Drechslera Oryzae Research Articles

Antagonistic potential of soil fungi as biocontrol agent against rice pathogens

Antagonistic potential of six soil fungi viz., Aspergillus flavus Link., A. fumigatus Fresen., A. niger Tiegh., Penicillium sp., Trichoderma harzianum Refat. and T. viride Pers. against eight pathogenic fungi viz., Alternaria alternata (Fr.) Keissler, Curvularia lunata (Wakker) Boedijn, Drechslera oryzae Breda de Haan (Subramanian and Jain), Fusarium moniliforme Sheldon, F. solani (Mart.) Sacc. Microdochium oryzae (Hashloka and Yokogi) Sam. and Hal., Pestalotiopsis guepinii (Desm.) Stay. and Sarocladium oryzae (Sawada) W. Gams and D. Hawks of rice were evaluated. In colony interaction, the highest growth inhibition (88%) was observed owing to T. harzianum against Alternaria alternata.Volatile substances from soil fungi inhibited the radial growth of the test pathogens which varied from 8.33 to 57.36%.The highest inhibition (57.36%) was found owing to T. harzianum against P. guepinii. The inhibition of mycelial growth of the test pathogens ranged from 29.05 to 64.5% owing to non volatile substances of the soil fungi. The highest mycelial growth inhibition was observed owing to T. harzianum against C. lunata. Trichoderma harzianum may be exploited commercially to control rice pathogens. Bangladesh J. Bot. 53(1): 101-108, 2024 (March)

Study on Major Disease-insect Incidence of Scented Gobindabhog Rice in New Alluvial Zone of West Bengal

A comprehensive study on “Improvement of production and storage system for Gobindabhog rice in West Bengal,” comprising two field and one laboratory experiment, was done at Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India, during the period of 2010–2012 to find out the optimum planting time, spacing, nutrients, disease, and pest management for scented Gobindabhog rice during the kharif season. Plant height, tiller production, and leaf area index increased consistently with the advancement of crop growth up to panicle exertion, panicle initiation (i.e., 56 DAT), and flowering (i.e., 84 DAT) stages, respectively. The planting date had a significant effect on the incidence of blast disease in Gobindabhog rice during both 2010 and 2011, except at 28 DAT. Delay in planting generally provided a favorable environment for the causal organism (Payricularia oryzae) during the vegetative and reproductive stages of Gobindabhog rice, thereby leading to a greater incidence of delayed crops (25 July, 10 August, and 25 August) than the earlier one (10 July). The susceptibility of the Gobindabhog rice crop to brown spot disease caused by Drechslera oryzae increased progressively with the advancement of crop age from 28 DAT (i.e., active tillering stage) to 84 DAT (i.e., flowering stage). The population of gundhi bug (Leptocorisa acuta) increased steadily from 84 DAT (i.e., 50% flowering) to 112 DAT (maturity stage), irrespective of main and sub-plot treatments as well as years of investigation.

Chemical characterization and antifungal potential of Trigonella foenum-graecum L. followed by molecular docking studies

The present study involves the chemical characterization and antifungal potential of fenugreek Trigonella foenum-graecum L. (fenugreek) seeds/leaves essential oils and their major constituents along with computational molecular docking calculations. The fenugreek seeds and leaves essential oils were extracted by hydro-distillation and characterized by Gas chromatography-mass spectrometry and Gas chromatography-flame ionization detector. Benzyl acetate (51.70%) and γ-tocopherol (42.09%), the major compounds in fenugreek seeds and leaves essential oils respectively were isolated by column chromatography. The essential oils and their major compounds were investigated for their antifungal activity against Rhizoctonia solani and Drechslera oryzae by the Poison food technique. Among all the treatments, fenugreek leaves essential oil was the most effective with ED50 values of 850 and 1120 ppm against R. solani and D. oryzae respectively. All the treatments were found more effective against R. solani than D. oryzae. Molecular docking studies of the major compounds present in the essential oils against R. solani agglutinin (PDB ID 4G9N and 4G9M) suggested that 9,19-cyclolanost-24-en-3-ol present in abundance in fenugreek leaves essential oil than the seeds essential oil bound effectively with the targeted protein with the docking score of -6.14 kcal mol−1. Overall, our combined experimental and computational study provides scientific justification for the use of fenugreek leaves essential oil as a natural antifungal agent against R. solani. Moreover, fenugreek leaves essential oil being most effective against D. oryzae may also be used as a natural antifungal agent against it.

