Brassica oleracea varieties (red cabbage, broccoli, Savoy cabbage and cauliflower) were tested for their ability to regenerate shoots in vitro. Cotyledon, hypocotyl and root explants of 7 day-old seedlings were incubated on Murashige and Skoog's (MS) medium supplemented with 1 mg l-1 6-benzyladenine (BA) or 6-furfurylaminopurine (KIN) in combination with 0, 0.1, and 0.2 mg l-1 indole-3-butyric acid (IBA). Hypocotyls showed the best explants in almost all varieties tested with a minimum regeneration potential of 75% and producing 3.5-7.4 shoots per explant. The BA-supplemented media were optimal for both shoot regeneration and multiplication. Shoots rooted maximally (100%) on plant growth regulator-free MS medium containing 2% or 4% sucrose. Increased sucrose content improved plant acclimation in the greenhouse

A study was carried out during the 2005 and 2006 growing seasons to evaluate the effect of increasing nitrogen fertilization rates on nitrate accumulation, vitamin C and ß-carotene content in two carrot genotypes. Nitrogen fertilizer (calcium ammonium nitrate, 27% N) was applied at four rates: 0, 60, 120 and 180 kgNha-1. After harvesting, root samples were collected and tested for quality. The use of increasing nitrogen rates resulted in increased nitrate accumulation in the roots. The increase in nitrogen fertilizer rate from 60 to 120 kgNha-1 led to a reduction in Vitamin C content and an increase in ß-carotene. Differences were observed between cultivars and hybrids in all quality parameters tested.

In order to investigate the variability of bulb yield, the trial was set up on an experimental plot of the Centre for Vegetable Crops in Smederevska Palanka during 1997 and 1998. The trial was performed by applying the method of random block system in five replications. Ten varieties of different geographical origins were included as the research material. The recorded values of the investigated features were determined by applying the variance analysis of a two-factorial trial model 2 (Hadživuković, 1991). The components of the phenotype variance, genotype and phenotype coefficient of variation and heritability in broad sense were estimated according to Singh and Chaudhary (1976). Significant variability was recorded for yield bulbs in both years of investigation. For this parameter, genotype variance was greater than the enviromental. Phenotype coefficient of variation (PCV) was greater than genotype coefficient of variation (GCV). Heritability confirmed that the genotype variability was stronger in the overall phenotype variability

In order to estimate, at the molecular level, the divergence of parental lines that were used in diallel crossbreeding for production of superior offspring (F1 generation hybrids) at the Institute for Vegetable Crops, the molecular analysis using five RAPD markers for five pairs of parents has been performed. It gives an insight into their genetic polymorphism and the possibility of their further use in breeding programs. Information from this research has pioneered the application of molecular markers of onion in Serbia. Analyses were performed using the RAPD primers, which in previous studies established a high degree of polymorphism. In all five cases there was a corresponding amplification of DNA segments. From totally 50 bands analyzed, the length of fragments ranged from 500 to 3000 bp. Number of polymorphic band per example was 8 to 13. In our research at the level of the analyzed primers, a high degree of polymorphism between analyzed genotypes has been found. Based on UPGMA dendogram, analyzed genotypes were divided into two main clusters and two subclusters

Extracts were subjected to the following analyses: determination of total phenols, total flavonoids and anthocyanins, and refractometric determination of soluble solids. The results showed that the content of flavonoids was 0.4710 mg/ml in Urtica dioicа extract, 0.3950 mg/ml in Equisetum arvense extract, 0.2997 mg/ml in Thymus serpyllum extract and 0.1556 mg/ml in Achillea millefolium extract. The highest content of phenolic compounds was found in Thymus serpyllum extract (2.3583 mg/ml), followed by Equisetum arvense (2.2724 mg/ml) and Urtica dioicа extract (2.1374 mg/ml), and the lowest in Achillea millefolium (1.8061 mg/ml). The content of anthocyanins was highest in Urtica dioicа extract (3.966mg/l), followed by Thymus serpyllum (3.715mg/l) and Equisetum arvense (3.549mg/l) extracts, and lowest in Achillea millefolium extract (0.0835mg/l). The soluble solids content was highest in Urtica dioicа and Equisetum arvense (2 BRIX% at 20 o C), followed by Thymus serpyllum (1.5 BRIX% at 20 o C), and lowest in Achillea millefolium (1 BRIX% at 20 o C). The results showed that extracts obtained by maceration contained bioactive components; this study, therefore, provides a basis for further and deeper research on the use of these extracts as potential biostimulators in organic agriculture.