BORON AND MOLYBDENUM NUTRITION OF WHEAT, BARLEY AND OATS GROWN IN PRINCE EDWARD ISLAND SOILS

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Abstract
In a greenhouse experiment, an application of 0.25 ppm B to a sandy loam soil resulted in significant yield increases of kernels of wheat, barley, and oats. Yields of barley and wheat decreased at 0.5 ppm applied B, and those of oats at 1 ppm added B. Barley was most sensitive, oats the least, and wheat intermediate to B toxicity. Boron toxicity symptoms in barley were characterized by severe brown spotting and burning of older leaf tips, while in wheat and oats the leaf tips were bleached. A boron concentration of less than 5 ppm in boot stage tissue was in the deficiency range, while a level of 6 to 10 ppm was in the sufficiency range. In wheat and barley, a B concentration of greater than 16 ppm, and in oats of greater than 35 ppm, was indicative of toxicity. The B content of straw proved to be a good indicator for detecting B sufficiency. A survey of fields from Prince Edward Island (P.E.I.) showed a range in B concentration of boot stage tissue from 0.5 to 9.9 ppm in barley, 1.1 to 6.0 ppm in wheat, and 0.5 to 5.8 ppm in oats. Under greenhouse conditions, no response to added Mo was found. Applications of 0.25 to 0.5 ppm Mo to the soil reduced yields of wheat and barley. Optimum levels of Mo in the boot stage tissue were 0.09 to 0.18 ppm in barley and wheat, and 0.22 to 0.28 ppm in oats. Sufficiency levels in kernels were 0.16 to 0.20 ppm for wheat, 0.26 to 0.32 ppm for barley, and 0.33 to 0.50 ppm for oats. In general, Mo concentration of 0.08 to 0.19 ppm in cereal straw was considered to be in the sufficiency range. The Mo concentration of boot stage tissue from survey samples ranged from 0.04 to 0.34 ppm in barley, 0.04 to 2.37 ppm in wheat, and 0.06 to 0.60 ppm in oats.

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