This study aims to do a morphological and biochemical characterization of selected wild hop populations from the Banja Luka region, as plant material with potential value for introduction into plant selection. Female inflorescences (cones) from seven populations (DKH3, DKH5, DKH6, DKH8, DKH9, DKH10, and DKH11) were sampled in 2018 and 2019. Hop cones were collected in October 2018 and 2019 for morphological characterization, when 50 cones per population were analyzed, and also the cones were collected in mid-September in 2019 for biochemical characterization. Morphological parameters were carried out for: cone length (cm), number of nodes per cone spindle, cone density, and number of seeds per cone, all important agronomic characters in hop production. Also, 27 components of essential oil and 6 components of hop resins were analyzed. Statistical analysis of morphological characteristics was performed by factorial analysis of variance (year × population), and the significance of individual differences was determined by LSD test. The grouping of examined hop populations according to the manifested morphological characteristics was performed by cluster analysis. Statistical analysis for biochemical characteristics was performed by analysis of variance, and the significance of the differences was tested by Tukey’s statistical test. In order to determine similarities between different population multivariant statistical method Principal component analysis (PCA) was applied. According to morphological and biochemical analysis, DKH6 hop population is singled out as the most valuable for hop breeding.

The objective of the paper was to determine the effect of insecticides on the development of the European corn borer (Ostinia nubilalis Hbn) and the effect of damage in six maize hybrids of different maturity groups. The research involved the following hybrids: ZP 427, ZP 434, ZP 555, ZP 600, ZP 606 and ZP 666. In the field trial, insecticides were applied in two terms, during the flight of O. nubilalis first generation and during the flight of second O. nubilalis generation. We used Fobos EC insecticide and a combination of Match 050 EC + Nurelle D insecticides, whose active substances are different. The active substance in Fobos EC insecticide is bifenthrin 100 g l-1, in Match 050 EC lufenuron 50 g l-1 and, in Nurelle D insecticide, the active ingredient is a combination of chlorpyrifos 500 g l-1 and cypermethrin 50 g l-1. The damage inflicted on plants was assessed in July and September. Fobos insecticide had the best plant protection effect, after its use, the arithmetic mean of the total attack percentage of all hybrids was approximately 81.62% while in the control group, it was approximately 91.72%.

Advantages or disadvantages of intercropping system can estimate through expression of components of yield on the base of values of productive organs (spike, pod). The aim of this work was study of variation of spike index in cereals species and pods index in pea of spring intercropping. For investigation included spring species of small grains: wheat, triticale, oat and spring legume pea. The investigation was carried out in field condition in experiment with randomised block design of 5m2 plots, with 4 replications. Each species (cereals and pea) were sown sole and in intercrops wheat+pea, triticale+pea and oat+pea. At the maturity stage used 40 plants (10 plants/replication) for determining harvest index of spike in cereal species and index of pea pods on the base of analysis of spike mass and pod mass and seed mass spike-1 and seed mass pod-1 . Seed mass spike-1 of small grains species genotypes variate in ratio of 0.85 g (wheat+pea) and 1.59 g (oat intercrops) with average 1.19 g for all crops of cereals and variant of cultivation. The spike mass variate in range of 1.37 g (triticale intercrop) and 2.23 g (wheat intercrops) with average 1.72 g for all cereals and variant of cultivation. Harvest index of spike variate between 62.5% (triticale sole) and 89.2% (oat sole). The value of spike mass was the higher in wheat intercrops than in wheat sole, while for triticale and oat spike mass is lower in intercrops. In the same of analyzed small grain species, seed mass was the higher in sole crops than in mixture with pea. The spike index, only in intercrop triticale+pea (63.2%) was slightly higher than in single crop of triticale (62.5%). Pod mass and seed mass pod-1 of pea was the higher in pea intercrops than in pea sole. The highest pod mass was in intercrop pea+triticale (0.72 g) and the least in single crop of pea (0.45 g) with average 0.62 g for all crops. The highest seed mass pod-1 was the highest intercrop pea+triticale (0.56g) and the least in monocrop of pea (0.32 g) with average 0.46 g for all crops. Harvest index of pod variate in ratio 68.0% (pea single) and 77.% in pea/triticale intercrop. Pod index of pea in mixture with each small grains species genotypes was higher than in pea's monocrop. On the base of result we can conclude that intercropping cereals + pea, have positive effect on spike and pod characteristics which values were higher in majority of studied intercrops than in monocrops.