Prevalence of Seed-Borne Fungi Associated With Selected Rice Varieties of Brri

Selected rice varieties such as BR-78, 80, 81, 82, 83, 84, 86, 87, 88 and 89 were used in this experiment to investigate the prevalence of seed-borne fungi. A total of twelve fungi belonging to six genera was isolated from the seeds of selected BRRI (Bangladesh Rice Research Institute) rice varieties by using tissue planting method. They were Alternaria alternata (Fr.) Keissler, Aspergillus flavus Link, A. fumigatus Fresenius, A. niger van Tieghem, A. ochraceous Wilhelm, A. terreus Thom, Curvularia lunaata (Wakker) Boedijn, Curvularia sp. 1, Drechslera oryzae Breda de Haan (Subramanian and Jain), Penicillium sp.1, Penicillium sp. 2 and Rhizopus stolonifera (Ehrenb.) Vuill., Among the isolated fungi A. niger was the most prevalent fungi associated with the seeds of the rice varieties with a mean per cent frequency of 16.93 and the least prevalent fungi was A. ochraceous with a mean per cent frequency of 0.27. Mean per cent frequency of A. niger (16.33) was highest which was followed by A. flavus (7.27), Penicillium sp.1 (5.93), Penicillium sp. 2 (3.27), Drechslera oryzae (2.67) and A. terreus (2.53). Among the identified seed-borne fungi Curvularia lunata and Drechslera oryzae were found as pathogenic and cause seed-borne diseases. J. Biodivers. Conserv. Bioresour. Manag. 2023, 9(1): 61-68

Effects of Soaking Rice Seeds with Biofertilizers on Brown Spot Disease Drechslera oryzae and Sprout Growth.

Rice (Oryza sativa L.) is a staple food crop for the majority of the population in Indonesia. In rice cultivation, brown spot disease is often damaged by the fungus Drechslera oryzae. This study aims to examine the effect of applying biofertilizers on brown spot disease and growth of rice sprouts. The treatments tried were Bion-up, KIBRT, Azoto-Tricho, biofertilizers and propineb fungicide as a comparison. The experimental design used a completely randomized design with four replications. The observed variables were disease intensity, shoot height, root length, and fresh weight of sprouts. The results showed that the application of biological fertilizers Bion up, KIBRT and Azoto-Tricho was effective in controlling brown spot disease and increasing growth in shoot height, root length and sprout fresh weight.

Efficacy of indigenous Trichoderma isolates of West Timor, Indonesia, as biocontrol agents of brown spot (Drechslera oryzae) on two upland rice varieties

BackgroundBrown spot disease is one of the most destructive foliar diseases of rice. Biological control of this disease is considered more environmentally safe, but the biological control agents have limited availability. The fungus Trichoderma can be used as a biocontrol agent for various plant diseases, including brown spots. Indigenous Trichoderma species from West Timor were evaluated in this study to reveal their effectiveness in reducing brown spot disease of upland rice. The study was conducted under a screen house condition using a factorial treatment design laid out in a completely randomized design. The two factors were the brown spot disease control method (T. viride, T. harzianum, T. hamatum, fungicide Trivia 73 WP, and a control treatment) and upland rice genotype (Inpago 7 and Breun Senaren 2).ResultsThe results showed that Trichoderma spp. and the fungicide Trivia 73 WP caused significantly lower AUDPC and apparent infection rate than the control treatment. The total phenol content and agronomic characters (number of reproductive tillers per plant, number of filled grains per panicle, grain yield per plant) were higher in the Trichoderma and fungicide treatments than the control treatment. Meanwhile, tannin and saponin levels were non-significantly different among treatments. Trichoderma and the fungicide Trivia treatments effectively suppressed brown spot disease of upland rice, and the efficacy was dependent on the rice variety, with a mean efficacy range over the two varieties of 27.05–36.42%. The Trichoderma and the fungicide Trivia treatments increased the grain yield per plant differentially in the 2 rice varieties, with a mean grain yield increase over the 2 varieties of 13.0% (T. viride), 23.5% (T. harzianum), 35.0% (T. hamatum), and 19.9% (Trivia 73 WP).ConclusionEfficacy of local Trichoderma of West Timor and the fungicide Trivia treatments were varietal dependent with T. hamatum being the most effective in reducing the brown spot disease and producing the highest grain yield increase over the 2 rice varieties. The local Trichoderma species of West Timor have a future potential as biocontrol agents of upland rice brown spot disease, but it is necessary to further evaluate their effectiveness against the disease in replicated field trials.

