Primena metoda multivarijantne analize u proučavanju korovske vegetacije na primeru severozapadnog Balkana

Studies of weed vegetation by using Braun-Blanquet's method have been traditional in the north-western Balkans but only studies based on synoptic tables of weed vegetation have so far been conducted in the area of the former Yugoslavia (Kojić, 1975). Over the past two years, all available relevés of weed vegetation (4258) in the area have been collected in a database, which we have analysed using the latest methods of multivariate analysis in different statistical softwares, such as JUICE, CANOCO, PC-ORD, etc. The results of classification, indirect and direct ordination and application of indicator values (Pignatti, Raunkier forms) in the analysis of weed vegetation are shown on examples from the former Yugoslavia, and will be compared to results acquired under the conventional approach of Braun-Blanquet's scool. It will show the advantages of the new approach in studies and interpretation of weed or any other type of vegetation.Korovska vegetacija u Evropi je najviše proučena klasičnim florističko-fitocenološkim metodama i to uglavnom na regionalnom nivou. Međutim, poslednjih desetak godina sve više se upotrebljavaju veći setovi podataka (velika područja), koji su donekle uticali na drugačiji pristup tumačenju faktora koji utiču na floristički sastav i diferenciranost korovske vegetacije. U vezi s tim, analiza i interpretacija korovske vegetacije primenom multivarijacionih metoda je postala pravi trend u ovakvoj vrsti istraživanja. Proučavanje korovske vegetacije Braun-Blanquetovom metodom ima bogatu tradiciju na tlu severozapadnog Balkana, ali do sada su uglavnom rađene samo studije iz pojedinih područja kao sinoptičke tablice pregleda korovske vegetacije za područje bivše Jugoslavije (Kojić, 1975). U zadnje dve godine u bazi podataka sakupljeni su svi dostupni vegetacijski snimci (4258 sastojina) korovske vegetacije sa tog području, koje smo analizirali koristeći najsavremenije metode multivarijantne analize u različitim statističkim programima kao što su JUICE, CANOCO, PC-ORD itd. Na praktičnim primerima u radu će biti prikazani rezultati klasifikacije, indirektne i direktne ordinacije i primene indikacionih vrednosti (Pignatti, Raunkierovi oblici) u analizi korovske vegetacije razvijene na prostorima bivše Jugoslavije i kao takvi biće upoređeni sa rezultatima pregleda korovske vegetacije rađene klasičnim principima Braun-Blanquetove škole. Dakle, dobiće se uvid u prednosti novog pristupa u proučavanju i interpretaciji korovske, odnosno bilo koje druge vegetacije. Multivarijantne metode omogućavaju dobijanje informacija iz više-dimenzionalnog sveta, kao što je priroda, a naročito dinamična korovska vegetacija, a koje nisu direktno vidljive. Klasifikacija korovskih/ biljnih zajednica ovim sistemom omogućava objektivnije grupisanje velikog broja podataka, za razliku od starih principa Braun-Blanquetove škole gde je to rađeno intuitivno, tj. na osnovu iskustava istraživača. Ordinacionim tehnikama mogu se koristiti i merljivi parametri kao što su tip useva, godina, sezona, nadmorska visina itd., a primenom parcijalnih ordinacija uticaj pojedinih varijabli i nivo njihove statističke značajnosti u razvoju određenog tipa vegetacije

Vilina kosica - životni ciklus i interakcija sa domaćinom

Field dodder is a parasitic plant that attaches to stems and leaves of broadleaf plants, including weeds, field crops, vegetables and ornamentals, across most agricultural regions of the world. Effective field dodder control is extremely difficult to achieve due to the nature of attachment and close association between the host and the parasite, which require a highly effective and selective herbicide to destroy the parasite without damaging its host. To establish a strategy for controlling parasite growth and restricting the spread of field dodder in crop fields, it is important to learn more about this weed, its life cycle and development.Vilina kosica je parazitska cvetnica koja se vezuje za stablo i lišće biljaka domaćina i parazitira značajan broj ekonomski značajnih vrsta, korove i ukrasno bilje. Postoje različite mere koje se mogu preduzeti za suzbijanje viline kosice, počev od preventivnih (čist semenski materijal, otporne sorte), preko mehaničkog uklanjanja (košenje, ručno uklanjanje) do korišćenja herbicida, ali je veoma teško postići efektivnu kontrolu ove parazitne cvetnice, zbog prirode vezivanja sa biljkom domaćinom. Za pravljenje dobre strategije u suzbijanju viline kosice pored integrisanja gore pomenutih mera, neophodno je i poznavanje njenog razvoja i životnog ciklusa

