The ongoing climate change, coupled with the transformations of cultivation practices and land use in sole crop production, may cause a significant decline in sunflower yield stability. Considering that the sunflower is the third oilseed in the world oilseed market, with 45 million tons of grain per year, and that it takes the fourth position in the vegetable oil market, the implementation of sustainable growing technology in sunflower production is a necessity. Considering the above, the goal of the research was to analyze and recommend sustainable sunflower production technology in intercropping systems. A four-year trial was conducted in Serbia’s agroecological conditions (45∘34′23.2′′ N 19∘86′18.9′′ E) using a split-plot design. Two oil-type hybrids and one confectionary-type hybrid were intercropped with common vetch, red clover, and alfalfa. Common vetch × sunflower intercropping resulted in the decrease in almost all sunflower traits. Moreover, sunflower × alfalfa intercropping proved to be the most appropriate. The yield of NS Gricko and Rimi PR were statistically on the same level with sole cropping, while alfalfa biomass had better results after alfalfa was intercropped with NS Gricko, as compared to sole cropping. In view of the prevailing belief that yields are more stable in intercropping than in sole cropping, further research is needed in this respect, in addition to further research of the time and method of sowing.

Given that climate change is a burning issue, agriculture must turn to more sustainable and environmentally friendly systems, counting intercropping. Within a two-year study of intercropping sunflower with legumes, the influence of this system on sunflower plant height and head diameter was investigated. The aim of research was to evaluate the effects of sunflower-legume intercropping on these traits, considering the possibility of competition between crops. The field trial was set up in April 2017 and 2018 at Institute of Field and Vegetable Crops, Novi Sad, Republic of Serbia experimental field in moderate-continental climate. Year 2017 was extremely arid with the sum of precipitation different compared to 2018. Plant height and head diameter of hybrids Rimi PR, Dukat and NS Gricko, intercropped with common vetch, red clover and alfalfa were compared with control, i.e. same sunflower hybrids grown as a sole crop. It was observed that intense growth of common vetch suppressed the growth of sunflower, and led to a decrease in measured traits in all three hybrids. Results indicated that the following combinations of sunflower and legumes are most desirable: NS Gricko/RC, Dukat/ALF, Dukat/RC and Rimi PR/ RC depending on the agro-ecological conditions. Given that the experiment was performed in years that varied significantly in agro-ecological conditions, the results indicated that red clover and alfalfa can mitigate the negative effects caused by lack of precipitation and high temperatures. In order to better understand all aspects of sunflowerlegume intercropping, further research, which should include other morphological, qualitative and quantitative indicators, is needed.

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 G7L and G8L 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.

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As organic agriculture represents one of the most sustainable ways of agricultural land use, the key purpose of this research was to improve confectionary sunflower production in organic agriculture. The trial compared seed yield per plant of conventional confectionary sunflower hybrids in organic vs conventional production. Subsequently, 1000 seed weight, seed yield per plant and kernel ratio of confectionary hybrids treated with the following fertilizers used in organic production: fertilizer of animal origin (G), fertilizer based on amino acids and nitrogen (T) and microbiological fertilizer (N) were compared with untreated control (C). Fertilizers enhanced yield of sunflower compared to untreated control; the highest yield was recorded in combined of G+N and G+T, all in organic agriculture system. NS Gricko had the lowest seed yield per plant compared to the other hybrids that significantly increased when treated with G+N fertilizers; same results were obtained in treatments of NS Slatki, and NS Leviathan. Preliminary results of the study indicated that application of organic fertilizers can have a positive effect on yield of sunflower in organic production conditions, which indicates that further research is necessary.

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Except agronomic important traits, great diversity in sunflower is present in morphological traits which are very useful in breeding studies. The main objective of the paper was to determine genetic diversity among the 110 inbred lines in the collection of Institute of Field and Vegetable Crops Novi Sad (IFVCNS) by screening 34 morphological traits according to a list of descriptors of the International Union for the Protection of New Varieties of Plants (UPOV) as to conduct the Distinctness, Uniformity and Stability Test (DUS). The diversity of morphological traits was estimated by Shannon diversity index (H?) and the diversity of sunflower inbred lines was performed by homogeneity analysis (HOMALS) as well as discriminatory power of the traits. The values of the traits in Shannon diversity index were the highest (H?=0.99) for height of the tip of the blade compared to insertion of petiole and bract position, while branching, head shape and seed color showed low diversity (H?>0.1). The uniformity of inbred lines distribution determined discriminative power of descriptors. Disk flower anthocyanin coloration of stigma, hypocotyl anthocyanin coloration and intensity, leaf blistering, leaf serration, seed stripes on and between the margins showed the strongest discriminatory power. According to these six traits, the collection of inbred lines was divided into two main groups and three subgroups which better explained the relationships among the various inbred lines. Inbred lines showed the great variability of morphological traits in the whole collection and also among the inbred lines from the same type of use.

The aim of this research was to determine the optimum planting density for the production of high-quality cut flowers with desirable characteristics. 25 single-stem ornamental sunflower genotypes were planted at different densities and evaluated for flowering time, flower diameter, and stem circumference and length over a two-year production cycle. Three spacing patterns were used: 25 × 25 cm, 30 × 30 cm, and 70 × 30 cm, which led to the planting densities of 160 000, 90 000, and 60 000 plants/ha, respectively. The plant density had the most important effect on the stem circumference, flower diameter, and stem length (total variation 52, 60, and 58%, AMMI analysis) and a small effect on the flowering time (total variation 1%, AMMI analysis). Based on environment-focused scaling, all high-density environments could be suitable for the production of single-stem sunflower genotypes. The results demonstrated the adaptation of several sunflower genotypes G9, G11, G12, G21, and G22 as the most suitable based on the optimum flower diameter, stem circumference, and stem length. These results may lead to progress in growing ornamental sunflowers as a cut flower.