Chemical composition and molecular docking studies of Cyamopsis tetragonoloba (L.) Taub. leaves and fruits extracts as antifungal agents against rice phytopathogenic fungi

The present study investigates the chemical composition of Cyamopsis tetragonoloba (L.) Taub. leaves and fruits extracts and their molecular docking studies as antifungal agents against rice phytopathogenic fungi. The extracts were prepared by using Soxhlet apparatus taking ethyl acetate, ethanol and methanol as solvents. These extracts were characterized by GC-MS analysis and were evaluated for their antifungal potential against Rhizoctonia solani and Drechslera oryzae. Maximum antifungal activity was shown by ethyl acetate fruits extract with minimum EC50 values. All the major compounds in guar extracts were subjected to molecular docking studies against the fungal target protein, i.e. lanosterol 14α- demethylase to find their potential binding mode and binding affinity. Among the six compounds, stigmasterol and γ-sitosterol bound most strongly with the receptor through the involvement of single-residue interactions. Hence, both these sterols present in ethyl acetate fruits extract can be effectively used to control these phytopathogenic fungi.

Integrated Management of Seed Borne Pathogenic Fungi Of Brri 29 Rice Variety

A pot experiment was conducted with the single and combined doses of fungicides, plant extracts and antagonist for the management of nine rice pathogens. A total of 13 treatments including controls with or without inocula of the pathogen were tested. Amongst all the treatments only T6 (Bavistin + Azadirachta indica + Trichoderma harzianum) showed highest percentage of seed germination and seedling vigor index of seeds inoculated with Alternaria alternata , Aspergillus flavus, Curvularia lunata and Pestalotiopsis guepinii. Next to T6, T10 (Bavistin + Tall + Azadirachta indica + Citrus medica) showed promising result against Drechslera oryzae, Fusarium moniliforme, Microdochium oryzae and Sarocladium oryzae. T3 treatment (Azadirachta indica) showed highest percentage of seed germination and seedling vigor index in case of seeds inoculated with Fusarium solani. Amongst all treatments the integrated use of Bavistin, A. indica and T. harzianum showed the better performance for growth reduction of test pathogens and increased germination of seeds. Dhaka Univ. J. Biol. Sci. 31(1): 159-168, 2022 (January)

Integrated management of brown spot disease of rice

Brown spot of rice incited by Drechslera oryzae (Breda de Haan) Subramanian and Jain is the most important disease of rice. Regular occurence of disease and heavy yield losses caused by this disease in Bihar prompted us to undertake the studies. Seven chemicals were used for seed treatment and seven other fungicides were used for foliar spray against brown spot of rice. Seed treated with Bavistin recorded minimum disease severity (4.10%) and maximum yield (2.36 t/ha). Out of seven fungicides tested Antracol 75 WP (1.5 g/l) and RIL-FA 200SC (2.5 ml/l) reduced the disease severity and increased the yield. Among the bio-pesticides Tricure (5 ml/l), Biotos (2.5 ml/l) and Achook (5 ml/l) were found significantly effective in checking the brown spot severity and increasing the yield.