Avena fatua L. - divlji ovas

Avena fatua is widely distributed in diverse agro-ecosystems, from temperate to sub-tropical regions, due to its unique seed traits, successful germination ecology, high competitive ability and allelopathic potential. A. fatua infests major winter and spring crops, including wheat, oat, barley, canola, maize, alfalfa and sunflower, causing yield losses up to 70%, depending on the crop species and the density of wild oat. In addition to herbicide application, several cultural practices, including diverse crop rotations, cover crops, improved crop competition (using competitive cultivars, high seed rates, narrow row spacing, altered crop geometry) have shown promise for the control of A. fatua. An integrated use of these cultural methods can reduce the herbicide dose which is required and lower the dependency on herbicides in the control of this grass species. Moreover, integrated management may successfully control the herbicide-resistant populations of this weed species

Gene Flow from Herbicide-Resistant Crops to Wild Relatives

Development of herbicide-resistant (HR) crops is way to overcome problems in weed control due to weed resistance to herbicides and absence of new herbicides with a new mode of action for their control. Three types of HR crops were developed: nontransgenic, transgenic, and multiple HR crops. Cultivation of HR crops is associated not only with many benefits (simplification of weed control, more effective and efficient weed control, higher yields, etc.) but also with various risks (development of HR weeds, development of HR volunteer crops, gene flow from HR crops to susceptible relatives, etc.). The greatest risk is gene flow from HR crops to related weed species, wild relatives or conventional crops of the same species. Unwanted gene flow could be prevented or reduced using different barriers such as isolation in space or time, protective vegetation barriers, male sterility, etc. Sunflower hybrids resistant to herbicides (imidazolinones and sulfonilureas) was developed by conventional breeding methods, and their introduction in Serbian fields has enabled a more efficient control of harmful weed species, but the presence of huge populations of weedy sunflower is the main concern associated with their cultivation, because numerous studies have confirmed gene flow from sunflower to its relatives

Application of molecular methods in weed science

Molecular methods are useful tools for weed science, especially in the area of weed resistance to herbicides and gene flow from herbicide tolerant crops to their wild relatives. Also, genetic variability plays an important role in weed susceptibility to herbicides and affect on strategies of control. For all of these studies, DNA, as a starting material, could be extracted by various methods; though, the easiest and the most suitable is extraction by using commercially available kits. The most important part of molecular analysis is selection and design of adequate primers for successful DNA amplification. Usually, primer selection and designing are based on DNA sequences stored in GenBank. Analysis following selected DNA fragments will depend on type of research. For weed resistance or gene flow studies, amplified fragments are sequenced and obtained information compared with the GenBank sequence database, with the aim to check for mutation(s) presence. For genetic diversity of weed species analysis of amplified DNA fragments include Capillary Electrophoresis

Integrated weed management in field crops: sustainability and practical implementation

Integrated Weed Management (IWM) is a sustainable approach to the management of weeds by combining all available weed control techniques, including preventative measures, monitoring, crop rotations, tillage, crop competition, mechanical and physical control, herbicide rotation, herbicide mixtures, biological control, nutrition, irrigation, burning, etc. in a way that minimizes economic, health, and environmental risks. The first step in IWM program is to monitor the fields for signs of weed infestation or potential weed problems. Proper weed management involves a thorough survey of each field after crop harvest to identify major weed species in the field. When an annual crop (maize, sugar beet, soybean, wheat, etc.) is to be grown in the field in the following year, this information is used to assess the importance of each weed species and to select the appropriate management strategy to be used for the coming crop. In annual crops, fields are also monitored after the crop has emerged, to assess the effectiveness of the selected management alternative and whether additional management measures are needed. For planting perennial field crops, such as alfalfa, an assessment of weed species composition is conducted after harvest of the previous crop, to determine the appropriate management alternative to be used during the establishment. In an established crop, fields are monitored to determine the need for additional measures to manage annual, biennial and perennial weed species

