The total area under cereals during 2018 remained at a long-term stable level of about 1.7 million hectares. Maize and wheat are the most important crops grown in the Republic of Serbia. In the structure of harvested areas under cereals, maize dominates (53%), followed by wheat (38%). The objective of this paper was to determine if there was a recognisable trend line for the production of these crops in the 2007-2018 period. The yield data (Area harvested (ha), Production (tonnes), Production (t/ha)) were collected from the Statistical Office of the Republic of Serbia. Calculations of relevant and valid trends using central tendency measures, dispersion measures, relative ratios and percentage growth were used for statistical data processing. During the observation period, the average annual growth in maize yield was 6.38%, while the average annual growth in wheat yield was slightly lower, 2.00%. However, it is not possible to create an appropriate trend line for any of the variables in order to predict a future time period, since the coefficient of determination is low.

Widespread usage of intercropping systems has been limited because of a lack of knowledge about the key factors that affect the performance of intercrop components. We used general linear modelling to explain the effect of different cropping systems on the relationships among yield, thousand kernel weight (TKW), and crude protein of cereal crops under the same agro-ecological conditions and naturally occurring inocula of obligate pathogens. The results of our study showed that the yield variation under extreme fluctuations in climatic conditions could be lowered through intercropping cultivation. The disease indices of leaf rust and powdery mildew were highly dependent on the type of cultivation. The relationships among the levels of pathogenic infection and yield performances were not straightforward and were highly dependent on the yielding potentials of the cultivars. Our study indicated that changes in yield, TKW, and crude protein, as well as their relationships during intercropping cultivation, were cultivar specific and, therefore, not the same among all cereal crops exposed to the same agro-ecological conditions.

Tracking the distribution of Fusarium species and the detection of changes in toxin production provides epidemiological information that is essential for Fusarium head blight (FHB) management. Members of Fusarium graminearum species complex (FGSC) were characterized using species and trichothecene-specific primers. Associations between members of the FGSC, cereal crop species (wheat, rye, triticale, and oat), seeding time (winter and spring), type of cultivation (monocrop and intercrop) and chemotype grouping were investigated with multiple correspondence analysis and multiple regression modeling. We found that triticale and oat were more related to isolates classified into F. graminearum s. lato than with other isolates. In contrast, wheat and rye were more associated with F. graminearum s. stricto. Cereal crop species affected the frequencies of F. graminearum s. stricto (p = 0.003) and F. graminearum s. lato (p = 0.08) and unidentified isolates with morphological characteristics like those of FGSC members (p = 0.02). The effectiveness of species-specific primers was 60.3% (Fg16F/R) and 76.2% (FgrF/FgcR), and the effectiveness of primer sets for the trichothecene genotyping of the Tri5 and Tri3 genes was 100% and 90.6%, respectively. The decrease in Fusarium-damaged kernel values in the wheat–pea intercropping system indicated that intercropping systems have the potential to control FHB.

Pea–cereal intercropping may combine ecological disease regulation with improved land-use efficiency, but field evidence for pea powdery mildew responses on the pea component under temperate continental conditions remains limited. A two-year field experiment (2017/2018 and 2018/2019) was conducted in Novi Sad, Serbia, to evaluate the effects of intercropping on pea powdery mildew disease index (DI%), pea grain yield, seed physical quality traits, and land-use efficiency. Winter pea cv. Kosmaj was grown as a sole crop or in mixed intercropping (70% pea + 30% cereal seeding rates) with wheat, triticale, rye, or oat in a randomized complete block design with four replicates. Powdery mildew DI% was assessed at BBCH 71–75, while pea grain yield, thousand-seed weight (TSW), hectoliter weight (HLW), and yield-based land equivalent ratio (LER) were determined at harvest. Under the low natural disease pressure recorded in the study, intercropping was associated with lower DI% than sole cropping (approximately 2.8-fold lower on seasonal means; p < 0.001), but DI% did not show a significant independent effect on pea grain yield, TSW, or HLW after accounting for year and cultivation system. Pea grain yield was generally lower under intercropping, although the magnitude of reduction depended on the cereal companion; pea–triticale maintained pea yield closest to the sole crop, whereas pea–oat showed the lowest pea yield. TSW and HLW were generally higher under intercropping, but additional analyses indicated that these traits reflected different response patterns. All intercrops achieved LER > 1, with the highest values recorded for pea–triticale.

The harvest index of grain can be used as indicator for the potential yield of crop. The aim of this study was to determine the variation of the harvest index for wheat and triticale and differences in monocrops and intercrops systems of cultivation under different field environmental conditions. The experiment, carried out in field conditions for two consecutive years, was designed according to a randomized block system so that each species was sown in two cultivation systems as a single crop and a combined crop (wheat + pea and triticale + pea) in four replicates. The results show that, in the first year of the experiment, the value of the harvest index varied from 32.5% (triticale + pea) to 39.3% (wheat monocrop), while in the second year of the research, the value of the harvest index varied from 26.4% (wheat + pea) and 28.1% (triticale + pea). As for the components of harvest index, values of weight of grains spike-1 and weight of total above ground biomass were higher in intercrops than in monocrops system of cultivation. It can be concluded that the intercropping of cereals (triticale and wheat) and forage crops (pea) provided positive effects on weight of grains spike-1 and weight of total above ground biomass and does not diminish harvest index when compared to standard system of cultivation.