Effect of crop rotation and fertilization on weed soil seed-bank

Rezerve semena korovskih biljaka predstavljaju nepresušni i stalni izvor zakorovljenosti s jedne strane, i deluju stabilizujuće na ekosistem i biodiverzitet u različitim sistemima biljne proizvodnje s druge strane. Poznato je da veličina, sastav i vertikalni raspored semena korova u zemljištu zavise od plodoreda, obrade zemljišta, đubrenja, nivoa primenjenih agrotehničkih mera, ako i nege useva koja uključuje i mere suzbijanja korova. Polazeći od toga da su ovi faktori u direktnoj korelaciji sa sadržajem semena korovskih biljaka u zemljištu programom ove doktorske disertacije predviđeno je da se definiše uticaj različitih sisitema biljne proizvodnje (monokulture, dvopolje, tropolje i različiti sistemi đubrenja) na rezerve semena u zemljištu a odabirom adekvatnog modela simulira rezerva semena u zemljištu. Istraživanja su izvedena na dugogodišnjem stacionarnom poljskom ogledu „Plodoredi” Instituta za ratarstvo i povrtarstvo, instituta od nacionalnog značaja za Republiku Srbiju, u okviru 16 tretmana: monokultura kukuruza i ozime pšenice đubrene mineralnim đubrivom (M-Km, M-Pm), monokultura soje bez đubrenja (M-S), dvopoljni plodoredi ozima pšenica-kukuruz sa i bez primene mineralnog đubrenja (D-PKm, D-KPm, D-PK, D-KP), tropoljni plodoredi ozima pšenica-soja-kukuruz sa i bez primene mineralnog i stajskog đubrenja (T-PSKm, T-KPSm, T-SKPm, T-PSKs, T-KPSs, T-SKPs, T-PSK, T-KPS, T-SKP). Zemljište je uzorkovano tokom šest sezona (J 2014 - P 2017) na svakom tretmanu na tri dubine (0-15, 15-30 i 30-40 cm). Metodom fizičke ekstrakcije semena (FE) procenjeno je da je najveća ukupna rezerva semena bila u monokulturi soje (M-S= 29.025 m-2) a najmanja u troplju sa primenom mineralnih đubriva (16.805 m-2), dok je metodom naklijavanja (NU) utvrđeno da je u monokulturi pšenice (M-Pm) 9.791 semena m-2 bilo spremno da klija, dok u tropolju sa primenom mineralanih đubriva klijavost je ispoljilo samo 3.969 semena m-2. Na osnovu α indeksa diverziteta [Simpson-ov indeks diverziteta i dominantnosti (D,D'), Shannon-ov indeks diverziteta i uniformnosti (H,H/Hmax)] i β indeksa potvrđeno je da je najmanji diverzitet i najveća neuniformnost korovske zajednice evidentirana u sistemu M-Pm (D= 0,8355; D'= 0,1642; H= 0,3259, H/Hmax= 0,1334, β indeks= 9-12), a najveći diverzitet i uniformnost korovske zajednice u sistemima tropoljnog plodoreda sa primenom mineralnog đubriva: T-PSKm, T-KPSm i T-SKPm (D= 0,1594; D'= 0,8406; H= 2,1344, H/Hmax= 0,6461, β indeks= 21-31). PCA analizom potvrđeno je da su korovske zajednice u M-Pm i M-Km siromašnije u odnosu na zajednice ostalih sistema biljne proizvodnje, a najbogatije u T-KPSm). ANN modelom potvrđeno je da na brojnost i sastav rezervi semena u različitim sistemima biljne proizvodnje najviše utiče interakcija plodored+đubrenje (64%), zatim interakcija plodored+đubrenje+dubina (30,52%), dok plodored kao pojedinačni fakor ima najmanji značaj (0,42%). Generalno može se konstatovati da na zemljišnu rezervu semena korova utiče veliki broj faktora i to: diverzitet lokalne korovske flore i vegetacije, generativni reproduktivni potencijal vrsta, sistemi gajenja useva, biološko-ekološke karakteristike semena, agroekološki uslovi, odnosno klimatske karakterisitke, tip i plodnost zemljišta, mere nege useva, kao i mere u suzbijanju korova uključujući i primenu