scholarly journals Virulensi Isolat Fusarium oxysporum f. sp. cubense VCG 01213/16 pada Pisang Barangan dari Varietas Pisang dan Lokasi yang Berbeda

2016 ◽  
Vol 21 (2) ◽  
pp. 145
Author(s):  
Jumjunidang ◽  
Catur Hermanto ◽  
Riska
Keyword(s):  
Fusarium Oxysporum ◽  
Incubation Period ◽  
Disease Severity ◽  
Control Method ◽  
Block Design ◽  
Severity Index ◽  
Disease Severity Index ◽  
Tropical Fruit ◽  
Randomized Block Design ◽  
Tissue Culture Propagation

Analisis genetik  isolat-isolat  cendawan Fusarium  oxysporum f. sp. cubense (Foc) VCG 01213/16 penyebab penyakit layu pada tanaman pisang menunjukkan adanya keragaman yang nyata. Penelitian bertujuan mempelajari keragaman virulensi isolat-isolat yang terkelompok dalam VCG 01213/16, berasal dari berbagai daerah dan varietas pisang yang berbeda.  Penelitian dilakukan di Laboratorium Penyakit dan Rumah Kasa Balai Penelitian Tanaman Buah Tropika (Balitbu Tropika) Solok, dari bulan Maret sampai dengan Juni 2009. Rancangan yang digunakan ialah acak kelompok dengan 10 perlakuan dan tiga ulangan, masing-masing perlakuan terdiri atas 10 tanaman. Perlakuan terdiri atas 10 isolat Foc VCG 01213/16 yang berasal dari varietas pisang dan lokasi berbeda. Tanaman uji ialah benih pisang Barangan hasil perbanyakan kultur jaringan. Hasil penelitian menunjukkan bahwa terdapat keragaman virulensi 10 isolat Foc VCG 01213/16 yang dinilai dari perbedaan masa inkubasi, persentase serangan, dan indeks keparahan penyakit pada bonggol dan daun pisang Barangan. Sembilan isolat Foc yang diuji mempunyai virulensi yang tinggi. Masa inkubasi berkisar antara 13,98 dan 16,80 hari, persentase serangan 93,33-100%, dan indeks keparahan penyakit pada bonggol dan daun masing-masing berkisar 3,46-5,35 dan 4,68-5,41. Isolat Foc VCG 01213/16 yang berasal dari Jabung-Lampung Timur dan diisolasi dari pisang varietas Ambon Kuning (isolat F) menunjukkan virulensi yang relatif lebih rendah dibanding sembilan isolat  Foc lainnya dengan masa inkubasi 30,27 hari, indeks keparahan penyakit pada bonggol dan daun masing-masing sebesar 2,14 dan 3,76.  Hasil penelitian ini bermanfaat dalam memberikan informasi tentang biologi F. oxysporum f. sp. cubense sebagai dasar untuk penyusunan teknik pengendalian yang tepat.<br /><br /><br />Genetic analysis of isolates of the Fusarium oxysporum f. sp. cubense (Foc) that are grouped in VCG 01213/16, as the causal agent of wilt disease in banana plants showed a considerable variation. This research aimed to study the variation in virulence of isolates that are grouped in VCG 01213/16 from different varieties of banana and regions. The study was conducted in the Protection Laboratory and the Screenhouse of Indonesian Tropical Fruit Research Institute (ITFRI) Solok, from March to June 2009. A randomized block design was used in this research with 10 treatments and three replications. Each treatments consisted of 10 banana plants. The treatment was 10 Foc isolates belonging to VCG 01213/16 originating from different varieties of banana and locations. Barangan plantlets produced from tissue culture propagation were used as the planting material. The results showed that there were high variations in virulence among 10 Foc isolates in VCG 01213/16 based on variables of the incubation period, percentage of wilt, and disease severity index on corm and leaves of Barangan variety. Nine of the 10 Foc isolates tested were highly virulent isolates. The incubation period ranged from 13.98 to 16.80 days, the percentage of wilt from 93.33 to 100%, and the disease severity index of corm and leaves ranged from 3.46 to 5.35 and from 4.68 to 5.41, respectively. The Foc VCG 01213/16 isolates originated from Jabung, East Lampung and from Ambon Kuning variety (isolate F) shown relatively low virulence than others isolates that the incubation period was 30.27 days and the disease severity index on the corm and leaves was 2.14 and 3.76, respectively. This result provides useful information on biology of F. oxysprum f. sp. cubense to find out the best control method of the pathogen.<br /><br />