Mycoflora associated with diseased rice grains in Bangladesh and their pathogenic potentiality

Fifty six spotted rice grain samples of four commercially cultivated rice varieties namely BRRI 28, 29, Kalijira and Pajam were collected from 14 different districts of Bangladesh. Forty rice samples (Hybrid 2,3,4, BR7,11,12,14,16,22,23,25,26and BRRI28 to BRRI 55) were also collected from Bangladesh Rice Research Institute at Joydevpur. Twenty-fivespecies of fungi belonging to 15 genera were associated with these rice varieties. The isolated fungi were Alternaria alternata, Aspergillus clavatus, A. flavus, A. fumigatus, A.niger, A. ochraceus, A.oryzae, A. terreus, Chaetomium globosum, Cladosporium cladosporioides, Colletotrichum gloeosporioides, Curvularia lunata, C. lunata var. aeria, Drechslera oryzae, Fusarium moniliforme, F. oxysporum, F. solani, Microdochium oryzae, Nigrospora oryzae, Penicillium spp., Pestalotiopsis guepinii, Sarocladium oryzae and Trichoderma viride. Amongst these fungi nine i.e. Alternaria alternata (Fr.) Keissler, Aspergillus flavus Link, Curvularia lunata (Wakker) Boedijn, Drechsler aoryzae Breda de Haan (Subramanian and Jain), Fusarium moniliforme Sheldon, F. solani (Mart.) Sacc., Microdochium oryzae (Hashloka and Yokogi) Sam. and Hal., Pestalotiopsis guepinii (Desm.) Stay. and Sarocladium oryzae (Sawada) W. Gams and D. Hawks were found to be pathogenic to rice seeds. The most predominant fungus was D. oryzae which was followed by A. flavus and the least incidence was observed in case of F. solani and P. guepinni.
 Bioresearch Commu. 7(1): 932-940, 2021 (January)

Un nuevo agente de biocontrol de Drechslera oryzae


 El hongo patógeno del arroz Drechslera oryzae se inoculó en un mismo sustrato junto a Trichoderma harzianum en distintas condiciones medioambientales. Los mecanismos ejercidos por T. harzianum para antagonizar a D. oryzae y que en algunos casos actuaron sinérgicamente fueron: competencia por el espacio y los nutrientes, micoparasitismo y posible antibiosis. La capacidad antagonista de T. harzianum aumentó con los valores de temperatura y actividad del agua.

EFFECT OF ANGIOSPERMIC EPIPHYTES ON THE RELATIVE STATUS OF ERGOSTEROL AND ELECTROLYTE LEAKAGE IN FUNGAL PATHOGENS

Objective: In the present study, emphasis has been made to assay the antifungal activity of some angiospermic epiphytes like Cuscuta reflexa, Viscum orientale, Cymbidium bicolor, Bulbophyllum propinquum, Hoya ovalifolia and Dendrophthoe falcata.
 Methods: The antifungal activity due to epiphytes extracts was expressed in term of reduction in dry biomass of fungi based on the relationship of ergosterol content and electrolyte leakage in fungal pathogens viz., Colletotrichum dematium, Drechslera oryzae, Fusarium oxysporum and Fusarium solani treated with epiphytes extract.
 Results: Treated fungi showed increased in ergostesrol content and increased electrolyte leakage confirmed the pathetic situation of fungi; hence there was fungistatic effect, which was dose-dependent.
 Conclusion: The angiospermic epiphytes of selected species chosen for the study could be serves an alternative eco-friendly source to synthetic fungicides.

Effect of iron sulfide nanopriming in reducing Drechslera seed rot and seedling mortality in rice

Potential of sonochemically synthesized iron sulfide aqua dispersed nanoparticles (FeS-NFs) against Drechslera oryzae causing seed rot and seedling blight in rice was examined. Stable aqua dispersed nanoparticles of FeS were prepared in situ using ferrous sulfate heptahydrate (FeSO4. 7H2O) and sodium sulfide (Na2S) via sonochemical method. SEM graphs revealed the inhibition of spore formation in Drechslera oryzae at 17μg/ml, with much higher efficacy than the standard fungicide, captan. Rice seeds primed in FeS-NFs (30μg/ml) for 8 hours showed a significant reduction of 82.12% in seed rot and 76.08% in seedling blight which was far better than that controlled by captan (63.4% and 65.21%) and hydropriming (69.2% and 63.04%). The primed seeds showed maximum germination (90±2%) with longer shoot length (11.1±1.1cm) and vigorous seedlings without any symptoms of phytotoxicity. Utilization of FeS-NFs as eco-friendly water based antifungal seed priming agent (acting as both fungicide and nutrient) can provide better alternative to organic fungicides.