herbicidaWeed seed-bank are an inexhaustible and permanent source of weeds, on the one hand, and have a stabilizing effect on the ecosystem and biodiversity in plant production systems, on the other hand. It is known that the size, composition and vertical distribution of weed seeds in the soil depend on crop rotation, tillage, fertilization, crop care, which includes weed control measures. Starting from the fact that these factors are in direct correlation with the content of weed seeds in the soil, the aim of this dissertation envisages defining the impact of different crop rotation (monocultures, 2-year crop rotation, 3-year crop rotation) and fertilization on weed seed-bank and by choosing an adequate model predict seed-bank in the soil. The research was performed at the long-term experiment "Plodoredi" of the Institute of Field and Vegetable Crops, National Institute of the Republic of Serbia within 16 treatments of maize and winter wheat monocultures fertilized with mineral fertilizer (M-Km, M-Pm), soybean monoculture without fertilization (M-S), 2-year crop rotations of winter wheat-maize fertilized with mineral fertilizer and without fertilization (D-PKm, D-KPm, D-PK, D-KP), 3-year crop rotation of winter wheat-soybean-maize fertilized with mineral fertilizer, manure and without fertilization (T-PSKm, T-KPSm, T-SKPm, T-PSKs, T-KPSs, T-SKPs, T-PSK, T-KPS, T-SKP). The soil was sampled during six seasons (A 2014-S 2017) at each treatment at three depths (0-15, 15-30 and 30-40 cm). The method of physical extraction of seed (FE) estimated that the largest total weed seed-bank in soybean monocutlure (M-S= 29.025 m-2), and the smallest in the 3-year field with mineral fertilization (16.805 m-2), while the method of germination (NU) was found that in winter wheat mococultures (M-Pm) 9.791 m-2 seeds were ready to germinate, while in the 3-year crop rotation with mineral fertilization, only 3.969 m-2 seeds showed germination. Based on the α diversity index (Simpson's diversity and dominance indices (D, D'), Shannon's diversity and uniformity index (H, H/Hmax)) and the β index, it was confirmed that the lowest diversity and the highest non-uniformity of the weed community were recorded in the M-Pm (D= 0.8355; D'= 0.1642; H= 0.3259, H/Hmax= 0.1334, β index= 9-12), and the highest diversity and community uniformity in 3-year crop rotation with mineral fertilization T-PSKm, T -KPSm and T-SKPm (D= 0.1594; D'= 0.8406; H= 2.1344; H/Hmax= 0.6461, β index= 21-31). PCA analysis confirmed that weed communities in M-Pm and M-Km are poorer than communities in other crop production systems, and the richest in T-KPSm. The ANN model confirmed that the number and composition of weed seed-bank in different management systems are most affected by the interaction of crop rotation+fertilization (64%), followed by the interaction of crop rotation+fertilization+depth (30.52%), while crop rotation as a single factor has the least importance (0.42%). In general, it can be stated that the weed seed-bank is influenced by a number of factors: diversity of local weed flora and vegetation, generative reproductive potential of species, crop systems, biological and ecological characteristics of seeds, climate and meteorological conditions, soil type and fertility, measures crop care, as well as weed control measures including the application of herbicide

