THE RESPONSE OF MAIZE (ZEA mays L.) GRAIN YIELD TO WATER AND NITROGEN SUPPLY IN AN EASTERN CROATIAN ENVIRONMENT

During the 3-year study, maize (Zea mays L.) production in the eastern Republic of Croatia suffered great losses due to periods of flood (2010) and drought (2011 and 2012). An excessive amount of water as well as lack of it caused variation of yield and efficiency of irrigation scheduling. Irrigation treatments included a rainfed treatment and irrigation up to soil water content 80-100% of field capacity. The nitrogen fertilization treatments were 0 (control) and 200 kg N ha(-1). The analysed crop productivity parameters were 1000-grain mass and grain yield, in two hybrids. The irrigation significantly increased maize grain yield in dry years, while in the extremely wet year of 2010 yield in the irrigated plot was reduced doe to stress caused by excessive rainfall and over-irrigation. Both tested hybrids responded positively to the combination of nitrogen fertilizer and irrigation. Regardless of whether expressed on a fresh tissue or dry weight basis, the proline content in maize leaf did not show a clear effect of irrigation treatment, whereas nitrogen fertilization stimulated this amino acid accumulation. There was a close relationship established between proline in leaf dry matter in both growth stages and 1000-grain mass, as well as a weak relationship between this parameter at flowering and final grain yield. Copyright (C) 2017 John Wiley & Sons, Ltd.