Effect of differentiated phosphorus and potassium fertilization on maize grain yield and plant nutritional status at a critical growth stage

Optimal nutrition of cultivated plants at critical growth stages is of great importance for the achievement of full crop yield potential. The aim of this study was to assess the maize yield response and plant nutritional status at a critical stage of growth (BBCH 17) under the most favourable and reduced fertilization with phosphorus and potassium. It was assumed that the nutritional status of maize at BBCH 17 stage significantly influenced the plant growth and yielding. The hypothesis was tested in a one-factorial trial, carried out on the maize variety Veritis in 2007-2011, which was a part of a long-term study started in 2000 according to a randomized complete block design. The factor tested comprised different phosphorus and potassium doses applied at constant levels of nitrogen and magnesium fertilization. The yields of maize significantly differed between the treatments and in relation to the control. In each year, maize responded with a lower yield to the no-phosphorus treatment when compared to the no-potassium treatment. Irrespective of the fertilization variants, the content of the nutrients tested (except iron) was below the standard value. A significant relationship was shown between the nutritional status of maize at the stage of 7 leaves unfolded (BBCH 17) and grain yield. The coefficients of determination ranging from 59% to 94% showed that, irrespective of which treatment was applied, the mineral nutrient content in maize leaves at BBCH 17 stage had the strongest influence on the maize yield.