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

REZERVE SEMENA KOROVSKIH BILJAKA U ZEMLJIŠTU U USEVU KUKURUZA GAJENOG U MONOKULTURI I DVOPOLJU

Proučavanje rezervi semena korovskih biljaka u zemljištu je od posebnog značaja, posebno sa aspekta utvrđivanja „praga tolerantnosti“ prisustva populacije određene korovske vrste i/ili grupe korova, kao i određivanja pravovremenih mera u njihovom efikasnom suzbijanju. Interakcija između načina obrade zemljišta, sistema gajenja i načina primene herbicida određuje brojnost i strukturu semena korova u zemljištu. U radu je prikazana analiza zakorovljenosti kukuruza gajenog u monokulturi i dvopolju na višegodišnjem stacionarnom ogledu “Plodoredi”, Instituta za ratarstvo i povrtarstvo iz Novog Sada (N 45°19', E 19°50'). U cilju određivanja rezervi semena korovskih biljaka uzeti su uzorci zemljišta sa tri dubine: 0-15 cm, 15-30 cm i 30-40 cm. Za izdvajanje rezervi semena primenjen je metod ekstrakcije semena, odnosno ispiranje uzoraka zemljišta kroz sistem sita. Determinacija je izvršena pomoću binokulara i uz korišćenje adekvatnih priručnika za determinaciju. Dobijeni rezultati istraživanja su pokazali da je u monokulturi kukuruza na dubini od 0 do 15 cm dominantno učešće imalo 9 korovskih vrsta iz 6 familija, a u dvopolju 13 vrsta (iz 10 familija). Sa dubine 15-30 cm iz monokulture kukuruza izdvojena su semena 7 korovskih vrsta (iz 5 familija), dok je u sistemu gajenja kukuruzpšenica determinisan dvostruko veći broj semena korova iz 12 familija. U sloju zemljišta 30-40 cm u monokulturi kukuruza konstatovana su semena 5, a u dvopolju semena 14 korovskih vrsta. Na osnovu utvrđenih rezervi semena korova najveća brojnost u dugogodišnjoj monokulturi kukuruza zabeležena je za sledeće korovske vrste: Amaranthus retroflexus L., Chenopodium album L., i C. hybridum L., Solanum nigrum L., Datura stramonium L., Sorghum halepense L. U rotaciji useva kukuruz-pšenica, pored navedenih, značajno prisustvo semena korova utvrđeno je i za korovske vrste Consolida regalis S.F. Gray., Anagalis arvensis L., Veronica hederifolia L., Bilderdykia convolvulus L., Geranium dissectum L., Avena fatua L. i Lamium purpureum L

Studies on gene flow from herbicide resistant to weedy sunflower

Gene flow is a main concern associated with the use of herbicide resistant sunflower crops because it could transfer herbicide resistance traits to weedy sunflower. In order to estimate potential gene flow from imazamox and tribenuron-methyl resistant sunflower hybrids to weedy sunflower, field experiments and DNA analysis were conducted. The progeny of weedy sunflower which grown near imazamox (WS1) and tribenuron-methyl (WS2) resistant hybrid in previous experiments were used. In the field experiment, recommended rates of imazamox and tribenuron-methyl were applied to WS1 and WS2, respectively, and plants surviving were recorded. Herbicides effect on fresh weight of survived plants were also determined. The presence of mutations responsible for sunflower resistance to herbicides (imazamox and tribenuron-methyl) checked based on DNA analysis of selected survived plants. Percentage of survived plants in field experiment was recorded at maturity and depend on weedy sunflower accession (WS1 or WS2) and distance of their mother plants from resistant sunflower hybrid in previous experiment and was higher for WS2 (50.25%) than for WS1 (24.50%). As DNA analysis were not confirmed the presence of the point mutations responsible for sunflower resistance to imazamox and tribenuron-methyl

Transfer gena odgovornih za tolerantnost na herbicide sa useva na divlje srodnike

Due to an intesive growing of crops tolerant to herbicides, obtained by conventional breeding methods or by genetic engineering (genetically modified - GM crops), interest for studies of gene transfer from crops to wild relatives has increased in the last two decades. This paper provides an overview of the risks associated with growing crops tolerant to herbicides, with the most attention paid to transfer of genes responsible for tolerance through pollen. Also, potential barriers for prevention of this problem were analyzed. Considering that sunflower hybrids tolerant to herbicides cultivate in our country, potential risks of gene transfer from these hybrids to wild relatives were discussed. A study of the transfer of genes responsible for tolerance to herbicides has mostly been limited to the hybrid offspring of the F1 generation so far. However, research in this area in the future should be focused on the long-term effects of this phenomenon studies.Usled sve učestalijeg gajenja useva tolerantnih na herbicide, bilo da su dobijeni klasičnim metodama oplemenjivanja (netransgeni usevi) ili primenom genetičkog inženjeringa (trans- geni tj. genetički modifikovani (GM) usevi), interesovanje za proučavanje transfera gena sa useva na divlje srodnike je poraslo u poslednje dve decenije. U ovom radu je dat pregled rizika povezanih sa gajenjem useva tolerantnih na herbicide, pri čemu je najviše pažnje posvećeno transferu gena odgovornih za tolerantnost putem polena. Takođe, sagledane su i potencijalne barijere za sprečavanje ove pojave. S obzirom da se kod nas gaje hibridi suncokreta tolerantni na imidazolinone i tribenuron-metil, razmotreni su i potencijalni rizici od transfera gena sa ovih hibrida na divlje srodnike. Proučavanje transfera gena odgovornih za tolerantnost na herbicide do sada je uglavnom bilo ograničeno na hibridno potomstvo F1 generacije. Ipak, istraživanja u ovoj oblasti u budućnosti treba usmeriti na proučavanje dugotrajnih efekata ove pojave

