RESPONSE TO COPPER AND OPTIMUM LEVELS IN WHEAT, BARLEY AND OATS UNDER GREENHOUSE AND FIELD CONDITIONS

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Abstract
Experiments were conducted on a Charlottetown fine sandy loam soil under greenhouse and field conditions to determine the optimum levels of Cu in cereal crops. An application of 0.5 ppm Cu to the soil, under greenhouse conditions, resulted in percent yield increases of about 38, 180 and 500 for kernels of wheat, barley and oats, respectively. Under field conditions, Cu application, in general, did not affect the kernel yield or the weight of 1000 kernels of any of the three cereal crops. Under greenhouse conditions, without applied Cu, wheat and barley heads were 10 to 14 days later in emerging. For maximum yields under greenhouse conditions, the optimum content of Cu in plant tissues at the boot stage was 3.2 to 3.3 ppm for wheat and oats, and 4.8 ppm for barley. A Cu content of 2.3, 2.0 and 1.8 ppm in wheat, barley and oat kernels, respectively, appeared to be sufficient. For straw, a Cu content of 3.9, 3.0 and 2.3 ppm in wheat, barley and oats, respectively, appeared to be adequate for optimum growth of the crops. In general, the Cu content of kernels from field tests was higher than that of kernels from greenhouse tests. Under field conditions, Cu applications did not increase the Cu content of either the boot stage tissue or of the kernels. The results indicated that exchangeable (oxalate-extractable) Cu content of about 1.2 to 1.8 ppm in soil is indicative of Cu deficiency for growing cereal crops under greenhouse conditions.