Biofungicidal activity of nanosilica for inhibition of seed-borne diseases in maize grains

Mycotoxin-producing molds which considered as common maize grains contaminants are the genera Fusarium, Aspergillus and Penicillium. There are natural and safe ways to protect grains from mold contamination as the use of essential oils and chemical treatments. A total number of 25 samples were used to study the natural frequency in five governorates in Egypt, Molecular identification indicated that the most frequent fungi were Fusarium verticillioides, Aspergillus niger, Talaromyces verruculosus, Aspergillus flavus and Aspergillus terreus. The in vitro studies have been done to determine mycelial growth and spore germination inhibition of the two A. flavus; isolated and reference isolates. Thyme and acetic acid were tested in direct contact assay to study their effects on mycelial growth. Treatments showed significant impact on mycelial growth and spore germination inhibition of both A. flavus isolates. In the postharvest application treatments: as vapour and carrier contact assay, Thyme and Acetic acid were tested to determine their influence on growth and aflatoxin production in A. flavus isolates by liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS). Results indicated that both treatments were effective in inhibition of aflatoxin production in both vapour and carrier assays as they succeeded in reducing AFB1 while they inhibited completely the production of AFB2. The extent of the inhibition of aflatoxin production was dependent on the concentration and storage duration of treatments applied.

Studies of the biodiversity of plant pathogenic and toxigenic fungi are attracting great attention to improve the predictability of their epidemics and the development of their control programs. Two hundred maize grain samples were gathered from 25 maize-growing governorates in Egypt and 189 samples were processed for the isolation and identification of seed-borne fungal microbiome. Twenty-six fungal genera comprising 42 species were identified according to their morphological characteristics and ITS DNA sequence analysis. Occurrence and biodiversity indicators of these fungal species were calculated. Ustilago maydis, Alternaria alternata, Aspergillus flavus, A. niger, Penicillium spp., Cladosporium spp. and Fusarium verticillioides were the highly frequent (>90% for each), recording the highest relative abundance (˃50%). Al-Menia governorate showed the highest species diversity and richness, followed by Sohag, Al-Nobaria and New Valley governorates. Correlations of 18 fungal species with temperature, relative humidity, precipitation, wind speed, and solar radiation were analyzed using canonical correspondence analysis. Results showed that relative humidity, temperature, and wind speed, respectively, were the most impactful weather variables. However, the occurrence and distribution of these fungi were not clearly grouped into the distinctive climatic regions in which maize crops are grown. Monitoring the occurrence and distribution of the fungal pathogens of maize grains in Egypt will play an important role in predicting their outbreaks and developing appropriate future management strategies. The findings in this study may be useful to other maize-growing countries that have similar climatic conditions.

Increasing Se concentration in maize grain with soil- or foliar-applied selenite on the Loess Plateau in China

Mycoflora of maize (Zea mays L.) grain (Variety: Bako Hybrid-660) stored in two traditional storage containers (Gombisa and Sacks) for 180 days was studied for mycoflora in two agro-ecologies, that is Intermediate and Lowland, with altitude ranges of 1500-2500 meters above sea level, and 1000-1500 meters above sea level, respectively, in Jimma zone, Ethiopia. The temperature and relative humidity were observed for identifying fungi species which can flourish and cause maximum deterioration to maize grains. Significant (P<0.05) decreases in germination rate of the grains were observed with time under each storage method for both the low and intermediate altitude ranges. Germination percentage reduced from 98% and 97.5% to 68.5% and 80.5% for grains stored in Gombisa and Sacks, respectively. Storage type significantly (p<0.05) affected seed germination under intermediate agro-ecology whereas no significant (p>0.05) effect was observed under lowland agro-ecology due to storage container type. One sterile white mycelium and a total number of eight species of fungi viz., Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Aspergillus tereus, Cladosporium cladosporioides, Drechslera halodes, Fusarium oxysporum and Penicillium chrysogenum were identified from maize grain at the beginning and during storage. The most common fungi recorded from both agroecologies in the two storage structures were A. flavus, A. niger, D. halodes and F.oxysporum. These fungi were recorded from 90, 51, 72 and 44 percentage of the seed samples, respectively. In the districts of both intermediate and lowland agro-ecology these fungi were consistently recorded throughout 180 days, during storage. A. fumigatus was detected in3.6% of samples while C. cladosporioides observed in 15% of the samples. Fungal species A. tereus and Penicillium were recorded in 0.5% of samples in selected districts of Jimma. These fungal species were known to cause deterioration of maize and are a health risk to humans and animals due to the toxins they potentially produce.

