Evaluation of the nutritional status of zinc and other micronutrients in maize at the critical growth stages is an important diagnostic and prognostic factor that plays a substantial role in shaping its final yield. A hypothesis was verified that the application of different phosphorus and potassium fertilization doses affected the nutritional status of zinc in maize at the critical growth stages: leaf development (BBCH 17) and flowering (BBCH 65), as well as the zinc accumulation at the stage of ripening (BBCH 89, fully ripe). A single factor field study was conducted for 5 consecutive plant growing seasons (2007-2011). The results showed that mineral fertilization significantly increased zinc concentration in maize leaves at BBCH 17 and BBCH 65 growth stages. Regardless of the effects of the experimental factor, the Zn leaf content in maize at both critical growth stages was much below the standard value. Although the zinc concentration observed at the leaf development stage was low, no significant relationship was found between the zinc nutritional status in maize at that time and the subsequent grain yield. Stronger relationships between the zinc nutritional status in maize and grain yield were observed at the flowering stage. The total accumulation of zinc in maize was significantly differentiated by the experimental factor. The chemical form of phosphorus applied had no significant effect on Zn content in maize at the critical growth stages as well as on the accumulation of this nutrient in fully ripe plants. The ZnHI value obtained in the control treatment was 51.7%, whereas the values achieved in fertilizer treatments were higher and ranged from 52.9% (W100 PAPR – with partially acidulated phosphate rock) to 57.3% (W25 - 25% of K and P recommended rate). Correlation analysis on maize yield and zinc accumulation showed that yield volumes were determined most strongly by zinc accumulation in maize vegetative organs (especially husk leaves).    

22.4.2016