Mikoze kukuruza

Corn diseases cause harvest losses, affect the quality of the harvested crop and cause storage losses. The most common diseases are caused by fungi. The worldwide annual loss caused by fungi is about 9 %. Some of them produce mycotoxins, which in small amounts may be deleterious to animal and human health. The most important parasitic corn diseases can be classified into the following groups: seed rots and seedling blights, leaf diseases, stalk rot and ear root or moulds, smuts, rusts and downy mildews. Fusarium graminearum and F. verticillioides belong to the group of the most destrucive pathogens of seeds and seedlings, the most important disease type mouldiness grain, ear and stalk rot. In some years, northern corn leaf spot can seriously decrease productivity of parental lines in seed production fi elds. Moderate temperature and high relative humidity favour the disease. Ustilago maydis is an economically important disease that occurs in our country every year. Stressful conditions until flowering promote development of disease.Najčešći i najbrojniji prouzrokovači bolesti na kukuruzu jesu gljive. Njihova štetnost je izraženija u odnosu na druge prouzrokovače bolesti, zbog sposobnosti nekih da stvaraju toksine, odnosno sekundarne metabolite koji su toksični ili imaju neke druge negativne biološke efekte po zdravlje ljudi i životinja. Smanjenje prinosa zrna, kao posledica bolesti prouzrokovanim gljivama, procenjuje se prosečno na oko 9 % svetske proizvodnje. Mnoge od njih godinama žive saprofi tski i samo u određenim uslovima javljaju se kao paraziti biljaka. Najvažnije parazitne bolesti kukuruza mogu se svrstati u sledeće grupe: bolesti semena i klijanaca, bolesti lista, bolesti nadzemnih organa, truleži korena i klipa i bolesti tipa plesnivosti klipa i zrna. Fusarium graminearum i Fusarium verticillioides spadaju u grupu najčešćih patogena zrna i klijanaca, najznačajnijih oboljenja tipa plesnivosti zrna i klipa i najdestruktivnijih prouzrokovača truleži stabla i klipa kukuruza. Prouzrokovači pegavosti lista pojavljuju se u jačem intenzitetu kada početkom leta preovlađuje umereno toplo i vlažno vreme, a najznačajniji je Bipolaris zeicola. Ustilago maydis predstavlja ekonomski značajnu bolest koja se kod nas javlja svake godine. Stresni uslovi do faze cvetanja kukuruza pospešuju razvoj oboljenja

