Uticaj tipa zemljišta i količine azota na produktivnost hibrida kukuruza različitih FAO grupa zrenja

A three - year trial (2005 - 2007) was conducted with the objective of studying the influence of soil type (chernozem and brown forest soil), nitrogen rates (no N control variant, PKNfon, PKN60, PKN120 and PKN180) and hybrids of different maturity classes and length of vegetation period (ZPSC 434, ZPSC 578 and ZPSC 677) on morphological and yield properties, yield components and grain yield, water content in grain, nitrogen content in leaf and grain, nitrogen uptake including corn grain quality properties. During corn seed sowing but also in the phases of corn cob flowering and the physiological maturity of grain, both the dynamics of the microbiological activity and that of mineral nitrogen in soil were monitored to a depth of 30 and 90 cm respectively. Field experiments were carried out under the agroecological conditions of eastern Srem (Zemun - Polje) and central Šumadija (Rača Kragujevačka) using a split - plot design in four replications. Based on the results obtained the overall number of microorganisms, actinomycete and Azobacter sp. was greater in the chernozem soil type. The number of fungi was greater in the brown forest soil type. The most stimulative with regard to the total number of microorganisms, number of actinomycetes and Azotobacter sp. was nitrogen added at the rate of 60 kgha-1. Nitrogen applied at the rate of 180 kgha -1 mostly tended to inhibit the investigated groups of microorganisms. The number of fungi varied unevenly depending on the nitrogen rate employed. The overall number of microorganisms was greater in soil samples from fallow land compared with corn - sown land In all the three trial years the amount of mineral nitrogen was greater in chernozem compared with the brown forest soil type. The amount of mineral nitrogen was the smallest in the no N control variant of both fallow and corn - sown soil samples. Increasing the rate of fertilizer nitrogen tended to increase the content of mineral nitrogen in soil, but also the amount of nitrogen uptake by hybrid corn plants. Fertilization was found to contribute to greater amounts of mineral nitrogen in brown forest soil than in chernozem soil type...U trogodišnjem periodu (2005 – 2007. godine) vršena su istraživanja uticaja tipa zemljišta (černozem i gajnjača), količine azota (kontrola – bez đubrenja, PKNfon, PKN60, PKN120 i PKN180) i hibrida različite dužine vegetacionog perioda (ZPSC 434, ZPSC 578 i ZPSC 677) na morfološke i produktivne osobine, komponente prinosa i prinos zrna, sadržaj vode u zrnu, sadržaj azota u listu i zrnu, iznošenje azota prinosom zrna, kao i na kvalitativne osobine zrna kukuruza. Osim toga, u periodu pre setve kukuruza, kao i u fazama cvetanja klipa i fiziološke zrelosti zrna praćena je dinamika mikrobiološke aktivnosti zemljišta do dubine od 30 cm i dinamika mineralnog azota u zemljištu do dubine od 90 cm. Ispitivanja su obavljena putem poljskih mikroogleda u agroekološkim uslovima istočnog Srema (Zemun Polje) i centralne Šumadije (Rača Kragujevačka) metodom razdeljenih parcela (split plot) u četiri ponavljanja. Dobijeni rezultati pokazuju da je u zemljištu tipa černozem utvrđena veća ukupna brojnost mikroorganizama, brojnost aktinomiceta i Azotobacter sp., a u gajnjači veća brojnost gljiva. Dopunska ishrana azotom u količini od 60 kgha-1 delovala je najstimulativnije na ukupan broj mikroorganizama, brojnost aktinomiceta i Azotobacter sp. Đubrenje azotom u količini od 180 kgha-1 delovalo je, uglavnom, inhibitorno na posmatrane grupe mikroorganizama. Brojnost gljiva varirala je nepravilno u zavisnosti od količine azota. Veća ukupna brojnost mikroorganizama ustanovljena je pod ugarom u poređenju sa uzorcima zemljišta pod usevom kukuruza. U svim godinama istraživanja, u černozemu je izmerena veća količina mineralnog azota u zemljištu u odnosu na gajnjaču. Najmanja količina mineralnog azota utvrđena je u kontrolnoj varijanti, i pod ugarom i pod usevom kukuruza. Sa povećanjem količine azota iz đubriva povećavao se i sadržaj mineralnog azota u zemljištu, kao i usvajanje azota od strane biljaka hibrida kukuruza. Povećanje sadržaja mineralnog azota u zemljištu pod uticajem đubrenja ispoljilo se snažnije u gajnjači u poređenju sa černozemom..