The aim of this study was to analyze the spike length, number of grains per spike and grain weight per spike of winter wheat in agro–ecological conditions of Banja Luka at different sowing densities. Three winter wheat varieties (NS 40S, Prima and Nova Bosanka) were examined at seven sowing densities (384, 424, 451, 504, 544, 588 and 604 seeds/m2) in two growing seasons (2013/14 and 2014/15). Experimental design was a completely random system with four replications. In all wheat varieties, sowing was carried out from the 6th to 8th November in 2013/14 and from the 3rd to 5th November in 2014/15. Sampling of plants was done in the first decade of July in both experimental years. Factorial ANOVA 2×8×3 and LSD‒test were performed, with year, sowing density and variety as main factors. For different varieties, the average number of grains per spike ranged from 34.53 to 38.19 while the average grain weight per spike (g) ranged from 1.58 to 1.73 g. The spike length ranged from 7.58 to 8.20 cm for varieties with statistically significant interaction effect variety × year at P ≤ 0.01. Spike parameters were generally higher in the second experimental year (2014/15).

Ostrinia nubilalis Hbn. is a corn pest that can do great damage to plants in some seasons. The aim of this paper is to study the resistance / susceptibility of hybrids to the attack of European corn borer and the effects of different doses of insecticides and time of application in protection against pests on maize plants, but primarily the influence of hybrids on attack intensity. The six maize hybrids of different maturation groups (ZP 427, ZP 434, ZP 555, ZP 600, ZP 606 and ZP 666) used for study effect of attack of Ostrinia nubillalis Hbn., on control variant T1 without application of insecticide and on variant treated with two insecticides Fobos EC (bifentrin - 200 ml ha-1) and combination of Match 050 EC and Nurelle D (lufenuron 50 g l-1 and hlorpirifos 500 g l-1 + cipermetrin 50 g l-1), 0.75 l ha-1) in two terms (in the first generation of insect flying T2 and T3 and in the second generation of insect flying T4 and T5) in three replication. The results showed the highest intensity of Ostrinia nubilalis Hbn. attack and degree of damages on control variant and significant differences between treatments for investigated parameters. Observing all hybrids and treatments, there was no statistical significance between the six examined maize hybrids of different maturity groups. In the control variant, the greatest attack (damage) was in plants, namely in the hybrid ZP 666 (94.28%) and ZP 606 (93.90%) and among the variants of applied insecticides, the greatest damage was found in the treatment T5 with the applied combination of Match + Nurelle in hybrid ZP 555 and was 92.02%. On treatment T1-control variant without insecticides, the smallest attack with Ostrinia nubilalis Hbn. was found in the hybrid ZP 434 (from 88.76%) and among the variants of applied insecticides, the smallest attack was found on variant T2 with applied Phobos in the first generation of insect in hybrid ZP 434 and amounted to 77.12%. The attack of Ostrinia nubilalis Hbn. and variation of average mass of maize cob varied in dependence of maze of hybrids and variant of insecticides application.

Wheat yields in production often fall below the genetic potential of varieties, creating a persistent challenge in improving productivity. This study investigated the effects of genotype, sowing date, sowing density, and fertilization model on wheat yield, as well as their interactions, to identify optimal management strategies. Field trials were conducted during two successive growing seasons in the Semberija region, Republic of Srpska, Bosnia and Herzegovina, using three wheat varieties. The experiment followed a randomized split-plot design with three replications, including three varieties, three sowing dates, five sowing densities, and three fertilization models. Data were analyzed with four-factor ANOVA, and significant differences were tested using Fisher’s LSD at the 0.05 and 0.01 probability levels. The results showed that average yields exceeded 8,000 kg ha⁻¹ in the first year, but decreased with delayed sowing. Yield losses due to late sowing could not be offset by increasing seed density, although 400-500 seeds m⁻² proved optimal. Fertilization effects varied across conditions, with the second fertilization model producing the highest yields under favorable circumstances. Overall, both individual treatments and their interactions significantly affected yield, underscoring the importance of tailoring sowing and fertilization practices to specific varieties and environments.