Estimation of active soil weed seed bank

Poznavanje i razumevanje veličine i sastava rezerve semena korovskih biljaka može pomoći kod planiranja uspešne i pravovremene strategije suzbijanja korova i procene dinamike pojave korova. Veoma je značajano imati u vidu u kom procentu će latentna biljna zajednica preći u aktivnu zajednicu. Metodom naklijavanja dobija se broj i struktura semena korovskih biljaka koja su prošla fazu mirovanja. Utvrđeno je da u monokulturi soje od ukupne procenjene rezerve semena korovskih biljaka preko 25,9% je spremno da klija, dok u tropoljnom plodoredu 23,61% semena. Najveći broj klijalih semena potiče od korovskih vrsta Chenopodium album i Chenopodium hybridum.Knowledge and understanding of the size and composition of soil weed seed reserves can help in planning a successful and timely weed control strategy and assessing the dynamics of weed emergence. It is very important to have an insight into what percentage of the latent plant community will pass into the active community. The seedling emergence method gives the number and structure of seeds that have passed the dormancy phase. It was determined that in the monoculture of soybean 24.9% of seeds are ready to germinate out of the total estimated weed seed bank, while in the three-field crop rotation 23.61% of seed. The largest number of germinated seeds comes from the weed species Chenopodium album and Chenopodium hybridum

Morfologija semena odabranih vrsta korovskih biljaka

In order to cope with all the natural phenomena and survive on different types of soil and in different climatic conditions, plants have perfected their means of propagation. Weed seeds are characterized by high diversity in all segments, both physical and chemical. Knowledge of the morphological characteristics of seeds and fruits of weed plants (mass, size, shape, colour, luster, odor, appearance of surface structures) is of great importance in the planning of weed control measures. The subject of this study were the seeds of the species Chenopodium album, C. hybridum, Anagallis arvensis, Veronica hederifolia and Amaranthus retroflexus, which were isolated during the weed seed bank assessment in the soil. After the physical extraction from the soil samples, the seeds were separated from the admixture, determined and then photographed with a stereomicroscope. The dimensions (length, width, seed thickness and length of the navel) were measured and any changes in the seed coat produced as a result of physical damage were monitored. The aim of this research was to expand the database, which should contribute to a more efficient determination of weed seeds. It was found that the seeds of the species studied in this paper were often broken and damaged, although in most cases with similar morphological features, as indicated by the literature data. The seeds of the species C. album were an exception, with dimensions significantly different from the data available in the literature. This occurrence can be explained by the diversity of seed anatomy in the Chenopodiaceae family and also by the fact that during their stay in the soil, permanent changes in the seed surface structures are possible.Da bi se izborili sa svim pojavama prirode i opstali na različitim tipovima zemljišta i različitim klimatskim uslovima biljke su usavršile svoje načine širenja. Seme korova se odlikuje velikom raznolikošću u svim segmentima, kako fizičkim tako i hemijskim. Poznavanje morfoloških osobina semena i plodova korovskih biljaka (masa, veličina, oblik, boja, sjaj, miris, izgled površinskih struktura) ima veliki značaj u planiranju mera za suzbijanje korova. Predmet istraživanja ovog rada bila su semena vrsta Chenopodium album, C. hybridum, Anagallis arvensis, Veronica hederifolia i Amaranthus retroflexus izdvojena tokom procene rezerve semena korovskih biljaka u zemljištu. Nakon fizičke ekstrakcije iz zemljišnih uzoraka semena su odvojena od primesa, urađena je determinacija semena a zatim su semena slikana stereomikroskopom. Izmerene su dimenzije (dužina, širina, debljina semena i dužina pupka) a praćene su i eventualne promene na semenjači koje su nastale kao posledica fizičkih oštećenja. Cilj ovog istraživanja je proširivanje baze podataka koja bi trebalo da doprinese efikasnijoj determinaciji semena korovskih vrsta. Ustanovljeno je da su semena vrsta koja su bila predmet proučavanja u ovom radu često bila polomljena i oštećena, mada u većini slučajeva sličnih morfoloških osobina kao što ukazuju podaci iz literature. Izuzetak su bila semena vrste C. album, čije su se dimenzije značajno razlikovale od podatka dostupnih u literature. Ova činjenica se može objasniti raznolikošću anatomske građe semena vrsta iz familije Chenopodiaceae ali i saznanjem da je tokom boravka semena u zemljištu moguća trajna promena površinske strukture