Quantifying maize grain yield losses caused by climate change based on extensive field data across China

A research study was conducted to identify and characterise seed-borne fungal pathogens associated with maize (Zea mays L.) in storage. Seed-borne fungal pathogenic infections of maize were studied using seed samples collected from Gokwe South District in Zimbabwe. The agar plating method using PDA medium was used to detect fungal pathogens on the maize seeds. A total of 150 treatments were used for this experiment, which were replicated three times in a randomised complete block design (RCBD). Analysis of the grain showed the presence of Fusarium moniliforme, Rhizopus stolonifer, Penicillium citrinum, and mostly Aspergillus species, namely, Aspergillus flavus, Aspergillus parasiticus, Aspergillus niger, and Aspergillus tamarii. Significant differences (p < 0.05) between treatments were detected for the pathogens. A total of ten samples were used for mycotoxin determination, and all of them were 100% positive with aflatoxin total, zearalenone, fumonisin, and deoxynivalenol (DON) having an average of 0.255 ppb, 2.425 ppb, 2.65 ppb, and 0.07 ppb, respectively. The present study showed that most grain samples are contaminated with different species of fungi with mycotoxigenic potential. The data on the diversity and magnitude of pathogen infection by fungal species will have a significant effect even at the regional level for predicting the extent of pre- and postinfections. Measures to reduce mycotoxin contamination are needed for maize grains.

The study was carried out to determine the microbes of maize grains sourced from five markets in Akungba and Ikare-Akoko, Ondo State, Nigeria. Bacterial and fungal microbes from roots of two maize cultivars DMR-LSR-Y and TZMSR-W were also investigated using the pour plate method. Results showed that grains from Oja Oba had the highest bacterial population of 4.8 × 105 cfu/g, while, the highest fungal load of 4.1 × 103 cfu/g was obtained from Osele market in Ikare. The two maize cultivars showed generally a low fungal count compared to their bacterial counterparts with 1.1 × 105 cfu/g root for a cultivar DMR-LSR-Y and 0.2 × 105 cfu/g root for TZMSR-W. The dry white maize grains showed generally low bacterial and fungal colonizations of 0.2 × 105 and 0.3 × 103 cfu/g respectively when compared to dry and fresh yellow types. Eleven bacteria genera and eight fungal species were isolated and identified from the roots and grains of maize. These includeCellulomonas, Bacillus, Pseudomonas, Staphylococcus, Micrococcus, Pediococcus, Microbacterium, Azospirillum, Kurtia, and Enterobacter, Acremonium zeae, Alternaria alternata, Aspergillus flavus, Aspergillus niger, Colletotrichum graminicola, Fusarium verticillioides, Saccharomyces cerevisiae, and Trichoderma koningii. The study was important in bioprospecting for biological activities and plant growth enhancers. Key words: Bacterial population, fungal population, endophytes, grains, roots, maize.