Viroze kukuruza - realna ekonomska opasnost ili samo neosnovan strah

Maize viral diseases can be found anywhere in the world where maize is grown. The most widely spread and harmful ones in the northern hemisphere in general and Yugoslavia in particular are two viruses of the genus Potyvirus, the Maize Dwarf Mosaic Potyvirus and Sugarcane Mosaic Potyvirus. In recent years, viruses that cause maize dwarf mosaic have been increasingly spreading in our country, where they have become a real economic threat. In some years that are favorable for the development of the virus vector and an abundance of the disease sources (Johnsongrass), outbreaks of maize dwarf mosaic reach epidemic proportions and cause huge amounts of damage by reducing the yields of commercial maize by about 20% and those of seed maize by about 70%. The disease symptoms manifest themselves in the form of striped white-yellowish mosaic that appears on the leaves. The growth of systemically infected plants is stunted. Diseased plants form short ears that sterile to a greater or lesser extent. The Maize Dwarf Mosaic Potyvirus and Sugarcane Mosaic Potyvirus are both elongated viruses with a single-strand infective ribonucleic acid (RNA). They belong to the genus Potyvirus of the Potyviridae family. These viruses parasitize around 200 other species from the Poaceae family in addition to maize and Johnsongrass. They are spread by 23 leaf aphid species, the most important among which are Rhopasosiphon maydis, Myzus persicae and some others. The biggest source of infection in the wild is Johnsongrass (Sorghum halepense). There are a number of measures, all of them preventive, that can help reduce the incidence of maize viral diseases and their harmfulness. They include the eradication of weeds that host the viruses, an earlier sowing, and the growing of less susceptible or tolerant hybrids. The most effective way to protect maize crops, minimize the damage, and prevent the incidence of these viruses is to develop genotypes that are resistant to the prevalent viruses in a given area. The results of studies on maize resistance to the Maize Dwarf Mosaic Potyvirus and Sugarcane Mosaic Potyvirus confirm the existence of sources of resistant genotypes (both domestic and foreign) that can be used as sources of desirable genes in maize breeding. Resistance to the Sugarcane Mosaic Potyvirus is controlled by two dominant genes Scm1 and Scm2, and so is resistance to the Maize Dwarf Mosaic Potyvirus (genes Mdm1 and Mdm2).Viroze kukuruza predstavljaju realnu ekonomsku opasnost kako u svetu tako i u našoj zemlji. Najznačajnija i ekonomski najopasnija viroza kukuruza je mozaična kržljavost. Ovo obolenje u našoj zemlji prouzrokuje virus mozaične kržljavosti kukuruza (maize dwarf mosaic potyvirus) i virus mozaika šećerne trske (sugarcane mosaic potyvirus). Ovi virusi poslednjih godina pokazuju sve veću ekspanziju širenja kod nas i predstavljaju veliku ekonomsku opasnost u proizvodnji kukuruza, smanjujući prinose merkantilnog kukuruza za oko 20% i semenskog za oko 70% u godinma povoljnim za širenje virusa. Najefikasniji način zaštite kukuruza i smanjenja štetnosti virusa je stvaranje otpornih genotipova prema prevalentnim virusima za dato područje. Utvrđeno je da postoje izvori otpornih genotipova, kako domaćeg tako i stranog porekla, koji se mogu koristiti kao izvori poželjnih gena u selekciji kukuruza. Otpornost prema virusima,prouzrokovačima mozaične kržljavosti je kontrolisana sa dva dominantna gena Mdm 1 i Mdm 2 a otpornost prema VMŠT takođe sa dva dominantna gena Scm 1 i Scm 2

Genetička analiza svojstava tolerantnosti prema suši u sintetičkim populacijama kukuruza

Maize breeders consider tolerance to drought as an important criterion in commercial breeding programs. Two traits, stay green and anthesis-silking interval seem to be closely associated with drought tolerance. The main objective of this study was to obtain estimates of means, variability, heritability and estimates of genetic correlations for several traits in two maize synthetic populations. S1 progenies were evaluated in an incomplete block design in four environments. Large genetic variability existed for all traits in both populations but highest variability was found for anthesis-silking interval. Strong, highly significant correlations between drought adaptive traits and grain moisture may cause some undesirable correlative response throughout cycles of selection.Oplemenjivači kukuruza smatraju tolerantnost prema suši jednim od najznačajnijih kriterijuma u komercijalnim oplemenjivačkim programima. Čini se da su dva svojstva, zakašnjenje u svilanju i stay green tesno povezani sa tolerantnošću prema suši. Cilj ovog rada bio je da se odrede srednje vrednosti, varijabilnost, heritabilnost i genetičke korelacije za nekoliko svojstava u dve sintetičke populacije kukuruza. Vrednosti S1 potomstava ocenjivane su u nepotpunom blok dizajnu na četiri lokaliteta. Utvrđena je zadovoljavajuća varijabilnost svih svojstava u obe populacije, a najveća za zakašnjenje u svilanju. Visoko signifikantne korelacije između svojstava tolerantnosti prema suši i sadržaja vlage u zrnu mogu biti uzrok nepoželjnih korelativnih odgovora kroz cikluse selekcije

Screening of different trichoderma isolates as antagonists of various maize phytopathogens