Uticaj plodoreda na rezerve semena korovskih biljka u zemljištu

Crop rotation, soil cultivation and weed control measures are in direct correlation with the content of the weed seed bank in the soil. Knowing the weed seed bank and the dynamics of the weed emergence is the basis for planning and implementing the measures for effective weed control. The research was carried out on the plots of the long-term stationary experiment 'Plodoredi' of the Institute of Field and Vegetable Crops in Novi Sad. During August of 2014, following the soybean harvest, the soil from the plots under different cultivation systems was sampled: soybean monoculture and 3-field (soybean, wheat, corn). Two methodological procedures were used to evaluate the reserve of seeds in the plough layer and the under plough soil layer. The physical extraction of seeds has determined the total content of weed species in the seed bank, while seed germinarion was used to determine which of the observed species are capable of germinating in the following period. The method of physical extraction has determined that the highest number of seeds was present in the soil samples from the soybean monoculture, in the depth layer of 15-30 cm. The under plough soil layer was characterized by a lower number of seeds, in both variants. In the study of germination, which was conducted under controlled conditions 18 months after the sampling, the best seed germination was recorded for the seeds of Ambrosia artemisiifolia L., Chenopodium hybridum L. and Chenopodium album L.Plodored, obrada zemljišta i nega useva koja uključuje mere suzbijanja korova su u direktnoj korelaciji sa sadržajem rezervi semena korovskih biljaka u zemljištu. Poznavanje rezervi semena i praćenje dinamike pojave korova je osnova u planiranju i sprovođenju mera za efikasno suzbijanje korova. Istraživanje je sprovedeno na višegodišnjem stacionarnom ogledu 'Plodoredi' Instituta za ratarstvo i povrtarstvo u Novom Sadu. Tokom meseca avgusta 2014. godine, nakon žetve soje uzorkovano je zemljište sa parcela pod različitim sistemom gajenja: monokultura soje i 3-polje (soja, pšenica, kukuruz). Za procenjivanje rezervi semena korovskih biljaka oraničnog i podoraničnog sloja korišćena su dva metodološka postupka. Fizičkom ekstrakcijom semena utvrđena je ukupna zastupljenost semena korovskih vrsta u rezervi semena, dok su naklijavanjem utvrđene vrste čija su semena sposobna da klijaju u narednom periodu. Metodom fizičke ekstrakcije utvrđeno je da je najveća brojnost semena bila u sistemu monokulture soje iz sloja zemljišta 15-30 cm. Podoranični sloj je generalno u obe varijante sadržao značajno manji broj semena. U ogledu za naklijavanje, koji je sproveden u kontrolisanim uslovima 18 meseci nakon uzorkovanja, najveću klijavost semena pokazale su vrste: Ambrosia artemisiifolia L, Chenopodium hybridum L., i Chenopodium album L

Hibridna forma divljeg suncokreta - Helianthus annuus L.

