Abstract

Experiments were conducted to determine the use of certain organoborates as potential sources of B for plant nutrition and to assess the sensitivity to them by different crop species. Of particular interest was sodium tetraphenylboron (NaTPB), a specific precipitant for radiocesium. For comparison, the inorganic source of B, boric acid (BA), was used as the control source of B. Greenhouse experiments indicated the following: (i) BA and NaTPB produced similar toxicity symptoms in the various crops studied; (ii) the order of sensitivity to NaTPB for various species followed the usual order for B toxicity, i.e., members of the bean (Phaseolus spp.) family are most sensitive, whereas cereals and chard (Beta vulgaris L.) were least sensitive; (iii) crop dry matter yields can best be predicted by the applied soil B on a coarse-textured soil than by the plant B concentration; and (iv) at the same B level added to soil, NaTPB was more deleterious to plant growth than BA. A germination study indicated that at equal levels of B in substrate solution, the organo-borates, NaTPB, and diphenylboric acid were more injurious than BA to root and shoot growths, providing more conclusive evidence that the organic constituents of these compounds are also phytotoxic.

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