Physical characteristics of the grain of corn hybrid Knezha-435 depending on the system mineral fertilization

The experiment was conducted at the stationary field trail of DAI General Toshevo. Based on different fertilizer rates (0, 60, 120 and 180 N and respectively P2O5 kg/ha and potassium – 0, 60 and 120 K2O kg/ha) the dynamics of the physical characteristics of the corn grain (hybrid Knezha-435) for the period 2020-2023 was established. The research period is characterized by a very pronounced influence of meteorological conditions on the values ​​of the physical characteristics of the grain at the tested rates and ratios between NPK in the fertilizer rate. The conditions of 2022 are particularly favorable for the formation of the largest grain - an average of 290.8 g/1000 grains in combination with the highest average values ​​per hectoliter (79.6 kg). The year was characterized by increasing values ​​of the 1000 grain as a result of nitrogen fertilization – alone and in combination with PK. In the group of combinations of N180, an average value of 305.8 g was reached, and the maximum value (328.3 g) was established in the combination N180P0K60. The combination of meteorological components of 2020 and especially 2023 lead to the formation of grain with lower average values ​​- 243.3 g and 209.2 g, respectively. Increasing nitrogen rates are the reason for the decrease in the values ​​of the index. In 2021, the differentiation in the values ​​of grain size depending on the amount of nitrogen norm is significantly less pronounced compared to 2020 and 2022. The dynamics of hectoliter values ​​are influenced more significantly by the conditions of the year and less by those of norms of fertilization. It has been established that in the absence of nitrogen fertilization or when applying lower nitrogen rates, hectoliter is higher compared to the annual use of aggressive nitrogen rates.