Weedy forms of Helianthus annuus L. are morphologically clearly different from the hybrids and volunteer plants. The main traits distinguishing weedy sunflower are strong branching without apical dominance, production of many seed heads, reduced size of the seed head and achene in comparison with the cultivated sunflower, seed dormancy and shattering. Hybridization between cultivated and their volunteer or weedy (or wild) sunflower is inevitable in regions of traditional sunflower crop production. Weedy sunflower is a large problem in whole area in Balkan Peninsula where sunflower planting, like as in Hungary, Croatia, Romania, Serbia and etc. Those plants have adapted to different environment in an undesired way, becoming harmful and invasive weeds such it was happened in Banat, Bačka, Srem and Belgrade area. Weedy sunflower can emerge during the row crops cycle (maize, sugerbeet, sunflower, soybean etc) and cause considerable yield losses if present at high densities. Introduced in the production system tolerant sunflower hybrids are at risk of gene flow from tolerant crop to weedy sunflower to form resistant weedy populations. Stewardship programs for imidazolinone and sulfonilurea tolerant crops have been developed and implemented to reduce gene flow and weed resistance and to preserve these effective weed-management tools.Hibridna forma divljeg suncokreta Helianthus annuus L. je veoma srodna gajenom suncokretu, od kojeg se razlikuje po jakom grananju, visini biljaka, prisutnosti pigmenta antocijana u različitim organima, mnogobrojnim glavicama, relativno malim ahenijama koje se oslobađaju tokom zrenja, dormantnosti i lomljivosti semena itd. Gajeni i divlji suncokret su reproduktivno kompatibilni i istraživanja su pokazala da se mogu lako ukrštati kada rastu u blizini. Na našim prostorima, hibridne frome divljeg suncokreta su u invaziji i najveće populacije su zastupljene na području Banata, Bačke, Srema i u okolini Beograda. Između populacija ovih formi divljeg suncokreta jako je izražena varijabilnost. Ove korovske biljke sa neobradivih površina i rubova parcela često prodiru u okopavinske useve (kukuruz, soja, suncokret, šećerna repa) i dovode do značajnih gubitaka u prinosu. Uvođenjem u proizvodnju hibrida suncokreta tolerantnih na herbicide ALS inhibitore stvara se potencijalni rizik od protoka gena sa hibrida u hibridne forme divljeg suncokreta i dobijanja rezistentnih korovskih populacija

Uticaj spoljašnjih faktora na mirovanje i klijanje semena korovskih biljaka

This work present two basic biological processes of seed dormancy and germination. Seed dormancy can be characterized as a basic for survival maintenance and expansion in agroecosystem, while, germination is the initial stage of plant development. Based on the research results of a large number of researchers, the work especially shows the behavior of weed seeds in the influence of the most important enviromental factors (water, temperature, light, soil), as well as the laws that govern these processes. Knowing reserves of weed seeds in the soil and their biological and ecological characteristics it is possible to predict when and how many seeds will germinate under certain climatic and soil conditions. A model for the evaluation of the appearance of weed plants and their effective in suppression of a given crop can be made, as well as an assessment on the potential invasiveness of cerain weed species.U radu su prikazana dva osnovna biološka procesa semena, mirovanje (dormantnost) i klijanje. Mirovanje semena se može okarakterisati kao osnov njegovog preživljavanja, održavanja i širenja u agroekosistemu, dok klijanje predstavlja početnu etapu razvoja biljke. Na osnovu rezultata istraživanja velikog broja istraživača u radu je posebno ukazano na ponašanje semena korovskih biljaka pri uticaju najvažnijih faktora spoljašnje sredine (voda, temperatura, svetlost, zemljište), kao i zakonitosti koji vladaju u ovim procesima. Poznavanjem rezervi semena korovskih biljaka u zemljištu i njihovih biološko-ekoloških osobina, moguće je predvideti kada i koliko semena će klijati u određenim klimatskih i zemljišnim uslovima. Odnosno, može se napraviti model za procenu pojave korova i njihovog efikasnog suzbijanja u određenom usevu, kao i procena potencijala invazivnosti neke korovske vrste