scholarly journals Greenhouse Cucumber Cultivars Differ in Susceptibility to Fusarium Root and Stem Rot

2004 ◽  
Vol 14 (2) ◽  
pp. 240-242 ◽  
Author(s):  
Steve Rose ◽  
Zamir K. Punja
Keyword(s):  
Fusarium Oxysporum ◽  
Disease Severity ◽  
Severity Index ◽  
Stem Rot ◽  
Disease Severity Index ◽  
Plant Mortality ◽  
Breeding Lines ◽  
The Third ◽  
Enhanced Resistance ◽  
Greenhouse Cucumber

Eighteen cucumber (Cucumis sativus L.) cultivars (long English type) were screened for their susceptibility to fusarium root and stem rot caused by Fusarium oxysporum Schlechtend.: Fr. f.sp. radicis-cucumerinum D.J. Vakalounakis using seedlings at the third true-leaf stage. Roots were trimmed and dipped into a spore suspension (105 spores/mL) of the pathogen and the plants were re-potted. A disease severity index (DSI) was used to assess disease responses 4 or 8 weeks later based on plant mortality and the height of surviving plants compared to the noninoculated controls. `Sienna', `Amazing' and `Dominica' were most susceptible to infection and the resulting DSI values were significantly (P ≤ 0.05) higher compared to noninoculated control plants. The cultivars `Korinda', `Euphoria' and `Aviance' displayed significantly lower DSI values which were not significantly different from noninoculated control plants. The remaining 12 cultivars displayed DSI values which were intermediate between the above two classes of responses. The results from this study indicate there is the potential to identify and develop cultivars and breeding lines of greenhouse cucumbers with enhanced resistance to fusarium root and stem rot.

scholarly journals Pemanfaatan Tumbuhan Penghasil Minyak Atsiri untuk Pengendalian Fusarium oxysporum f. sp. cubense Penyebab Penyakit Layu Fusarium pada Tanaman Pisang

2011 ◽  
Vol 21 (4) ◽  
pp. 331
Author(s):  
Riska ◽  
Jumjunidang ◽  
Catur Hermanto
Keyword(s):  
Essential Oils ◽  
Fusarium Oxysporum ◽  
Incubation Period ◽  
Fusarium Wilt ◽  
Block Design ◽  
Control Treatment ◽  
Initial Number ◽  
Combination Treatments ◽  
Lemon Grass ◽  
Randomized Block Design