Maize grain is the second most vital food after wheat to humans and forms an important part of a human diet due to its nutrients. In Kenya, it is estimated that one out of every two acres of land put to crop production is under maize crop. Maize can also be fed whole to livestock (grazed or chopped and ensiled). Due to increased demand and the need for higher productivity, farmers have adopted modern farming methods which include use of fertilizers, pesticides, compost manure, and irrigation. Uses of these products elevate amounts of heavy metals in the soil. Such heavy metals such as lead (Pb) and cadmium when taken up by plants accumulate in the plants becoming toxic at high levels. It is essential to monitor these levels in grains and leaves to ensure they do not exceed the WHO permissible limits. This study aimed at monitoring the levels of heavy metals uptake in maize (Zea mays) grains and leaves is within permissible levels. Level of heavy metals in maize grains from different ecological zones in UG County had mean concentration of Zn 0.122, Cd 0.03, Cu 0.111, Co 0.04, and Pb 0.33 mg/kg. These results were below WHO standards except for Cadmium, Co, and Pb which were slightly higher than recommended standard. The study also found that maize leaves had mean concentration of Zn 0.115, Cd 0.04, Cu 0.117, Co. 0.041 and Pb 0.323 mg/kg. The results were below WHO standards except Co and Pb which had slightly higher levels than the recommended WHO standards. The analytical results from this study provided important baseline statistics on the concentration of selected heavy metals in maize grains and leaves besides being an important assessment of environmental pollution in rural areas where maize farming is predominant.

Antibiotics have revolutionized life saving medicine by providing cure for many number of life threatening diseases in human history, unexpectedly, many pathogenic microorganisms have developed resistant towards current antibiotic and this trend has become more and more serious. Hence the present study has been aimed to find out new marine derived antibiotic from Prosobranch mollusc Purpura persica. The whole body crude extract of methanol was partially purified by normal phase silica gel 160-120 mesh (Glaxo, Bombay) column chromatography with low polar to high polar solvent Hexane: Chloroform (F1); Chloroform (F2); Benzene (F3); Benzene: Methanol (F4), and Methanol F5). The antimicrobial activity of crude and eluted fractions were assayed against ten bacterial pathogens viz Aeromonas hydrophila, Bacillus cereus, Escherichia coli, Pseudomonas aerogenosa, Salmnella typhi, Shigella flexneri, Vibrio cholera 0139, Vibrio cholera classical, Vibrio cholerae 01790 and Vibrio cholerae EITOR and nine fungal pathogens viz. Aspergillus flavus, Aspergillus terreus, Aspergillus niger, Aspergillus fumigatus, Fusarium moniliforme, Trichoderma sp. Penicillium citrinum, Penicillium oxallicum and Rhizopus sp. respectively using the agar disc diffusion method. To find out the most probable antibiotic compound HPLC and GC-MS studies were carried out. Among the tested bacterial pathogens S. typhi, P. aerogenosa, S. flexneri and B. cereus and fungal pathogens A. fumigatus, A. terreus, F. moniliforme and Trichoderma sp. showed inhibition in growth by crude, F2, F3 and F5 fractions of P. persica respectively. The GC-MS and HPLC analysis revealed the presence chloridate cholest-5-en-3-01(3a) - carbano chloridate, a chloride compound 9, 12-octadecadienoyn chloride (z, z), and a cholest-5-en-3-ol(3)-carbonochloridate, eugenol, dibutyl phthalate, 1,2-Benzenedicarboxylic acid, diisooctyl ester and Phthalic acid, bis (7-methyloctyl) ester, and a steroid cholest-5-ene, 3-bromo-(3a), 2-piperidinone a monoterpene azulene, a fluro compound acetic acid, tri fluro- tetradecyl which were responsible for inhibiting the growth of microbes tested and the present test organism P. persica have great potential for developing useful drugs.

Biocontrol activity of the marine yeast Debaryomyces hansenii against phytopathogenic fungi and its ability to inhibit mycotoxins production in maize grain (Zea mays L.)

