Journal on Processing and Energy in Agriculture 18 (2014) 4 175 Biblid: 1821-4487 (2014) 18; 4; p 175-178 Original Scientific Paper UDK: 634.25: 582.923.6 Originalni naučni rad THE DOMINANT WEED SPECIES IN ORGANICALLY FARMED PEACH - PRUNUS PERSICA BATSCH. (ROSACEAE A. L. DE JUSSIEU 1789, ROSALES) DOMINANTNI KOROVI PRI ORGANSKOJ PROIZVODNJI BRESKVE - PRUNUS PERSICA BATSCH. (ROSACEAE A. L. DE JUSSIEU 1789, ROSALES) Dejana DŽIGURSKI, Branka LJEVNAIĆ-MAŠIĆ, Ljiljana NIKOLIĆ University of Novi Sad, Faculty of Agriculture, Trg Dositej Obradovića 8, 21000 Novi Sad, Serbia e-mail: dejana@polj.uns.ac.rs ABSTRACT Floristic study of weed vegetation in a peach orchard in Bajmok, certified for organic production, revealed the following pre- dominant species: Erigeron canadensis, Cirsium arvense, Convolvulus arvensis, Chenopodium album, Polygonum lapathifolium, Sorghum halepense, Solanum nigrum, Sinapis arvensis, Setaria viridis, Rubus caesius, Sonchus arvensis, Artemisia vulgaris and Capsella bursa-pastoris. Based on the taxonomic analysis findings, the weed families Asteraceae (4 species), Poaceae (2 species) and Brassicaceae (2 species) comprise the greatest number plant species. Among the analyzed weed species, most of which bloom from June to September, 84.62% are weed-ruderal, and the remaining 15.38% are classified as ruderal. The weed flora life-form spectrum reveals therophyte dominance (53.85%): T 4 (38.46%), T 1 (7.69%) and T 3 (7.69%). Geophytes contribute by 30.77%, or 4 taxa, namely G 3 (23.08%) and G 1 (7.69%). Finally, hemicryptophytes are present with 15.38%: H 3 (7.69%) and H 5 (7.69%). Based on the ecological weed flora analyses, the habitat is meso-eutrophic (N – 3.77), unsalinated (S - - 84.62%), and favorably aerated (D – 3.85), and is characterized by moderate humidity (F – 2.54), neutral reaction (R – 3.15), and moderate humus content (H – 3.00), as well as favorable light (L – 3.77) and thermal (T – 3.92) regimen. Phytogeographical analysis of the weed flora in the aforementioned peach orchard indicates the dominance of widely distributed taxa (92.3%)—a characteristic of weed vegetation. Key words: Prunus persica, organic production, weeds, ecological analysis. REZIME Korovi u voćnjacima nanose voćarskoj proizvodnji ogromne štete. Njihova prisutnost iznad praga štetnosti značajno smanjuje rod i narušava kvalitet plodova. U organskoj proizvodnji voća cilj nije, kao u konvencionalnoj, uništiti korove, već ih treba dovesti u ravnotežu sa voćarskom kulturom. Florističkim istraživanjem korovske vegetacije u zasadu breskve u Bajmoku, na gazdinstvu regis- trovanom za organsku proizvodnju, veće vrednosti brojnosti i pokrovnosti imaju vrste: Erigeron canadensis, Cirsium arvense, Convolvulus arvensis, Chenopodium album, Polygonum lapathifolium, Sorghum halepense, Solanum nigrum, Sinapis arvensis, Se- taria viridis, Rubus caesius, Sonchus arvensis, Artemisia vulgaris i Capsella bursa-pastoris. Taksonomska analiza ukazuje da su biljnim vrstama najbrojnije familije Asteraceae, Poaceae i Brassicaceae. Od analiziranih taksona zastupljene su korovsko-ruderalne (84,62%) i ruderalne (15,38%) biljke. Spektar životnih formi flore ukazuje na dominaciju terofita (53,85%). Među njima najbrojnije su T 4 (38,46%) terofite, a znatno manje zastupljene su T 1 (7,69%) i T 3 (7,69%) terofite. Geofite su prisutne sa 30,77% i to G 3 (23,08%) i G 1 (7,69%). Hemikriptofite su zastupljene sa 15,38% i to H 3 i H 5 sa po 7,69%. Ekološka analiza korovske flore ukazuje da je stanište umerene vlažnosti (F – 2,54), neutralne reakcije (R - 3,15), mezo-eutrofno (N - 3,77), srednjeg sadržaja humusa (H - 3,00) i povoljne aerisanosti (D - 3,85), nezaslanjeno, povoljnog svetlosnog (L - 3,77) i termičkog (T - 3,92) režima. Rezultati analize flore korova: ekološka, taksonomska, biljnogeografska, analiza vremena cvetanja i kategorizacija prema staništu, doprinose sagledavanju raznovrsnih odnosa u istraživanom agroekosistemu radi uspostavljanja samoregulatornih procesa i podsticanju biodiverziteta. Ključne reči: Prunus persica, organska proizvodnja, korovi, ekološka analiza. INTRODUCTION In contrast to conventional systems, organic fruit production is based on the use of natural resources (organic and natural fer- tilizers and plant protection measures), capitalizing on the ge- netic potential of varieties and continuous production control (Mratinić, 2005). Thus, when making a transition from the con- ventional to organic production, the conversion period must be respected — typically 36 months before fruit harvesting. Worldwide, organic production of continental fruit varieties is currently conducted on 250,000 ha, with Italy, USA, France, Spain, Poland and Germany as the most important producers (Granatstein et al., 2013). In Serbia, in 2012, 5,145.19 ha was dedicated to organic fruit production, of which 4,054 ha already had organic status and 1,091.19 ha was in the conversion period. Currently, orchards occupy 46.7% of the total land area under organic production (Organska poljoprivreda u Srbiji 2013). Unfortunately, in 2013, organic fruit production was con- ducted on only 1,884 ha, of which 1,527 ha had organic status, and 357 ha was in the conversion period (Organska poljo- privreda u Srbiji 2014). Peach (Prunus persica Batsch., syn. Persica) is a member of subfamily: Amygdaloideae, family: Rosaceae; order: Rosales; superorder: Rosanae; subclass: Rosidae; class: Magnoliopsida (Takhtajan, 2009). It has been grown for 4,000 years. At the be- ginning of the new era, it arrived from Persia to Greece, and sub- sequently spread across many other regions. Peach thrives in warmer climate, and is thus most abundant in the temperate zone of the northern and southern hemispheres. In Serbia, it is grown on light and fertile soil with pH 6.5-7.5. While peach can sustain only brief periods of colder temperatures (up to -30 ° C), its de- velopment and growth is unaffected by excessive heath (Gvoz- denović et al., 1997). In orchards, weed can cause significant damage to fruit pro- duction. Presence of weeds in orchards above the damage