Penyakit layu yang disebabkan oleh cendawan Fusarium  oxysporum f. sp. cubense (Foc) merupakan salah satu penyakit penting pada tanaman pisang. Teknik pengendalian yang efektif dan berwawasan lingkungan perlu terus diupayakan, di antaranya melalui penggunaan pestisida nabati. Penelitian ini bertujuan mengetahui pengaruh pemberian daun beberapa tumbuhan penghasil minyak atsiri terhadap jumlah propagul awal Foc dalam tanah dan pengendalian penyakit layu Fusarium pisang pada skala rumah kasa. Penelitian dilakukan di Laboratorium Penyakit dan Rumah Kasa Balai Penelitian Tanaman Buah Tropika Solok mulai bulan Februari sampai dengan Juni 2009. Rancangan yang digunakan dalam percobaan ialah acak kelompok dengan lima perlakuan dan empat ulangan, masing-masing ulangan terdiri atas lima tanaman. Perlakuan tersebut adalah empat jenis daun tumbuhan penghasil minyak atsiri yaitu : (A) daun nilam, (B) serai, (C) daun kayu manis, (D) daun cengkeh, dan (E) tanpa perlakuan (kontrol). Tanaman uji adalah bibit pisang Ambon Hijau hasil perbanyakan kultur jaringan umur 2  bulan setelah aklimatisasi. Hasil penelitian menunjukkan bahwa pemberian daun tumbuhan penghasil minyak atsiri mampu menekan jumlah propagul awal Foc di dalam media tanam. Persentase penurunan propagul Foc awal dalam media yang berumur 5 minggu setelah pemberian tumbuhan penghasil minyak atsiri berkisar antara 50,1-70,6%. Semua perlakuan, kecuali daun nilam, juga mampu memperlambat munculnya gejala atau masa inkubasi penyakit. Masa inkubasi penyakit paling lama terjadi pada perlakuan pemberian daun cengkeh, diikuti dengan perlakuan pemberian daun kayu manis dan daun serai dengan perpanjangan masa inkubasi masing-masing sampai 22 dan 15 hari dibandingkan dengan kontrol. Pemberian daun tumbuhan mengandung minyak atsiri belum berakibat pada penurunan persentase dan intensitas serangan penyakit, sehingga perlakuan pemberian tumbuhan penghasil minyak atsiri perlu dikombinasikan dengan metode pengendalian lain agar lebih efektif dalam menekan penyakit layu Fusarium.<br /><br /><br /><br />Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is the most important disease on banana. Effective and environmental friendly techniques in controlling the disease need to be effort continually, among of them are with application of biopesticide to suppres Foc. The objectives of the research were to know the effect of some plant producing essential oils on initial number of propagule of Foc in soil and disease development of Fusarium wilt of banana. The research was conducted at Indonesian Tropical Fruits Research Institute Solok from February to June 2009. A randomized block design with five treatments and four replications was used, whereas each treatment consisted of five plants. Four types of plant producing essential oils as treatments, namely (A) crude of patchouly leaves, (B) crude of lemon grass, (C) crude of cassia leaves, (D) crude of clove leaves, and (E) water as control treatment were used. Ambon Hijau cultivar derived from tissue culture propagation of 2 months after acclimatization was used as experiemental material. The result showed that application of leaves of plant producing essential oils decreased initial number of Foc propagules in the banana cultivation media. Percentage of reducing the number of initial propagule of Foc in medium after infestation of plant producing essential oils ranged between 50.1-70.6%. All application of plant producing essential oils, except crude of patchouly leaves, was effective to reduce the incidence of wilting or incubation period of the disease.  The longest disease incubation period was determined on treatment with clove leaves, followed by cassia and lemon grass leaf with extending incubation period up to 22 and 15 days respectively compared to control. Application of the plant producing essential oils was not successfully applied in suppressing the percentage of wilt and disease intensity on banana under screenhouse condition. Therefore combination treatments with other techniques in conjunction to improve the effectivity of the plants in controlling Fusarium wilt disease are suggested.

scholarly journals Effect of Cultural and Biological Treatments in Managing Clubroot Disease of Cabbage in Sidhuwa, Nepal

2019 ◽  
Vol 7 (1) ◽  
pp. 96-101
Author(s):  
Ashish Ghimire ◽  
Sundarman Shrestha
Keyword(s):  
Disease Control ◽  
Disease Severity ◽  
Disease Incidence ◽  
Block Design ◽  
Combined Treatment ◽  
Severity Index ◽  
Disease Severity Index ◽  
Effective Microorganisms ◽  
Clubroot Disease ◽  
Biological Treatments

