Grain yield is the primary trait of interest in maize breeding programs. Worldwide, drought is the most pervasive limitation to the achievement of yield potential in maize. Drought tolerance of maize has been considerably improved through conventional breeding. Traditional breeding methods have numerous limitations, so development of new molecular genetics techniques could help in elucidation of genetic basis of drought tolerance .In order to map QTLs underlying yield and yield components under drought 116 F3 families of DTP79xB73 cross were evaluated in the field trials. Phenotypic correlations calculated using Pearson’s coefficients were high and significant. QTL detection was performed using composite interval mapping option in WinQTL Cartographer v 2.5. Over all nine traits 45 QTLs were detected: five for grain yield per plant and 40 for eight yield components. These QTLs were distributed on all chromosomes except on chromosome 9. Percent of phenotypic variability determined for the identified QTLs for all the traits was in the range from 27.46 to 95.85%. Different types of gene action were found for the QTLs identified for analyzed traits. [Projekat Ministarstva nauke Republike Srbije, br. TR31068

This study concerned the effect of different intercropping systems (alternating rows and alternating strips) of maize and soybean compared with single cropping, in combination with different fertilisers (biofertiliser, organic fertiliser, and urea) on the potential availability of magnesium (Mg), iron (Fe) and zinc (Zn) from grain, through their ratio with phytate (as inhibitor) and β-carotene (as promoter). The higher grain yield and land equivalent ratio obtained under alternating rows + biofertiliser treatment demonstrated the improved ability of crops in close proximity for better utilisation of existing agro-ecological conditions. Alternating rows + organic fertiliser decreased the molar ratios phytate : β-carotene, phytate : Fe, phytate : Mg and phytate : Zn, indicating increased availability of the mineral elements in both crops. However, alternating strips + organic fertiliser contributed mostly to an increase in β-carotene, Mg, Fe and Zn concentrations in soybean. Increased grain yield of both crops was followed by decrease in β-carotene and increase in phytate, particularly in maize. In soybean, β-carotene could be considered as the main contributor to Fe availability. Accordingly, cropping in alternating rows or strips, combined with biofertilisers, could serve as fortification measures for improved nutritional quality of maize and soybean grain, without grain yield losses.

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An analysis of peroxidase and ascorbate oxidase activity, phenolic content and antioxidant capacity of isolated maize root cell walls was performed in controls and plants stressed with polyethylene glycol (PEG) or heavy metals, zinc or copper. Peroxidase activity (oxidative and peroxidative) was more pronounced in the ionic than in the covalent cell wall fraction. PEG induced an increase and Zn(2+) a decrease of both ionically bound peroxidase activities. In the covalent fraction, Cu(2+) decreased oxidative and increased peroxidative activity of peroxidase. Isoelectric focusing of ionically bound proteins and activity staining for peroxidase demonstrated increased intensities and appearance of new acidic isoforms, especially in Zn(2+) and PEG treatments. Most pronounced basic isoforms (pI ~ 7.5) in controls, decreased in intensity or completely disappeared in stressed plants. Ascorbate oxidase activity was significantly increased by PEG and decreased by Zn(2+) treatments, and highly correlated with peroxidase activity. Antioxidant capacity and total phenolics content increased in heavy metal-treated and decreased in PEG-treated plants. Analysis of individual phenolic components revealed p-coumaric and ferulic acids, as the most abundant, as well as ferulic acid dimers, trimers and tetramers in the cell walls; their quantity increased under stress conditions. Results presented demonstrate the existence of diverse mechanisms of plant response to different stresses.