Evaluation of Bioactive Compounds of Some Common and Traditional MedicinalPlants in Relevance with the Growth of Paddy

India, in terms of its natural resources, is a very rich country since thousands of medicinal plants are found growing and can as well be accessed for their benefits. Manufacturing drugs using plant products has been a field of utmost importance these days. The therapeutic value behind such plants can be exposed to the world only if it is brought out in a consumable form. Assessing the phytochemistry of each plant before determining its medicinal property and the condition that it can target is crucial. Several phytochemical tests and bioassays are therefore necessary to evaluate the various chemical compounds in the plants. In this study, weeds viz., Leucas aspera (Lamiaceae), Tridax procumbens (Asteraceae), Justiciaadhathoda (Acanthaceae), Alternanthera sessilis (Amaranthaceae), Phyllanthus niruri (Euphorbiaceae), Acalypha indica (Euphorbiaceae) and six medicinal plants Rauvolfia tetraphylla (Apocynaceae), Achyranthes aspera (Amaranthaceae), Tinospora cordifolia (Menispermaceae), Bacopa monnieri (Scrophulariaceae), Eclipta prostrata (Asteraceae) and Clitoria ternatea (Fabaceae) were chosen to investigate their phytochemical composition, phenolic content, flavonoid content, anti-fungal activity and their effect on paddy seed germination. Extraction was carried out using methanol. The highest phenolic content was observed in extract of P. niruri (29.66mg/g GAE). In contrast Leucas aspera showed highest flavonoid content (12.76mg/g QAE). P. niruri at its higher concentration indicated the reduced incidence of fungi like Alternaria padwickii, Verticillium cinnabarinum and Drechslera oryzae which was from 9 to 2%, 5 to 2%, and 10 to 3%, respectively. These findings indicated the importance of common traditional plants in agriculture apart from their medicinal value.

EFFECT OF EPIPHYTES EXTRACT ON THE PEROXIDASE ACTIVITY IN THE CROP SEEDLINGS CHALLENGED WITH FUNGAL PATHOGENS

Objectives: The objective of the present study to test the angiospermic epiphytes such as Bulbophyllum propinquum and Dendrophthoe falcata for their effect against some pathogenic fungi of sorghum, paddy and chilli, through seed treatment and foliar spray in challenging with the infectivity of the pathogens.
 Methods: The plant extracts were carried out by the Soxhlet extraction method and culture of pathogenic fungi were cultured and maintained in vitro for further use. The peroxidase (POX) enzyme activity in the seedlings was measured spectrophotometrically at 300 nm and expressed as Δ optical density 300 nm/min/mg protein.
 Results: The results of this study indicated 92 and 98% seed germination in the control samples, respectively. In the chilli and paddy which were reduced to 64 and 58% in seedlings inoculated with Colletotrichum dematium, Drechslera oryzae, correspondingly. Similar observation was made in sorghum samples on treatment with Fusarium solani and Fusarium oxysporum, whose germination was drastically reduced to 74 and 69% compared to control (92%). In all the cases, seed treated with epiphytes extracts indicated the stimulated germination over pathogen inoculated samples. In parallel to this, the peroxidase assay also indicated its diminished/reduced activity in pathogen treated seedlings of the selected crop species. Seedlings of epiphytes extract treatment challenged with respective pathogens showed an increased activity over only pathogen treated samples.
 Conclusion: The results clearly indicated the influence of POX in early growing stages of the seedlings corresponds to 12–72 h of incubation in spite of pathogenic activity. Thus, it proved the loss of enzyme activity seedlings on pathogen infection. Contrastingly, POX activity in the seedlings irrespective of the crop species remained high during the early growth stages of the seedlings.

