Zinc is essential for the growth and development of plants, but in excessive amounts in the soil it can be toxic for them. Its mobility depends in part on the organic matter content of the soil. The aim of the study was to investigate the effect of application of increasing amounts of zinc (200, 400 and 600 mg Zn·kg−1 of soil) together with various forms of organic fertilizer (cattle manure, chicken manure and spent mushroom substrate) on the yield of cocksfoot and the content and uptake of this metal, and to determine its bioaccumulation factor and tolerance indices. A minor effect of zinc on cocksfoot, expressed as a decrease in yield, was observed following the application of 400 mg Zn·kg−1 of soil. Increasing application to 600 mg Zn·kg−1 caused a significant decrease in yield. Application of 400 and 600 mg Zn·kg−1 of soil significantly reduced the value of the Zn/Org tolerance index. Increasing levels of zinc application increased its content and uptake by cocksfoot and reduced the bioaccumulation factor in the plants. All of the organic materials applied increased the yield of cocksfoot and its uptake of zinc. Spent mushroom substrate increased the Zn/Org tolerance index, while cattle manure and chicken manure increased the Org/Zn tolerance index, which confirms their protective action against high zinc content in the soil.
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