The Plasmodiophora brassicae Woronin is an important soil pathogen that attacks brassicaceae family of plants. The ability of pathogen to survive in soil for many years as a resting structure even in the absence of suitable host has increased its threat by making it more devastating. Lower effectiveness of treatments applied so far and failure to completely eradicate the disease once it enters the field has posed more problems. The study was conducted at a disease infected field in Sidhuwa, Dhankuta. It was focused on the effectiveness of different cultural and biological treatments against clubroot disease under field conditions. The treatments; lime, combination of lime and vermicompost, Effective Microorganisms (EM) solution and Trichoderma viride were arranged in Randomized Complete Block Design and replicated four times. The yield and yield attributing parameters and clubroot scale were recorded at the time of harvest. Values like Disease Incidence, Disease Severity Index and Disease Control Percentage were calculated based on clubroot scale value. The treatments showed no significant influence on vegetative parameters of the plants and on disease incidence. However, the combined treatment of lime and vermicompost was found to be most effective regarding disease severity and disease control i.e. the least Disease Severity Index (31.25%) and highest Disease Control Percentage (50.94%) compared to the control were obtained from the combined treatment of lime and vermicompost. Effective Microorganisms showed the highest disease severity. The combination of lime and vermicompost used as a treatment yielded highest marketable head weight (1.779 kg) and head diameter (19.90 cm). Int. J. Appl. Sci. Biotechnol. Vol 7(1): 96-101

scholarly journals Indonesian red chilli (Capsicum annuum L.) capsaicin and its correlation with their responses to pathogenic Fusarium oxysporum

2018 ◽  
Vol 1 (2) ◽  
pp. 7
Author(s):  
Rejeki Siti Ferniah ◽  
Sri Pujiyanto ◽  
Hermin Pancasakti Kusumaningrum
Keyword(s):  
Disease Resistance ◽  
Fusarium Oxysporum ◽  
Disease Severity ◽  
Food Industry ◽  
Regression Coefficient ◽  
Severity Index ◽  
Post Inoculation ◽  
Disease Severity Index ◽  
Commercial Crop

Red chili is a commercial crop for the food industry in Indonesia. There are some categories of red chili based on their pungency. The hot chili usually has more capsaicin than the sweet chili. Some cultivars may have more resistance to pathogen infection than the others. This research aimed to analyze the disease resistance of red chili cultivars from Indonesia against pathogenic Fusariumoxysporum and the correlation with capsaicin contents. Disease resistance was examined by determination of the Disease Severity Index (DSI) 15 dpi (days post inoculation). The correlation was analyzed by the regression coefficient. The result showed that the most resistance cultivar against F. oxysporum was Branang, while Lembang-1displayed the contrary. There was not a correlation of capsaicin content with the chili resistance to F. oxysporum.

scholarly journals Viabilitas dan Virulensi Fusarium oxysporum f. sp. cubense yang Dipreservasi dengan Liofilisasi

2018 ◽  
Vol 22 (2) ◽  
pp. 167
Author(s):  
Iqna Khayatina Rusli ◽  
Arif Wibowo ◽  
Christanti Sumardiyono
Keyword(s):  
Fusarium Oxysporum ◽  
Disease Severity ◽  
Severity Index ◽  
Wilt Disease ◽  
Pathogenicity Test ◽  
Disease Severity Index ◽  
Banana Production ◽  
The World ◽  
Very High

