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

Effect of Trichoderma spp. on Growth Promotion and Antioxidative Activity of Pepper Seedlings

One of the main challenges in pepper production is to enhance seed germination energy and germination, and to grow healthy nursery plants with strong root system. Trichoderma species colonize roots as they grow and provide season-long benefits to plants, which is why Trichoderma species are widely used as plant growth promoter agents and promoters of plant defence mechanisms. This study evaluated the effectiveness of seed biopriming with Trichoderma isolates for growth promotion of pepper plants in early stage and their effects on seedling physiology. Nine out of ten Trichoderma isolates positively affected root weight of pepper seedlings, while three out of ten positively affected shoot weight. Root and shoot lengths were mainly unaffected. Germination energy was positively affected by five isolates with up to 40% increase compared to the control, while germination was significantly enhanced by two isolates with up to 22% increase. Considering seedling physiology, two different strain-dependent modes of actions were expressed. Promising Trichoderma isolates induced formation and accumulation of reactive oxygen species (ROS) which acted as signal molecules that increased germination energy and germination. Positive correlation was found between pyrogallol peroxidase, superoxide dismutase, catalase activity and germination in plants treated with these isolates

Current status of broomrape (Orobanche cumana Wallr.) in Serbia

Broomrape is the major issue in sunflower production in Serbia. Since its first occurrence, the species Orobanche cumana Wallr. had been responsible for considerable yield loss in some areas. In Serbia broomrape is present in the Vojvodina Province. Distribution and virulence groups of parasite are constantly monitored. Only two distinct broomrape populations currently exist in this part of country. Race B is dominant in the south of the Vojvodina Province and race E in the north. During 2008, sets of 8 commercial hybrids with different broomrape resistance genes were sown in regions with sunflower production. Hybrids were sown on 34 different locations. Presence of broomrape was confirmed on 6 sites. Occurrence of parasitic plants was not detected on cultivars resistant to race E. Sunflower fields in regions where broomrape was not previously detected, were surveyed. The survey revealed occurrence of broomrapes in new regions. Infested areas are located in Bor County near the state border with Romania and Bulgaria

Screening wild sunflower species and F1 interspecific hybrids for resistance to broomrape

Broomrape has become one of the most important threats to the cultivated sunflower. New sources of resistance genes are needed to maintain sunflower production. The objective of this research was to evaluate accessions of wild sunflower species and their F1 interspecific hybrids with cultivated sunflower for resistance to race E. Plant material consisted of 6 accessions of perennial species and 14 F1 accessions between perennial species and cultivated sunflower as well as 42 accessions of annual species. Cultivated line JM8 was used as the sensitive check. Accessions were screened in the greenhouse in the season of 2008/09 and in a field trial during 2009. Plants were grown in the infested soil and evaluated for reaction at the end of the vegetation. The cultivated check was susceptible in the greenhouse and in the field trial. The annual species showed varying resistance with H. annuus and H. argophyllus as the most sensitive with an average of 6.6 and 8.5 broomrape plants per sunflower plant. Only 2 of the 7 H. petiolaris accessions were susceptible. H. neglectus performed well in the greenhouse with only one broomrape plant infecting one plant of the four tested accessions, but accession NEG1363 was infected in the field trial leaving NEG457 and 1183 as resistant. All accessions of perennial species except for an F1 hybrid of DEC B and F1 RIG 707 showed complete resistance. New potential sources of broomrape resistance genes have been found among wild species and their interspecific hybrids

Uticaj Trichoderma spp. na klijavost semena soje i potencijalni antagonistički efekat na Sclerotinia sclerotiorum

Trichoderma species have been registered as species with important plant growth promoting potential and antagonistic effect against various phytopathogens. Trichoderma isolates originating from different soil types from the Vojvodina region (Serbia) were screened using dual culture test for their antagonistic effect against the pathogen Sclerotinia sclerotiorum. All tested isolates had high radial growth inhibition (RGI) factors of the pathogen and high colonization percentage. Growth promoting activity of Trichoderma isolates on soybean seeds was tested under glasshouse conditions. Soybean seeds were coated with suspensions of different Trichoderma isolates and seed germination percentage, root and shoot length were measured. According to data analysed in Statistica 10, using Duncan's test, there were no significant effects on shoot length among the tested isolates, compared to the control. The four tested Trichoderma isolates showed significant positive effects on germination, root length and vigour index, while two isolates exhibited no significant effect on any of the measured parameters.Vrste roda Trichoderma su poznate po svom antagonističkom efektu na veliki broj fitopatogenih organizama kao i po stimulativnom efektu za rast biljke. Izolati Trichoderma spp. testirani u ovom istraživanju su izolovani iz različitih tipova zemljišta u Vojvodini (Srbija). Test dvojnih kultura je korišćen za testiranje antagonističkog dejstva izolata na patogena Sclerotinia sclerotiorum. Svi testirani izolati su imali visok RGI (faktor inhibicije porasta micelije patogena) i visok procenat kolonizacije patogena. Stimulativni efekat rasta Trichoderma izolata na seme soje je testiran u uslovima staklenika, i sedmog dana su mereni dužina korena, izdanka i klijavost semena tretiranih suspenzijom različitih izolata Trichoderma spp. Svi podaci su analizirani primenom Duncan testa u programu Statistica 10, i ukazuju da nije bilo statistički značajne razlike u dužini izdanaka tretiranih semena i kontrole. Četiri izolata su statistički značajno uticala na povećanje dužine korena, klijavosti i vigor indeksa u odnosu na kontrolu, dok dva izolata nisu statistički značajno uticala ni na jedan od merenih parametara