In vitro evaluation of fungicides and plant extracts against pathogenic fungi of two rice varieties

Five pathogenic fungi viz., Alternaria alternata (Fr.) Keissler, Curvularia lunata (Wakker) Boedijn, Drechslera oryzae Breda de Haan (Subramanian and Jain), Fusarium moniliforme Sheldon and Pestalotiopsis guepinii (Desm.) Stay. were isolated from two rice varieties viz., BRRI 29 (Boro) and Pajam (Aman) by Blotter and Tissue planting methods. Ten fungicides i.e. Bavistin 50 WP, Salcox 50 WP, Dithane M-45, Indofil M-45, Tall 25 EC, Ridomil MZ Gold, MC Sulphur 80, Greengel, Hayvit 80 WP and Capvit 50 WP at 100, 200, 300, 400 and 500 ppm were evaluated against the above mentioned five pathogenic fungi. Tall 25 EC completely inhibited the radial growth of the test fungi at all the concentrations except Fusarium moniliforme. Antifungal properties of ethanol extract of Artocarpus heterophyllus Lamk., Tagetes erecta L., Datura metel L., Senna alata (L.) Roxb., Azadirachta indica A. Juss., Citrus medica L., Mangifera indica L., Asparagus racemosus Willd., Nerium indicum Mill. and Allium sativum L. at 5, 10 and 20% concentrations were evaluated against the five test pathogens. All the plant extracts completely inhibited the radial growth of the test fungi at 20% concentration except Asparagus racemosus.

Plant pathogens and soil microbes associated with Citrus indica in Nokrek biosphere reserve of Meghalaya

Citrus indica Tanaka, commonly known as Wild Indian Orange, is the most primitive of all citrus fruits found around the world. This plant is found growing in the wild only in Nokrek Biosphere Reserve of Garo Hills, Meghalaya. The plant is of great significance among the local people for various traditional medicines and spiritual purposes. The objective of the study was to identify the disease causing pathogens and soil microbes inhabiting the rhizosphere of C. indica in the three zones of Nokrek Biosphere Reserve, as well as to assess the relationship between soil microbes and occurrence of plant pathogens. Nine diseases caused by fungal pathogens and one disease caused by algae were observed. Change in zone exerted a significant influence on occurrence of pathogens in C. indica. Occurrence of soil microbes in the rhizosphere of C. indica was significantly influenced by change in zone, soil depth and season. Soil microbes were found to be more in top soil than sub-soil. Among the identified soil microbes, Aspergillus flavus, Penicillium digitatum and Rhizopus nigricans were the dominant ones. At 0–15 cm soil depth, soil microbes Curvularia lunata, Drechslera oryzae and Aspergillus niger exerted positive influence on occurrence of plant pathogens Capnodium citri, Cephaleuros virescens, Alternaria citri and Mycoshaerella citri, while plant pathogens like Acrosporium tingitanium, Diaporthe citri, Penicillium digitatum and Phytophthora citrophthora were antagonistically affected. At 15–30 cm soil depth, soil microbe Drechslera oryzae positively influenced the occurrence of plant pathogens Alternaria citri and Cephaleuros virescens, while Colletotrichum falcatum at 15–30 cm soil depth positively influenced the occurrence of plant pathogens Acrosporium tingitanium and Diaporthe citri.

Synthesis and Antifungal Activity of Khusinol and its Derivatives

Khusinol isolated from vetiver oil was subjected to various chemical modifications. Ester derivatives of khusinol were prepared with acetic anhydride and benzoyl chloride. Epoxides of khusinol were synthesized using perbenzoic acid, vanadium oxyacetylacetonate–t-butyl hydroperoxide, and N-bromosuccinimide– sodium hydroxide. All the compounds showed promising in vitro antifungal potential against Alternaria triticina, Drechslera oryzae, and Fusarium moniliforme with ED50 values in the range of 200–250 μg/mL.