The increasing use of chemical plant protection agents in recent years has become a serious problem. Environmental pollution, non-selectivity, the emergence of resistant species, and chemicals in the food chain, has led to need to find new agents with improved characteristics. One of the solutions is certainly the use of beneficial microorganisms. The genus Trichoderma is genetically very diverse with a number of capabilities among different strains with agricultural and industrial significance. Maize is an agricultural crop that is susceptible to infections by various phytopathogenic fungi, producers of mycotoxins harmful to humans and animals. Since this agricultural crop has an important place in the human diet, its health safety is very important. In this work, the screening of antagonistic activity of three Trichoderma isolates, isolated from the environment, against the most common maize phytopathogens, was examined using dual culture technique. The results showed that there is a statistically very significant difference between the applied Trichoderma isolates. Using the Scheffe test, it was determined that the isolate of Tricoderma harzianum shows the best effect on the tested phytopathogens of maize by forming Radial Growth Inhibition (RGI) of 100% for Penicilium sp., 53.67% for Helminthosporium carbonum, 52.33% for Fusarium graminearum and 35% for Aspergillus flavus. Considering that Trichoderma spp. isolates were considered as effective when RGI exceeded 50%, from the obtained results it can be concluded that T. harzianum shows a very significant effect on all phytopathogenic isolates. It shows slightly weaker activity only on isolate A. flavus. This result once again confirms the great antagonistic potential of Trichoderma isolates and their use in biological control would contribute to the development of sustainable agricultural production and would affect the healthier environment

Influence of process parameters on the production of Trichoderma biocontrol agent

Maize is an agricultural crop that is susceptible to infections by various phytopathogenic fungi, producers of mycotoxins harmful to humans and animals. Since this agricultural crop has an important place in the human diet, its health safety is very important. Trichoderma genus has great potential in the biocontrol of various phytopathogens however, the medium composition as well as the cultivation conditions, have a significant impact on the efficiency of the produced Trichoderma bioagents. In this work, influence of medium pH, temperature and mixing speed on the productivity of Trichoderma bioagent effective against two maize pathogens, Fusarium graminearum and Aspergillus flavus, was investigated. The results obtained by statistical processing show that the best productivity of Trichoderma harzianum bioagent was achieved when the pH of the medium was 6, the temperature was 28°C and the mixing speed of the rotary shaker was 180 rpm. By applying these cultivation conditions, the largest inhibition zone diameters of F. graminearum and A. flavus mycelial growth were formed. Also, the results show that the maize pathogen, F. graminearum, was more sensitive to the produced Trichoderma biocontrol agent compared to the other maize pathogen, A. flavus

Influence of process parameters on the production of Trichoderma biocontrol agent

Maize is an agricultural crop that is susceptible to infections by various phytopathogenic fungi, producers of mycotoxins harmful to humans and animals. Since this agricultural crop has an important place in the human diet, its health safety is very important. Trichoderma genus has great potential in the biocontrol of various phytopathogens however, the medium composition as well as the cultivation conditions, have a significant impact on the efficiency of the produced Trichoderma bioagents. In this work, influence of medium pH, temperature and mixing speed on the productivity of Trichoderma bioagent effective against two maize pathogens, Fusarium graminearum and Aspergillus flavus, was investigated. The results obtained by statistical processing show that the best productivity of Trichoderma harzianum bioagent was achieved when the pH of the medium was 6, the temperature was 28°C and the mixing speed of the rotary shaker was 180 rpm. By applying these cultivation conditions, the largest inhibition zone diameters of F. graminearum and A. flavus mycelial growth were formed. Also, the results show that the maize pathogen, F. graminearum, was more sensitive to the produced Trichoderma biocontrol agent compared to the other maize pathogen, A. flavus

Yugoslav local germplasm in hybrid maize breeding

When the spread of hybrid maize began in the mid-20th century, local breeding materials were collected and assembled in gene banks in order to prevent their deterioration and enable their utilization in breeding to develop hybrid varieties. Numerous inbred lines from local populations were selected. The present study includes only those lines from the first cycle of selection that were used for the development of commercial hybrids. The contribution of domestic inbred lines to modern maize breeding consists in the following: 1) Domestic inbred lines possess great variability for most of the agronomically important traits. In nearly every group of lines (lines of the same origin comprise one group), lines with desirable traits have been found, lines that now represent new sources of variability in breeding programs on: grain yield, resistance to lodging, early maturity, ear bareness, grain quality and other traits. 2) The domestic inbreds differ in their heterotic potential for grain yield when crossed with the inbred testers B73 (BSSS germplasm) and Mo17 (Lancaster Sure Crop germplasm). Lines originating from the populations Vukovarski Žuti Zuban, Šidski Žuti Zuban, Novosadski Zlatni Zuban, and Novosadski Žuti Zuban combine better with the inbred tester Mo17 than with B73, so they belong to the BSSS heterotic group. Lines originating from the populations Bankut Bajsa and Sočice are neutral, i.e. they respond equally to both types of germplasm (BSSS and Lancaster), so they can be said to belong to a new heterotic group