Growth promoting activity of Trichoderma spp. on sunflower seedlings

Plants are constantly exposed to biotic and abiotic stress and are forced to e fficiently balance growth, reproduction and tolerance to different pathogenic organisms. Trichoderma species belong to beneficial fungi that are capable for root colonization which frequently enhances root growth and development, crop productivity, resistance to abiotic stress and nutrients uptake and utilization. Therefore, seed priming with Trichoderma spp. has successfully demonstrated to improve seed germination and seedling establishment for many field crops, such as wheat, sugar beet, maize, soybean, and sunflower. Due to that, objectives of this study was to test growth promoting ability of Trichoderma spp. isolates, which previously indicated good antagonistic activity, on sunflower seedlings. Trichoderma spp. isolates were obtained from soil samples originating from various soil types and localities in Serbia, but mainly from the Vojvodina Province, in 2012

Varijabilnost patogenih svojstava Fusarium spp. poreklom iz zrna kukuruza i pšenice

Differences in the pathogenicity of 93 isolates of seven species belonging to the genus Fusarium (F. graminearum, F. verticillioides, F. proliferatum, F. subglutinans, F. sporotrichioides, F. semitectum and F. equiseti), originating from maize kernels (61) and wheat grains (32), were examined based on the germination percentage of inoculated seeds. The studied species demonstrated inter- and intraspecies variability regarding the effects on maize seed germination. On the average, the greatest germination reduction was found in seeds inoculated with the spore suspensions of F. sporotrichioides and F. graminearum. A similar reduction was detected in seeds inoculated with F. proliferatum and F. subglutinans. The effect of F. subglutinans on seed germination reduction was higher compared to the two latter species, while the effects of F. semitectum and F. equiseti were smallest. The majority of isolates were of moderate pathogenicity, while the lowest number of isolates was either very pathogenic (7) or apathogenic (10). Pathogenicity of the isolates originating from wheat grains was generally lower than the pathogenicity of isolates originating from maize kernels, with the exception of F. sporotrichioides.Razlike u patogenost 93 izolata sedam vrsta roda Fusarium (F. graminearum, F. verticillioides, F. proliferatum, F. subglutinans, F. sporotrichioides, F. semitectum i F. equiseti), poreklom iz zrna kukuruza (61) i pšenice (32), proučavane su na osnovu procenta klijavosti inokulisanog semena. Ispitivane vrste ispoljile su inter- i intraspecijsku varijabilnost u pogledu uticaja na klijavost semena kukuruza. U proseku, najveće smanjenje klijavosti je utvrđeno kod inokulacije semena suspenzijom spora F. sporotrichioides i F. graminearum, a zatim, približno isto, kod inokulacija semena pomoću F. proliferatum i F. subglutinans. F. verticillioides je, u poređenju sa ove dve poslednje vrste, značajnije uticala na smanjenje klijavosti semena, dok su najmanje uticale vrste F. semitectum i F. equiseti. Većina izolata je bila srednje patogenosti, a najmanji broj je bio jako patogen (7) ili apatogen (10). Izolati poreklom iz zrna pšenice bili su slabije patogenosti od izolata poreklom iz zrna kukuruza, sa izuzetkom F. sporotrichioides

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

Antioxidative response of tomato genotypes to late blight infection

Wild species are widely used as potential sources of resistance of tomato to late blight (LB) (causal agent Phytophthora infestans). The biochemical response of wild and cultivated tomato genotypes with different levels of resistance to P. infestans was assessed through the total phenolic and flavonoid content and antioxidative capacity. In total, six genotypes were included in the research - three cultivated tomato varieties and three wild species. The wild genotypes Solanum pimpinellifolium S 220 and Solanum habrochaites had a significantly lower infection rate compared to the other tested genotypes. After disease assessment on the leaves, biochemical analyses were performed. Grouping of the wild accessions according to principal component analysis (PCA) analysis indicated similar reaction to LB infection. Furthermore, late blight trait is closer to cultivated genotypes. Although the phenolics and flavonoids have high importance in the reaction of tomato plants to late blight infection, these traits are not closely related to wild species and the disease. According to this study, the antioxidative tests that indicate a response of wild species to late blight infection are total antioxidant activity (TAA), ferric-reducing antioxidant power (FRAP) and radical cation scavenging activity (ABTS)