Climate change projections for the 21st century pose great threats to semi-arid regions, impacting seed production and the quality of sunflowers. Crop yields are negatively affected by climate variability, especially in the event of droughts during the crucial growth stages. Understanding the relationships between agrometeorological, genetic, and agronomic factors is crucial for maintaining crop sustainability. Optimal sowing dates are an essential condition for maximizing crop genetic potential, but challenges come from annual weather variations. This study analyzes how sunflower genotypes respond to different sowing dates under climate change and focuses on the conditions for obtaining maximum seed yields and favorable agronomic traits. From 2020 to 2022, the experiment featured six genotypes sown across four different dates at two-week intervals, simulating seed sunflower production. The results obtained by ANOVA indicated that the seed yield and oil yield were significantly affected by the sowing date, the genotype, and their interaction, with coefficients of variation ranging from 7.6% for oil yield to 41.1% for seed yield. Besides seed yield and oil yield, LDA biplot and Discriminant Functions confirmed that seed germination energy also played a significant role in separating genotypes into clusters. A Visual Mixed Model showed that shifting the optimal sowing date (mid-April) to early May allows a reduction in the number of days the plants spend in critical growth stages, thereby escaping stressful conditions during pollination and seed filling. The findings resulted, on average, in increased yields and improved seed quality, which are the primary goals of seed production, but not in increased 1000-seed weight. Notably, high temperatures during the critical sunflower growth stages negatively affected the measured parameters of seed production. The increased precipitation during seed filling boosted the 1000-seed mass and seed yield. Extended flowering reduced the growth rate and seed germination, but longer seed filling increased the 1000-seed mass and seed yield. Our future breeding goals will be to create genotypes with a shorter flowering period and an extended seed-filling period to better respond to climate change.

Five different rapeseed genotypes were tested. The following traits were considered: seed yield, seed germination, seed oil content, 1000 seed weight and seed protein content and they were used to determine whether there is significant or nonsignificant correlation. Highest average results were determined in genotype G-3 (yield 2.544 kg; germination 90%; 1000 seed weight 4,30 g; oil content 45,31% and protein content 19,83%) while G-5 (1.838 kg; 87%; 3,50 g; 44,77% and 17,28%) had the lowest average result of observed parameters. Highly significant positive correlations were found while comparing seed yield with 1000 seed weight (0.753**) and protein content (0.726**). High significant positive correlation were also determined comparing seed germination with 1000 seed weight (0.832**) and protein content (0.892**). Also high significant correlation was determined comparing 1000 seed weight and protein content (0.812**). Positive significant correlations were found by comparing seed yield and seed germination (0.644*). Path analysis indicated highest significant positive direct effect of 1000 seed weight (0.716**) and protein content (0.666**) on seed yield. High but negative significant value had seed germination (-0.645**). In the study of indirect effects on seed yield, none of significant effects were determined. The study of direct effects on oil content showed that the seed germination had high significant positive effect (-1.296**) on oil content. Significant but hot high effect has seed yield (0.556*). In other two traits it was determined negative high significant effects (1000 seed weight - 0.797** and protein content - 0.717**) on seed oil content. The existence of indirect significant effects on oil content in four cases was determined.

The main focus of industrial sunflower processing is oil production, in which the pericarp is most often treated as a byproduct or biological waste. However, sunflower pericarps have shown significant potential for alternative applications. Bridging the gaps in knowledge of the properties of achenes and their byproducts would improve the efficiency of industrial processes and open new possibilities for utilizing the pericarp as a biological resource. In this work, we analyzed biophysical and morphometric properties of the achenes of eight sunflower genotypes. Their byproducts indicate a complex interrelationship among the analyzed traits. The basic achene color of the tested genotypes was gray, with dark to light shades. Larger achenes had larger seeds and a higher weight, while more spherical achenes had a higher proportion of pericarp. Additionally, achenes with a smaller cavity between the seed and the pericarp had a higher germination percentage. Genotypes with a thinner and softer pericarp had higher oil content, while greater thickness contributed to its reduction. Pericarp hardness was proportional to the number of sclerenchyma layers, not to the percentage of sclerenchyma. These findings suggest that pericarp structure can be a key determinant for both oil yield and byproduct valorization, enabling the selection of genotypes for specific industrial applications.