Wilt disease caused by Fusarium oxysporum f. sp. cubense (Foc) is still pose as  constraint  to banana production  all over the world. The objective of this research was to examine the viability and virulence of Foc isolates which had been preserved with lyophilization for 18 years. The experiment used 19 isolates of Foc, which were Pekulo, Sukorejo, Kali Sepanjang, Kalibaru, Purwojoyo, Prembun, Mulyosari, Sidogede, Sidatan, Kemiri, Juwangen, A-17, A-11, PS-5, B4-3-1, Fo2.16.16., PS-10, A-2, and Irja. The results showed that 12 isolates could grow well on PDA medium, namely Pekulo, Sukorejo, Kali Sepanjang, Kalibaru, Purwojoyo, Prembun, Mulyosari, Sidatan, Juwangen, PS-5, B4-3-1, and Fo2.16.16. Meanwhile, seven isolates (Sidogede, Kemiri, A-17, A-11, PS-10, A-2, and Irja) could not grow or develop on PDA medium. The result of pathogenicity test showed that six tested Foc isolates had  very high virulences, with disease severity index of about 2.14–2.71. Other three isolates revealed high virulences with disease severity index around 2.01–2.07. Meanwhile, another three less virulent isolates demonstrated disease severity index in the range of 1.39–1.67. Intisari Penyakit layu yang disebabkan oleh jamur Fusarium oxysporum f. sp.cubense (Foc) masih menjadi kendala dalam produksi pisang di seluruh dunia. Tujuan dari penelitian ini adalah untuk menguji viabilitas dan virulensi isolat Foc yang telah dipreservasi dengan liofilisasi selama 18 tahun. Penelitian menggunakan 19 isolat Foc yaitu Pekulo, Sukorejo, Kali Sepanjang, Kalibaru, Purwojoyo, Prembun, Mulyosari, Sidogede, Sidatan, Kemiri, Juwangen, A-17, A-11, PS-5, B4-3-1, Fo2.16.16., PS-10, A-2, dan Irja. Hasil penelitian menunjukkan bahwa 12 isolat Foc mampu tumbuh dengan baik pada medium PDA yaitu Pekulo, Sukorejo, Kali Sepanjang, Kalibaru, Purwojoyo, Prembun, Mulyosari, Sidatan, Juwangen, PS-5, B4-3-1, dan Fo2.16.16. 7 isolat tidak mampu tumbuh pada medium PDA yaitu Sidogede, Kemiri, A-17, A-11, PS-10, A-2, dan Irja. Enam isolat Foc yang diuji memiliki virulensi sangat tinggi dengan indeks keparahan penyakit berkisar antara 2,14–2,71. Tiga isolat yang lain memiliki virulensi tinggi dengan indeks keparahan penyakit berkisar antara 2,01–2,07. Sedangkan 3 isolat lainnya memiliki virulensi yang lebih rendah dengan indeks keparahan penyakit berkisar antara 1,39–1,67. 

scholarly journals Biological Management of Banana Fusarium Wilt Caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 Using Antagonistic Fungal Isolate CSR-T-3 (Trichoderma reesei)

2020 ◽  
Vol 11 ◽  
Author(s):  
Thukkaram Damodaran ◽  
Shailendra Rajan ◽  
Manoharan Muthukumar ◽  
Ram Gopal ◽  
Kavita Yadav ◽  
...  
Keyword(s):  
Gene Expression ◽  
Biological Control ◽  
Fusarium Oxysporum ◽  
Trichoderma Reesei ◽  
Disease Severity ◽  
Expression Analysis ◽  
Gene Expression Analysis ◽  
Severity Index ◽  
Disease Severity Index ◽  
Race 4

