low pH of the prenutrient solution by the addition of K salts.