Summary: As plant breeding is a very complex and sophisticated process, it is of paramount importance to understand the nature and magnitude of interdependence between specific plant features. Using PCA and correlation analysis, this study examined the variability in features of two types of inbred sunflower lines and determined its connection with their seed yields. The experiment was conducted as a randomized complete block design with four replications in Rimski Šančevi (the experimental field of the Institute of Field and Vegetable Crops in Novi Sad) in 2018 and 2019. It examined a total of nine inbred sunflower lines created at the Institute of Field and Vegetable Crops in Novi Sad. The results obtained suggest a high degree of variability in the examined traits of inbred sunflower lines considered, whereas the significance indicated by the F test was confirmed by the Duncan test performed. A high degree of variability was also found between the different types of inbred lines considered. A positive correlation was found between all four traits observed in the inbred sunflower lines considered, with different levels of significance. A statistically significant positive increase in the head diameter was followed by an increase in the weight of 1000 seeds, which generated a higher seed yield per unit area. According to the arrangement of different types of inbred lines considered on the PCA biplot, it can be concluded that the linoleic inbred lines G7 ^L and G8 ^L had the highest average values of the 1000-seed weight, head diameter and seed yield throughout the course of both experimental years. The useful data obtained by PCA analysis can facilitate successful selection programs aimed at developing sunflower genotypes that possess high stability and seed yields.

Climate changes inevitably affect plant production, but it is difficult to predict their direct impact on a vitality (germination) of a produced seed. Germination is the most important indicator of seed vitality and a key stage in the life cycle of plants. Seed germination is significantly affected by environmental factors during the growing season, as well as the method of processing (according to seed size). The aim of this work was to determine the impact of three factors on seed germination of four sunflower inbred lines: i) genotype, ii) environment conditions in a production year, and iii) seed size obtained during processing. The germination was examined in a standard laboratory test by ISTA Ruls, six months after the processing and natural breaking of dormancy. Larger and smaller sizes seeds, obtained in two consecutive years, which were characterized by different environmental conditions (sum of precipitation, mean monthly temperatures and air humidity during flowering), were used. Collected data was analyzed using a three-way analysis of variance, and correlation analysis. The coefficient of variation was 8.19%. Significantly higher average seed germination was obtained during 2020 (92%,) compared to 2021 (85%). The effect of seed size was not statistically significant, regardless of the tested inbred line. It can be concluded that the increase in the seed germination of sunflower inbred lines is mainly influenced by genotype, but also the increase in precipitation, minimum and maximum air humidity during flowering and the decrease in mean monthly temperatures, which was confirmed by the correlation coefficients between the above agroecological conditions and the germination rate of the produced seeds.

The sunflower is a significant oil crop that can thrive in various environmental conditions. However, due to the changing climate, the pathogen profile has been altered, posing a threat to sunflower production. Among the various threats, charcoal rot, caused by the soil-borne fungus Macrophomina phaseolina (Tassi) Goid, is one of the most significant. This study aimed to assess the resistance of 79 sunflower inbred lines to this pathogen using two inoculation methods (toothpick method and unwounded stem base inoculation) and natural disease occurrence in field trials spanning two years. The results showed that both inoculation methods and natural disease occurrence effectively differentiated between resistant and susceptible inbred lines, with the toothpick method being the most effective. Thirteen inbred lines were resistant, 16 were susceptible, and the others were moderately resistant or susceptible. The study identified four inbred lines (MA SC 2, L 1, Ha 74, and PB 21) as the most resistant, making them important sources for breeding sunflower hybrids resistant to M. phaseolina. Their resistance was confirmed in the second year, highlighting their potential to combat the impact of climate change on sunflower production. This study represents a valuable insight into the biological control of M. phaseolina using sunflower resistant genotypes, especially since resistance findings have been lacking in other plant species.