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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 herbicida Weed 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 herbicides |