Weed Resistance to Herbicides

Unfortunately, herbicide resistance developed shortly after the introduction of the herbicides 2,4‐D in 1957. According the herbicide resistance mechanisms, all processes can be grouped as follows: target‐site resistance, non‐target‐site resistance, cross‐resistance and multiple‐resistance. Target‐site resistance is generally due to a single or several mutations in the gene encoding the herbicide‐target enzyme, which, in turn, decreases the affinity for herbicide binding to that enzyme. Non‐target‐site resistance is caused by mechanisms that reduce the amount of herbicidal active compound before it can attack the plant through the reduced absorption or altered translocation, increased herbicide sequestration or enhanced herbicide metabolism. Cross‐resistance means that a single‐resistance mechanism causes resistance to several herbicides with some mode of action. Multiple‐resistance is a situation where two or more resistance mechanisms are present within the same plant, often due to sequential selection by herbicides with different modes of action. Currently, herbicide resistance has been reported in 478 weed biotypes (252 weed species) in 67 countries. Many of those biotypes are resistant to acetolactate synthase (ALS) inhibitors, PS II inhibitors, ACC‐ase inhibitors and EPSPS inhibitors. Strategy for herbicide‐resistance weed management must involve all the available preventive, cultural, mechanical and chemical measures for effective, safe and cost‐effective weed control

Parazitski korovi - osnovne karakteristike, taksonomija, biodiverzitet i rasprostranjenje, I - vilina kosica (Cuscuta L.)

The first part of this study provides the basic characteristics of dedder (Cuscuta L.). The most important data concerning the taxonomy, diversity and distribution of Cuscuta are presented. There are eighteen Cuscuta species in Europe, while ten species have been found in the Balkans, including Serbia. Various Cuscuta species are hereby described in detail from the standpoints of taxonomy, biodiversity and chorology. The survey also contains all the relevant data concerning the plants on which certain Cuscuta species live as parasites.Prvi deo ove studije obuhvata prikaz osnovnih karakteristika viline kosice (Cuscuta L.). Dati su najvažniji podaci o taksonomiji, biodiverzitetu i rasprostranjenju vrsta roda Cuscuta. Utvrđeno je da u Evropi egzistira 18 vrsta roda Cuscuta, a 10 na Balkanskom poluostrvu i Srbiji. Detaljno su opisane vrste viline kosice sa taksonomskog, biodiverzitctskog i horološkog stanovišta. Izneti su podaci i o biljkama na kojima parazitiraju pojedine vrste viline kosice

Korovi useva pšenice i mogućnosti njihovog suzbijanja

According survey of wheat crop in Serbia there are more than 250 weed species. The most annual and perennial harmful weed species in many wheat field in Serbia are: Avena fatua, Bilderdykia convolvulus, Cirsium arvense, Convolvulus arvensis, Calystegia sepium, Galium aparine, Galeopsis tetrahit, Galeopsis ladanum, Lamium purpureum, Lamium amplexicaule, Lolium perenne, Papaver rhoeas, Polygonum aviculare, Sinapis arvensis, Veronica hederifolia, Veronica persica, etc. Weeds need managing in wheat crop for a meny reasons: to protect crop yield and crop quality, to ensure easy of harvest, to prevent problems in following crops, to reduce spread of pest and diseases, and etc. An effective weed management program takes into account the type of weeds present, crop rotation, cultivation (ploughing, shallow), direct drilling, sowing data (early sowing), crop competition, mechanical weeding (finger tine), prevent weed seed spread and application of herbicides. Weed management should be planned across a whole rotation.Prema pregledu korovske flore useva pšenice na području Srbije utvrđeno je prisustvo više od 250 korovskih vrsta. Najčešće jednogodišnje i višegodišnje ekonomski štetne korovske vrste za našu zemlju su: Avena fatua, Bilderdykia convolvulus, Cirsium arvense, Convolvulus arvensis, Calystegia sepium, Galium aparine, Galeopsis tetrahit, Galeopsis ladanum, Lamium purpureum, Lamium amplexicaule, Lolium perenne, Papaver rhoeas, Polygonum aviculare, Sinapis arvensis, Veronica hederifolia, Veronica persica itd. Suzbijanje korova u usevu pšenice je neophodno izvoditi iz više razloga: da bi se zaštitio prinos i kvalitet zrna pšenice, osigurala lakša i efikasnija žetva useva, smanjili problemi u vezi korova u narednom usevu, smanjilo širenje fitopatogenih organizama i štetočina koje se razvijaju na korovima itd. Efikasno suzbijanje korova podrazumeva: poznavanje karte zakorovljenosti parcela, gajenje pšenice u plodoredu, obradu zemljišta (osnovna, predsetvena), vreme, dubinu i gustinu setve useva, negu useva, gajenje kompetitivnih sorti pšenice, mehaničko uklanjanje korova (plevljenjem), sprečavanje raznošenja semena korova i primenu herbicida. Prilikom pravljenja plana za suzbijanje korova u proizvodnji pšenice važno je kombinovati, odnosno rotirati navedene mere

