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Abstract
The growth response of 1-year-old pecan seedlings in sand culture to various levels (0, 60, 120, 240, 615, 990, 1365, and 1740 ppm) of K was determined.
Leaves of the plants receiving no K exhibited deficiency symptoms; and those receiving 1740 ppm K exhibited toxicity symptoms. In both cases, plant dry weight was suppressed when compared to plants grown with intermediate levels of K (60 to 1365 ppm). Growth response (weight of roots, stems, and leaves) to intermediate treatments of K was normal and did not vary significantly.
In all tissues, increase in per cent K was a diminishing response to the increasing supply of K in the nutrient solution. Per cent K in the leaf or leaflet was a better indicator of K availability than K in the roots or stems. Potassium in the leaf or leaflets was equally reliable indicator of K availability, but the percentages of K associated with a given availability varied with the tissue sampled and the time of sampling. Under the conditions of this study, the data indicate that K deficiency will probably occur when K, on a leaf dry weight basis, falls to some value below 1.0%.