Fusarium wilt in bananas is one of the most devastating diseases that poses a serious threat to the banana industry globally. With no effective control measures available to date, biological control has been explored to restrict the spread and manage the outbreak. We studied the effective biological control potential of different Trichoderma spp. in the management of Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4). Expression of the defense related genes and metabolites in banana plants inoculated with Foc TR4 and treated with effective Trichoderma sp interactions were also studied. The in vitro growth inhibition of Foc TR4 by Trichoderma reesei isolate CSR-T-3 was 85.19% indicating a higher antagonistic potential than other Trichoderma isolates used in the study. Further, in in vivo assays, the banana plants treated with the isolate CSR-T-3 T. reesei had a significant reduction in the disease severity index (0.75) and also had increased phenological indices with respect to Foc TR4 treated plants. Enhanced activity of defense enzymes, such as β-1, 3-glucanase, peroxidase, chitinase, polyphenol oxidase, and phenylalanine ammonia lyase with higher phenol contents were found in the Trichoderma isolate CSR-T-3 treated banana plants challenge-inoculated with Foc TR4. Fusarium toxins, such as fusaristatin A, fusarin C, chlamydosporal, and beauveric acid were identified by LC-MS in Foc TR4-infected banana plants while high intensity production of antifungal compounds, such as ß-caryophyllene, catechin-o-gallate, soyasapogenol rhamnosyl glucoronide, peptaibols, fenigycin, iturin C19, anthocyanin, and gallocatechin-o-gallate were detected in T. reesei isolate CSR-T-3 treated plants previously inoculated with Foc TR4. Gene expression analysis indicated the upregulation of TrCBH1/TrCBH2, TrXYL1, TrEGL1, TrTMK1, TrTGA1, and TrVEL1 genes in CSR-T-3 treatment. LC-MS and gene expression analysis could ascertain the upregulation of genes involved in mycoparasitism and the signal transduction pathway leading to secondary metabolite production under CSR-T-3 treatment. The plants in the field study showed a reduced disease severity index (1.14) with high phenological growth and yield indices when treated with T. reesei isolate CSR-T-3 formulation. We report here an effective biocontrol-based management technological transformation from lab to the field for successful control of Fusarium wilt disease caused by Foc TR4 in bananas.

scholarly journals PENGIMBASAN KETAHANAN BIBIT PISANG AMBON KUNING TERHADAP PENYAKIT LAYU FUSARIUM DENGAN BEBERAPA JAMUR ANTAGONIS

2009 ◽  
Vol 9 (2) ◽  
pp. 130-140
Author(s):  
Loekas Soesanto ◽  
Ruth Feti Rahayuniati
Keyword(s):  
Population Density ◽  
Incubation Period ◽  
Disease Severity ◽  
Induced Resistance ◽  
Fusarium Wilt ◽  
Block Design ◽  
Antagonistic Fungi ◽  
Trichoderma Koningii ◽  
Randomized Block Design ◽  
Induce Resistance

Induced resistance of Ambon Kuning cultivar banana seedling to fusarium wilt with antagonistic fungi.  A research aiming at knowing the effect of antagonistic fungi supernatant on banana induced resistance, Fusarium wilt development, and banana growth was carried out from July up to December 2008. Randomized Block Design was used with four replicates. Treatments tested were control, with supernatant of Gliocladium virens, Trichoderma harzianum isolated from banana, ginger, and ginseng, Trichoderma koningii, and Fusarium equiseti, applied by injection to banana seedling corm and soaked for five minutes. Variables observed were incubation period, disease severity, Foc population density, germination inhibition, growth component, phenolic compound content, and supporting component. Result of the research indicated that the supernatant of G. virens, T. harzianum, and T. koningii could significantly induce resistance of the seedling showed by increasing the phenolic content such as glycoside, saponin, and tannin. The supernatant of all antagonistic fungi could effectively control the disease showed by lengthening incubation period as 48.71%, decreasing the disease severity as 53.57%, decreasing infection rate as 61.48%, increasing the antagonistic effectivity as 51.26%, decreasing the late population density as 45.35%, and decreasing the inoculum inside the plant as 60-100%. The extract could improve the seedling growth.

EVALUATION OF NONIONIC SURFACTANTS FOR CONTROL OF CLUBROOT OF CABBAGE USING BAREROOT AND PLUG TRANSPLANTS OF TWO CULTIVARS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 607b-607
Author(s):  
W. Tietjen ◽  
P.J. Nitzsche ◽  
W.P. Cowgill ◽  
M.H. Maletta ◽  
S.A. Johnston
Keyword(s):  
Brassica Oleracea ◽  
Disease Severity ◽  
Nonionic Surfactants ◽  
Plasmodiophora Brassicae ◽  
Severity Index ◽  
Effective Control ◽  
Disease Severity Index