In Kenya, maize remains an important staple food in every household. Unfortunately, the fungus Aspergillus flavus can infect the maize and produce aflatoxins. While government efforts to remove contaminated maize from circulation are well intentioned, there remain concerns that consumers are still being inadvertently exposed to aflatoxin. The aim of this study was to sample maize in different parts of Kenya and determine if consumers were inadvertently being chronically exposed to aflatoxins. Seventy-five maize samples and 27 samples of maize flour from three regions of Kenya (Nairobi, Eastern and Western) were analysed using an ELISA assay followed by microtiter plate reader (Neogen model) where the optical density of each microwell was read using a 450nm filter. There was a significant difference in aflatoxin levels in maize grains between the three regions and five stores (P 0.05) at 95% confidence interval. Aflatoxin in maize flours were slightly above international upper limit of 5ppb but all the results were lower than the Kenya standard whose upper limit is 10ppb, indicating good manufacturing practices (GMP) by the millers. Samples of maize flours from Eastern Kenya had the highest aflatoxins concentrations at 6.98± 0.53 ppb. In summary, the study found aflatoxin contamination in maize grains especially in Eastern Kenya. The study concluded that measures put in place by government agencies for millers appear to be working. However, samples of maize grains showed variation among the regions and between stores, perhaps due to storage practices, with some levels far exceeding health limits. Due to higher levels of aflatoxin contamination in maize grains in relation to maize flours, the government and relevant stakeholders need to establish further measures to protect consumers. Key words: Maize grains, maize meal, aflatoxin, aflatoxicosis, maize consumption, Aspergillus flavus Key words : Maize grains, maize meal, aflatoxin, aflatoxicosis, maize consumption, Aspergillus flavus

A survey of pre-harvest ear rot diseases of maize and associated mycotoxins in south and central Zambia

Core IdeasN–P–K fertilizer microdosing increased maize yields by 99% in the humid forest zone.Gleyic Plinthic Acrisol produced higher maize grain yield than the Plinthic Acrisol.Microdosing increased N, P, and K use efficiency of maize in rotation vs. sole cropping.Maize grain yield and net returns were optimal with N20P40K20and N0P40K20microdoses.High fertilizer costs pose a challenge in smallholder farming; optimizing fertilizer recommendations that are affordable to resource‐poor farmers could increase crop yield and income. The study aimed to determining the yield and economic effects of N–P–K fertilizer microdosing on maize (Zea maysL.) crops on Gleyic Plinthic Acrisol (GPA) and Plinthic Acrisol (PA) in the semideciduous rainforest zone of Ghana using a split‐plot randomized complete block design with three replications. The field trial included two cropping systems (continuous maize cropping [CMC] and cowpea [Vigna unguiculata(L.) Walp.]–maize rotation [CMR]) as main plots with four treatments (N0P0K0, N0P20K20,N0P40K20, and N20P40K20) and the recommended fertilizer rate (N90P60K60) as subplots. Fertilizer treatment effects on maize stover and grain yields were assessed. The microdose treatments increased maize yields by 32 to 99% across cropping systems and soil types. Maize grain yield increase was higher on the GPA than on the PA. The N90P60K60and N20P40K20treatments resulted in higher grain and stover yields than the other treatments across cropping systems and soil types. Among the treatments maximum grain yield increases of 76 and 99% were obtained with N20P40K20on the PA and the GPA, respectively, under CMC. Under CMR, grain yield increased by 46% with N0P40K20(PA) and 74% with N0P20K20(GPA). The largest net return was obtained with N20P40K20under CMC across both soil types and with N0P20K20(GPA) and N0P40K20(PA) under CMR. These fertilizer microdoses can be considered appropriate for increasing maize yield and the income of smallholder farmers.