Biocontrol potential of different trichoderma isolates against maize phytopathogens

Usage of chemical plant protection agents in agricultural production contributes to environmental pollution and emissions of factors harmful for human health. It has been noted that their overexploitation has resulted in the emergence of resistant species and chemical compounds in the food chain, which indicates the need to find new agents with improved characteristics. One of the solutions is certainly the use of beneficial microorganisms. Considering that maize is a significant agricultural crop very present in the human diet, its health safety is of great importance. In this paper, the ability of three Trichoderma isolates, isolated from the environment, in the biological control of the most common maize pathogens, was examined. Cultivation of Tricoderma isolates was performed on PDB (Potato Dextrose Broth) medium by shaking at 150 rpm for 7 days at 25°C. After 7 days of cultivation, the effect of both, cultivation broth and supernatant, against selected maize phytopathogens was examined using wells diffusion technique. The results showed that the cultivation broth showed a statistically significant efficacy on selected maize phytopathogens compared to the supernatant, using all Trichoderma isolates. By applying the Scheffe test, it was determined that the best effect on the test maize phytopathogens show cultivation broth of T. harzianum, forming maximum mean inhibition zone diameters of 50.33 mm for Fusarium graminearum, 40.67 mm for Helminthosporium carbonum, 25.67 mm for Aspergillus flavus and 25.33 mm for Penicillium sp. Since each inhibition zone larger than 22 mm shows that the produced agent is highly efficient, based on the obtained inhibition zone diameters of all tested isolates, it can be concluded that the produced T. harzianum cultivation broth shows high efficacy against four maize phytopathogens in vitro. This results once again confirms the great potential of Trichoderma isolates in biological control, which certainly contributes to the development of sustainable agricultural production and consequently has a positive impact on human health

Kiselost i sadržaj pokretljivog aluminijuma u pseudoglejnim zemljištima Čačansko-kraljevačke kotline