Chemical Composition and Antimicrobial Activity of Origanum vulgare subsp. viride Essential Oils Cultivated in Two Different Regions of Iran

The objective of this research was to examination the chemical compounds and antimicrobial activity of domesticated Origanum vulgare subsp. viride essential oils from Mashhad and Yazd, Iran. GC and GC-MS analysis revealed that the essential oils of Mashhad andYazd samples predominantly contain thymol (20.97-21.6 %), 4-terpineol (16.27-15.85 %), γ-terpinene (7.62-5.46 %), trans-sabinene hydrate (6.11-7.91 %) and p-cymene (4.27-5.69 %). The variations observed between the essential oil compositions were mostly quantitative but also qualitative. The inhibitory effects of the essential oils were tested against 10 phytopathogenic microorganisms, including Xanthomonas citri, Ralstonia solanacearum, Erwinia amylovora, Pectobacterium carotovorum, Xanthomonas oryzae bacteria and Bipolaris sorokiniana, Fusarium oxysporum, Drechslera oryzae, Alternaria alternata and Stemphylium sarciniforne fungi. The antimicrobial test results indicated that the essential oils had antibacterial and antifungal activities against all of the tested microorganisms. According to the width of the inhibition zone X. citri was the most sensitive bacterium to the essential oils with MIC (3.5 μgmL-1) and MBC (5 μgmL-1) in both samples. The most sensitive fungus was D. oryzae with 1 and 0.8 μgmL-1 in Mashhad and Yazd essential oil samples. Also the most susceptible fungi with MIC 2.1 μgmL-1 were B. sorokiniana in essential oil obtained from Mashhad and S. sarciniforne with MIC 2.2 μgmL-1 in the essential oil of Yazd’s sample. In conclusion, due to the antimicrobial activities of O. vulgare subsp. viride essential oil, the effectiveness of essential oils against serious plant pathogens is considerable. In this way, the essential oil has a good capacity as an alternative to synthetic products in various industries.

Prevalence of Fungi With Seeds of Twenty Brri Released Rice Varieties and Seed Quality Analysis

A total of 20 rice varieties of BRRI dhan 56 to BRRI dhan 75 were collected from Bangladesh Rice Research Institute (BRRI) for seed quality analysis, detection and identification of fungi associated with seeds of selected rice varieties. Dry inspection indicated that the percentage of pure seeds ranged from 90 - 100. The highest percentage of pure seed was found in BRRI dhan 66 and BRRI dhan 70 (100) and lowest in BRRI dhan 68 (90). A total of 21 fungal species were isolated from the selected rice varieties following “Blotter and Tissue Planting” methods. They were Alternaria padwickii, A. tenuissima, Aspergillus flavus, A. fumigatus, A. niger, A. ochraceus, A. clavatus, A. terreus, Bipolaris sorokiniana, B. spicifera, Chaetomium globosum, Curvularia lunata, Drechslera oryzae, Fusarium sp.1, Fusarium sp. 2, Nigrospora sp., Penicillium sp., Pestalotiopsis guepinii, Rhizopus stolonifer, Syncephalastrum racemosum and Trichoderma viride. Among them Penicillium sp., Drechslera oryzae, Aspergillus ochraceus, A. flavus, A. fumigatus, A. niger and Fusarium sp.1 were predominant in most of the rice varieties. In Tissue Planting method Drechslera oryzae showed the highest mean per cent frequency (6.69) and lowest was in the Bipolaris sorokiniana (0.41). Maximum total fungal association was recorded in variety BRRI dhan 61 (156.79%) and minimum in BRRI dhan 66 (24.69%). In Blotter method Penicillium sp. showed the highest mean per cent frequency (7.56) and lowest was in Rhizopus stolonifer (1.71). Maximum total fungal association was recorded in BRRI dhan 63 (147.37%) and minimum in BRRI dhan 65 (19.21%). Germination percentage of seeds was highest in BRRI dhan 66 (88) followed by BRRI dhan 67 (82), BRRI dhan 74 (80) and lowest in BRRI dhan69 (24). The percentage of seedling mortality was highest in BRRI dhan 63 (42) and lowest in BRRI dhan 74 (8.0) followed by BRRI dhan 67 (10). Correlation coefficient and regression analysis indicated that prevalence of fungi has significant effect on seed germination and seedling mortality. The present research work suggests that out of 20 BRRI rice varieties, BRRI dhan 65, BRRI dhan 66, BRRI dhan 67 and BRRI dhan 74 showed better performances on the basis of percentage of pure seed, fungal association, seed germination and seedling mortality.
 Asiat. Soc. Bangladesh, Sci. 44(1): 79-89, June 2018