Biološke invazije - na primeru korovskih biljaka

In the past two decades, ecologists have focused mainly on two basic aspects of biological invasions: firstly, the particular characteristics of species that determine their invasiveness, and secondly, on the properties of communities that determine their resistance to invasion. Depending on the period when it was unaccidental or accidental introduction of alien plant species, they are divided into four categories: archaeophytes, paleophytes, neophytes and neotophytes. In relation to the status after the introduction and the level of sustainability, alien plant species are grouped into: ephemeral, naturalized and invasive. In relation to the total invasive alien weed flora of the Republic of Serbia attribute most aggressive, in terms of crop production, can be assigned to species: Abutilon theophrasti Medic., Amaranthus retroflexus L., Ambrosia atremisiifolia L., Cuscuta campestris Yunk., Erigeron canadensis L., Galinsoga parviflora Cav., Iva xanthifolia Nutt., Polygonum aviculare L., Portulaca oleraceae L., Sorghum halepense (L.) Pers., Stenactis annua (L.) Ness. and Xanthium strumarium L. On the other hand, in the category of invasive alien weed species, which for now does not occur in a high abundance in the crop field, but that can be expected in the near future in the crop field if we do not take control measures, that’s are: Amaranthus deflexus L., Asclepias syriaca L., Ambrosia trifida L., Eleusine indica L., Solidago canadensis L., Kochia scoparia (L.) Schrad., Iva xanthifolia Nutt., Fallopia japonica Houtt., Xanthium spinosum L., etc.U poslednje dve decenije istraživanja u oblasti bioloških invazija su usmerena u dva pravca: 1) proučavanje ključnih biološko-ekoloških karakteristika vrsta koje im omogućavaju invazivnost, i 2) proučavanje karakteristika zajednice koje ukazuju na njenu otpornost prema opstanku novodospelih, odnosno unetih alohtonih vrsta. U zavisnosti od perioda kada je izvršena namerna ili slučajna introdukcija alohtonih biljnih vrsta one su podeljene u četiri kategorije: arheofite, paleofite, neofite i neotofite. U odnosu na status nakon introdukcije, odnosno nivo održivosti, alohtone vrste se grupišu u: efemerne, naturalizovane i invazivne. U odnosu na ukupnu alohtonu invazivnu korovsku floru R. Srbije atribut najagresivnije, sa aspekta biljne proizvodnje, se može dodeliti vrstama: Abutilon theophrasti Medik., Amaranthus retroflexus L., Ambrosia atremisiifolia L., Cuscuta campestris Yunk., Erigeron canadensis L., Galinsoga parviflora Cav., Iva xanthifolia Nutt., Polygonum aviculare L., Portulaca oleracea L., Sorghum halepense (L.) Pers., Stenactis annua (L.) Ness. i Xanthium strumarium L. S druge strane, u grupu invazivnih alohtonih vrsta se takođe svrstavaju agresivni korovi koji se za sada ne javljaju u značajnoj brojnosti na obradivim površinama, ali za koje se može očekivati da će u skorijoj budućnosti, ukoliko se ne preduzmu adekvatne mere kontrole, postati problem u usevima, takve su: Amaranthus deflexus L., Asclepias syriaca L., Ambrosia trifida L., Eleusine indica L., Solidago canadensis L., Kochia scoparia (L.) Schrad., Iva xanthifolia Nutt., Fallopia japonica Houtt., Xanthium spinosum L. i druge