Influence of irrigation and nitrogen fertilization on yield and quality of maize (Zea mays L.) grain

Trogodišnje istraživanje (2010./2012.), provedeno je kao stacionarno istraživanje utjecaja navodnjavanja, gnojidbe dušikom na urod i kvalitetu zrna hibrida kukuruza na Poljoprivrednom institutu u Osijeku. U Istraživanju su korištene tri varijante navodnjavanja i gnojidbe dušikom, po split split-plot shemi u tri ponavljanja. Navodnjavanje je provedeno u tri razine: A1 = kontrola (suho ratarenje), A2 = 60-100% poljskog vodnog kapaciteta (PVK) i A3 = 80-100% PVK. Gnojidba dušikom provedena je u tri razine: B1 = kontrola (0 kg N ha-1), B2 = 100 kg N ha-1, B3 = 200 kg N ha-1. U istraživanju su korišteni hibridi kukuruza (FAO 500 i 600), C1= OSSK596, C2 = OSSK617, C3 = OSSK602 i C4 = OSSK552. Urod zrna kukuruza varirao je ovisno o godini istraživanja (vremenski uvjeti) i razinama čimbenika. U sušnim godinama (2011. i 2012.) najviši urodi zrna ostvareni su na varijantama na kojima je razina vode u tlu 80 do 100% PVK i najvećom količinom gnojiva (100 kg N ha-1). U ekstremno kišnoj godini (2010.) najviši urod zrna ostvaren je na kontrolnoj varijanti navodnjavanja, a rastao je povećanjem količine dodanog N gnojiva. Sadržaj proteina u zrnu smanjen je povećanjem sadržaja vode u 2010. i 2012. god. Sadržaj škroba i ulja u zrnu rastao je u objema varijantama navodnjavanja. Najizraženije povećanje sadržaja škroba zabilježeno je u 2012. god. Porastom količine dodane vode rasla je hektolitarska masa kukuruza dok je apsolutna masa smanjena. Gnojidba dušikom vrlo značajno je povećala urod zrna, sadržaj proteina u zrnu te hektolitarsku i apsolutnu masu. Utvrđen je vrlo značajan učinak genotipa na sva ispitivana svojstva tijekom trogodišnjeg istraživanja.The three year’s research (2010 - 2012), conducted on a trial field of the Institute of Agriculture in Osijek, is a part of a long stationary experiment. The field examined was the impact that irrigation (A), nitrogen fertilization (B), and the genotype (C) had on the yield, and the quality of maize hybrids (Zea mays L). The irrigation was conducted in means of three variants, A1 being the control variant. In A2 variant the capacity of soil water content was held on 60 - 100% level of the filed water capacity (FWC), while in the A3 variant the soil water content was held on a 80 to 100% FWC. Nitrogen fertilization was conducted in three variants, B1 being the control variant (0 kg N ha-1). In B2 variant 100 kg N ha-1 was added, while in B3 variant 200 kg N ha-1 was added. Four maize hybrids (FAO 500 and 600) were used in the research, C1 = OSSK596, C2 = OSSK617, C3 = OSSK602 and C4 = OSSK552. Statistically meaningful differences of yield in all three years of research were established. Yield grew as the irrigation norm was increased, with an exception of year 2010, when the highest yield was achieved on control plots. The most distinctive impact the irrigation had on maize yield was during the very warm and very dry vegetation period of the year 2012. The amount of protein in grain was reduced by increasing soil water content. In opposition, the amount of starch and oil in the grain grew in both irrigation variants. With the increase of the water added, the hectoliter mass of maize grew, while the absolute mass was decreased. Nitrogen fertilization significantly amplified the grain yield, the protein amount, as well as the hectoliter and absolute. It was established that the genotype had a highly significant impact on all three characteristics. The course and the strength of correlation references between the characteristics (in relation to one another), and the components of the research differed in means of the years of research, most of all on account of the weather conditions in the year 2010