Integration of tropical forage legumes into cropping systems may improve subsequent crop nitrogen (N) supply, but removal of legume biomass for forage is likely to diminish these benefits. This study aimed to determine: (i) under irrigated conditions, the potential N inputs that can be provided by different tropical forage legumes to a subsequent cereal crop; and (ii) the residual N benefits once fodder had been removed. Available soil mineral N following tropical forage legumes lablab (Lablab purpureus), centro (Centrosema pascuorum), butterfly pea (Clitoria ternatea) and burgundy bean (Macroptilium bracteatum) and grain legume soybean (Glycine max) was compared with a maize (Zea mays) control when legume biomass was retained or cut and removed (phase 1). An oat (Avena sativa) cover crop was then grown to ensure consistent soil-water across treatments (phase 2), followed by a maize grain crop (phase 3) in which N uptake, biomass production and grain yield were compared among the phase 1 treatments. To determine N-fertiliser equivalence values for subsequent maize crop yields, different rates of fertiliser (0–150 kg urea-N/ha) were applied in phase 3. Retained biomass of butterfly pea, centro and lablab increased phase 3 unfertilised maize grain yield by 6–8 t/ha and N uptake by 95–200 kg N/ha compared with a previous cereal crop, contributing the equivalent of 100–150 kg urea-N/ha. When legume biomass was cut and removed, grain yield in the phase 3 maize crop did not increase significantly. When butterfly pea, centro and lablab biomass was retained rather than removed, the maize accumulated an additional 80–132 kg N/ha. After fodder removal, centro was the only legume that provided N benefits to the phase 3 maize crop (equivalent of 33 kg urea-N/ha). Burgundy bean did not increase subsequent crop production when biomass was either retained or removed. The study found that a range of tropical forage legumes could contribute large amounts of N to subsequent crops, potentially tripling maize grain yield. However, when these legumes were cut and removed, the benefits were greatly diminished and the legumes provided little residual N benefit to a subsequent crop. Given the large N trade-offs between retaining and removing legume biomass, quantification of N inputs under livestock grazing or when greater residual biomass is retained may provide an alternative to achieving dual soil N–fodder benefits.

This study was performed to investigate the effect of foliar spray by each of urea, boron, zinc, potassium alone and/or mixed of each with urea on maize ears and grains rot disease development, observe the chemical composition, phenolic compounds, antioxidant activity (DPPH), trypsin and α- amylase inhibitors activity of different treatments of maize grains. As well as, evaluate the sensory properties of balady bread prepared using different levels of corn flour and Gum Arabic as substitution of wheat flour. Moreover, the quality characteristic of dough. In vitro treatment of urea alone and/or its mixture with each of boron, zinc and potasium significantly reduced radial growth and sporulation of Fusarium moniliforme fungus on PDA medium followed by each of boron and zinc alone. While potassium was not effective in this respect compared to control. The effect of foliar nutrients applied on maize ears and grains rot disease was quantified and possible modes of action during field conditions. Twice applications at 50 and 65 days from planting by mixture of urea and boron; urea and zinc; urea and potassium were more effective than the treatment with each of urea, boron, zinc and potassium alone, provided the least disease and consistently better of yield and 100 grain weight. The effect of nutrients were really extended to reduce associated maize grains fungi infection, especially the main causal pathogen for ears and grains rot caused by F. moniliforme compared to control. Significantly difference between nutrients and application dates were found.Quality of maize grains treated with different nutrients were investigated. Results showed that,twice application of boron alone and mixture of urea and zinc produced maize grains contained the highest contents of crud protein (10.60 and 10.40%, respectively) while the lowest value of crud protein was 9.35% for treatment with urea and boron mixture applied twice. On the other hand, maize grains treatment with mixture of urea and zinc applied twice contain the highest content of total polyphenols extracted which was (320 mg GAE/100g) followed by mixture of urea and boron applied twice which recorded (305 mg GAE/100g), while the lowest value of total polyphenols extracted was (215 mg GAE /100g) for control maize grains. Furthermore, maize grains treated with mixture of urea and zinc applied twice contain the highest content of antioxidant activity (DPPH) (89.10%); trypsin inhibitor activity (T1A), (0.51 IU/mg) and α-amylase inhibitors (12.75 AIU/g) compared with control maize grains. Furthermore, the farinograph results indicated that, arrival time (min), developing time (min), dough stability (min) and weakening value (B.U) increased, while water absorption (%) decreased with increasing the level of adding corn flours and Gum Arabic when compared with wheat flour control.