Without irrigation, the 2021 average yields of the long-term maize experiment in Debrecen-Látókép were significantly lower than the respective averages of the previous years. On the irrigated plots, the yield level was significantly higher, at the level of an average crop year.

The winter period preceding the growing season did not show any notable extremes, with temperatures and precipitation being in line with the long-term average.

From the beginning of April to the end of May, the weather was characterised by a relatively steady and continuous significant negative temperature anomaly. April was 3.0 °C cooler than the long-term average, and May was 2.1 °C cooler. The daily mean soil temperature values only rose steadily above the plant base temperature (10 °C) from 19 April. The earliest sown maize emerged by the end of April. Development of the emerged crops was also slow. Average rainfall in May still provided adequate water supply for maize. Early June saw a marked change in the weather pattern. The first two months of summer were sunny and much warmer than usual, with very little rainfall. The temperature anomalies in June and July were +2.8 °C and +2.6 °C respectively. The 10 mm of precipitation in June is almost negligible at these temperatures, and by the end of the month, a severe drought situation had gradually developed. July was also very dry (30 mm of precipitation), with drought intensifying during critical phenological phases. In some stands, flowering and fertilisation problems were observed, manifested by a higher proportion of infertile plants and ears with incomplete grain patterns.

Drought conditions continued in August (32 mm) and September (19 mm) with temperatures returning to near average. This provided the necessary conditions for the grain to release water and dry.

There were periods of the growing season with favourable weather for maize, but the severe summer drought resulted in a very unfavourable year with very high yield losses in the production areas of the region of Hajdúság. This highlights the growing importance of irrigation in the future and the need to improve irrigation.

Keywords: weather, rainfall, temperature, maize, average yield