`Market Prize' and `Bravo' cabbage (Brassica oleracea Var. capitata L.), transplanted as peat plug and bareroot plants into a field naturally infested with Plasmodiophora brassicae, Woronin, were treated immediately after planting with a liquid or a granular surfactant. APSA 80™, applied in transplant water, significantly reduced percent clubbing and disease severity index (DSI) compared to control treatments. Miller Soil Surfactant Granular™ did not significantly reduce percent clubbing or DSI. There was a significant effect of cultivar on percent clubbing and DSI. There was no significant effect of transplant type on percent clubbing or DSI. This year's study culminates five years of investigation of surfactants for clubroot control. Specific surfactants have proven to be an effective control of clubroot in cabbage. Chemical names used: nonylphenoxypolyethoxyethanol (APSA 80™); alpha-alkanoic-hydro omega-hydroxy poly (oxyethylene) (Miller Soil Surfactant Granular™).

scholarly journals Summer Heat and Low Soil Organic Matter Influence Severity of Hazelnut Cytospora Canker

2014 ◽  
Vol 104 (4) ◽  
pp. 387-395 ◽  
Author(s):  
Jay Ram Lamichhane ◽  
Alfredo Fabi ◽  
Leonardo Varvaro
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Disease Severity ◽  
Severity Index ◽  
Stress Factors ◽  
Disease Severity Index ◽  
Positive Correlation ◽  
Summer Heat ◽  
Production Areas ◽  
Cytospora Canker

Cytospora canker, caused by the fungus Cytospora corylicola, is present in hazelnut production areas worldwide. The disease is widespread throughout the main production areas of Italy. The causal agent is considered to be a secondary invader of damaged tissue that attacks mainly stressed plants. However, little is known of disease severity and stress factors that predispose plants to infection. In particular, the role of pedoclimatic factors was investigated. Direct survey indicated that disease severity varied across several study sites. Geostatistics showed a strong positive correlation between disease severity index and summer heat (r = 0.80 and 0.91 for July and August, respectively) and strong negative correlation between disease severity index and soil organic matter (r = –0.78). A moderate positive correlation between disease severity index and magnesium/potassium ratio (r = 0.58) and moderate negative correlations between disease severity index and total soil nitrogen (r = –0.53), thermal shock (r = –0.46), and rainfall (r = –0.53) were determined. No significant correlation between disease severity index and soil aluminum (r = –0.35), soil pH (r = –0.01), and plant age (r = –0.38) was found.

scholarly journals Diallel analysis of maize resistance to Phaeosphaeria maydis

2004 ◽  
Vol 61 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Herberte Pereira da Silva ◽  
José Roberto Moro
Keyword(s):  
Disease Severity ◽  
Block Design ◽  
Genetic Resistance ◽  
Diallel Analysis ◽  
Inbred Lines ◽  
Randomized Block Design ◽  
Whole Plant ◽  
Sources Of Variation ◽  
Specific Hybrid ◽  
Additive Genetic Effects

In breeding programs directed towards genetic resistance against diseases, the estimation of genetic parameters that control resistance allows the introduction of resistance into suscetible germplasm to be clearly focused. The purposes of this study were to estimate heterosis effects, and the general (GCA) and specific (SCA) combining abilities by using two rating methods for resistance to Phaeosphaeria maydis in a diallel analysis of 36 F1 maize hybrids and their nine inbred lines. Trials were conducted in three environments. Disease severity was evaluated in the whole plant (PI) and in the leaf positioned just below the point of insertion of the main ear (AFA). The trials followed a randomized block design with plots represented by a 5 m long rows. Differences among combining ability estimates for different environments and in both evaluation methods showed significant effects (P < 0.01) for environment (E), GCA, and GCA × E. The SCA, and SCA × E effects were not significant for any of the disease severity variables. The GCA effects were more important than SCA for this set of inbred lines, suggesting that additive genetic effects are the most important sources of variation for this trait. Heterosis effects for resistance were estimated, and it was possible to identify specific hybrid combinations between lines which have high potential for genetic control of this pathogen. Results for both disease severity variables were practically identical, even though the PI method was more convenient to use.

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