Soil acidity and aluminum toxicity are considered the most damaging soil conditions affecting the growth of most crops. This paper reviews the results of tests of pH, exchangeable acidity and the mobile aluminum (Al) concentration in profiles of pseudogley soils from the Čačak-Kraljevo Basin. For these purposes, 102 soil pits were dug in 2009 in several sites around the Čačak-Kraljevo Basin. The tests encompassed 54 field, 28 meadow, and 20 forest soil samples. Samples of soil in a disturbed state were taken from the Ah and Eg horizons (102 samples), from the B1tg horizon in 39 field, 24 meadow and 15 forest pits (a total of 78 samples) and from the B2tg horizon in 14 field, 11 meadow, and 4 forest pits (a total of 29 samples). The mean pH values (1 M KCl) of the tested soil profiles were 4.28, 3.90 and 3.80 for the Ah, Eg and B1tg horizons, respectively. The soil pH of the forest samples was lower than those in the meadow and arable land samples (mean values of 4.06, 3.97 and 3.85 for arable land, meadow and forest samples, respectively). The soil acidification was especially intensive in the deep horizons; thus, 27 (Ah), 77 (Eg) and 87 % (B1tg) of the soil samples had a pH value below 4.0. The mean values of the total exchangeable acidity (TEA) were 1.55, 2.33 and 3.40 meq (100 g)-1 for the Ah, Eg and B1tg horizons, respectively. The TEA values in the forest soils were considerably higher (3.39 meq (100 g)-1) than those in the arable and meadow soils (1.96 and 1.93 meq (100 g)-1, respectively). The mean mobile Al contents of the tested soil samples were 11.02, 19.58 and 28.33 mg Al (100 g)-1 for the Ah, Eg and B1tg horizons, respectively. According to the pH and TEA values, mobile Al was considerably higher in the forest soils (a mean value of 26.08 mg Al (100 g)-1) than in the arable and meadow soils (mean values of 16.85 and 16.00 mg Al (100 g)-1, respectively). The Eg and B1tg horizons of the forest soil had especially high mobile Al contents (mean values of 28.50 and 32.95 mg Al (100 g)-1, respectively). High levels of mobile Al were especially frequent in the forest soils, with 35 (Ah), 85.0 (Eg) and 93.3 % (B1tg) of the tested samples ranging above 10 mg Al (100 g)-1.Kiselost zemljišta i toksičnost aluminijuma se smatraju najvažnijim faktorima koji ograničavaju rast biljaka na kiselim zemljištima. U ovom radu su ispitivani pH vrednost zemljišta i sadržaj pokretljivog aluminijuma (Al) u profilima zemljišta pseudogleja Čačansko-kraljevačke kotline. Ukupno 102 zemljišna profila su otvorena tokom 2009. godine na pojedinim lokalitetima Čačansko-kraljevačke kotline. Istraživanjima je obuhvaćeno 54 uzorka sa oranica, 28 sa livada i 20 uzoraka iz profila koji su otvoreni pod šumskom vegetacijom. Iz otvorenih profila, uzeti su uzorci zemljišta u poremećenom stanju iz Ah i Eg horizonta (102 profila), a zatim iz B1tg horizonta sa 39 oranica, 24 livade i 15 šumskih profila (ukupno 78) i iz B2tg horizonta 14 oranica, 11 livada i 4 šumska profila (ukupno 29). Prosečna pH vrednost (1 M KCl) ispitivanih zemljišnih profila je 4,28, 3,90 i 3,80, za Ah, Eg i B1tg horizonte. Takođe, pH vrednost zemljišta šumskih profila je niža u poređenju sa livadama i obradivim zemljištem (4,06, 3,97 i 3,85, za obradivo zemljište, livade i šume). Zemljišna kiselost je posebno izražena u dubljim horizontima, jer 27 (Ah), 77 (Eg) i 87 % (B1tg) zemljišnih profila imaju pH vrednost nižu od 4,0. Srednja ukupna razmenljiva kiselost (TEA) ispitivanih zemljišnih profila je 1,55, 2,33 i 3,40 meq (100 g)-1, u Ah, Eg i B1tg horizontima. Međutim, kod šumskim zemljištima TEA je znatno viša (prosečno 3,39 meq (100 g)-1) nego kod obradivog zemljišta i livada (1,96 i 1,93). Prosečan sadržaj pokretljivog Al u ispitivanim zemljištima je 11,02, 19,58 i 28,33 mg Al (100 g)-1, u Ah, Eg i B1tg horizontima. Usled razlika u pH i TEA vrednostima njegov sadržaj u šumskim zemljištima je znatno viši (prosečno 26,08 mg Al (100 g)-1) nego kod obradivog zemljišta i livada (16,85 i 16,00 Al (100 g)-1). Eg i B1tg horizonti šumskog zemljišta imaju posebno visok sadržaj pokretljivog Al (28,50 i 32,95 mg Al (100 g)-1). Učestalost visokog nivoa pokretljivog Al u šumskim zemljištima postoji zbog toga što 35 (Ah), 85.0 (Eg) i 93.3 % (B1tg) ispitivanih profila poseduju više od 10 mg Al (100 g)-1

Proizvodnja kukuruza u uslovima globalnih klimatskih promena

Climate changes and expected variability of climatic parameters represent a serious concern of the 21st century agriculture. At the global level, the further rise in temperature, changed quantity and distribution of precipitation, increased variability of climate parameters and the occurrence of extreme climate events are expected. In order to avoid, or at least reduce the negative effects of global climate change, several adaptation strategies are proposed. Adjustment of production technology and breeding for tolerance to changed environment are proposed as two most important adaptation measures.Klimatske promene i očekivana varijabilnost klimatskih parametara predstavljaju ozbiljan izazov za poljoprivredu 21. veka. Na globalnom nivou, očekuje se porast temperature vazduha, promene količine i rasporeda padavina, povećanje varijabilnosti klimatskih parametara i pojava ekstremnih klimatskih događaja. U cilju izbegavanja, ili barem redukovanja negativnih efekata globalnih klimatskih promena, predloženo je nekoliko adaptacionih strategija. Kao dve najznačajnije mere adaptacije predlažu se prilagođavanje tehnologije proizvodnje i oplemenjivanje biljaka na tolerantnost prema izmenjenim uslovima spoljašnje sredine