Željko Jukić

Hybrid maturity influence on maize yield and yield component response to plant population in Croatia and Nebraska

Maize (Zea mays L.) yield component analysis is limited. Research was conducted in 2012 and 2013 at Zagreb, Croatia and Mead, Nebraska, United States with the objective to determine the influence of environment, hybrid maturity, and plant population (PP) on maize yield and yield components. Three maturity classes of maize hybrids were produced at five PP ranging from 65,000 to 105,000 plants ha−1 under rainfed conditions. Yield, ears m−2, rows ear−1, ear circumference, kernels ear−1, kernels row−1, ear length, and kernel weight were determined. Average yield was 10.7 t ha−1, but was variable for hybrids across PP. The early maturity-hybrids had lesser ear circumference, more kernels ear−1, greater ear length, and fewer rows ear−1 than mid- and late-maturity hybrids. Kernels ear−1 had the highest correlation with yield (r = 0.47; P < 0.01 for early-maturity hybrids; r = 0.55; P < 0.01 for the mid- and late-maturity hybrids). Path analysis indicated that ears m−2, kernels ear−1 and kernel weight had similar direct effects on yield for early-maturity hybrids (R = 0.41 to 0.48) while kernels ear−1 had the largest direct effect (R = 0.58 versus 0.32 to 0.36) for the midand late-maturity hybrids. Rows ear−1 had an indirect effects on yield (R = 0.30 to 0.33) for all hybrids, while kernels row−1 had indirect effect (R = 0.46) on yield for mid- and latematurity hybrids. Yield component compensation was different for early-maturity hybrid than the mid- and late-maturity hybrids, likely due to the proportion of southern dent and northern flint germplasm present in these hybrids.

Water release rate from corn kernel affected by cropping intensity

The average field kernel drying rate (water release rate) was not the identical in all growing seasons. Similar kernel drydown rates in the field are observed in 2002 and 2003 and they were much slower than drydown rates in the field in 2001. Although in the IPS the kernel moisture loss in the field is faster, the difference between production systems was not significant. All the hybrids, except Bc Jumbo 48, had the fastest average kernel drydown rate in 2001. Also, all the hybrids, except Bc Jumbo 48, had the fastest average kernel drydown rate in the IPS. Chosen hybrids had a significant kernel drydown rates in the field and responded differently in drydown rate under the impact of climatic conditions in growing seasons.

MINERAL COMPOSITION OF CORN PLANT MATERIAL AFTER FERTILIZATION WITH FERMENTED MEAT-BONE MEAL

Based on the conducted investigations, after a two-year research of meat-bone meal as a biofertilizer (in 8 combinations and 3 repetitions) on corn hybrids, it can be determined that the lowest plant mass was recorded in the control combination, where no fertilizer was applied, and somewhat higher plant mass was recorded in those combinations where organic fertilizers in different dosages were applied. A significant increase in plant mass was found in combinations with only mineral fertilizer applied and in combinations with half dosage of mineral fertilizer and different shares of organic fertilizer. Further, plants were larger and had larger number of leaves when treated with half-dosage mineral fertilizer in combination with different dosages of organic fertilizer, and when treated with mineral fertilizer only. The fertilizer tests with fermented MBM enable to conclude that the mineral substances content (N, P2O5, K2O, Ca and Mg) ranged in mean values both in plant material and in kernel, and different values are conditioned by total mass and ion interactions.