scholarly journals Inheritance of resistance against Peronospora destructor in onion cv. ‘Regia’

2020 ◽  
pp. 1999-2009
Author(s):  
Mariana Arias ◽  
Natalia Curbelo ◽  
Pablo González Rabelino ◽  
Esteban Vicente ◽  
Gustavo Giménez ◽  
...  
Keyword(s):  
Disease Severity ◽  
Partial Resistance ◽  
Agronomic Traits ◽  
Selection Process ◽  
Genetic Resistance ◽  
Transgressive Segregation ◽  
Inheritance Of Resistance ◽  
Peronospora Destructor ◽  
Loss Of Susceptibility ◽  
Onion Downy Mildew

Onion downy mildew (DM) caused by Peronospora destructor is a very destructive leaf disease. Genetic resistance is an economic and environmentally friendly way of disease control. In this research, the segregation of DM resistance was analysed in six offspring from crosses between national cultivars and the cv. ‘Regia’, a partial resistance source. F1 plants were self-fertilised, and F1S1 derived progenies were evaluated. The segregations in DM severity were skewed towards susceptibility, with transgressive segregation in five of six progenies. The recessive inheritance could be associated with loss of susceptibility mechanisms. In another experiment, the response of advanced F1S2 lines ‘Regia’ x ‘Pantanoso del Sauce’ were evaluated two times (August and November 2017) in DM disease severity, DM histological quantitative differences, and agronomic traits. F1S2 lines, which have had an earlier selection process, presented an intermediate DM severity between the parents. Disease severity was positively correlated with histological differences in the proportion of infected stomata. ‘Regia’ presented the lowest DM severity and the highest percentage of healthy stomata. Most resistant F1S2 lines did not differ from control cultivars in bulb yield, bulb quality traits and postharvest behaviour, and could be the basis to develop a DM resistant cultivar in comparison to currently grown cultivars

Control of onion downy mildew in the presence of phenylamide-resistant strains of Peronospora destructor (Berk.) Caspary

1992 ◽  
Vol 32 (5) ◽  
pp. 669 ◽  
Author(s):  
RG O'Brien
Keyword(s):  
Downy Mildew ◽  
Disease Severity ◽  
Field Trials ◽  
Copper Hydroxide ◽  
Peronospora Destructor ◽  
Phenylamide Fungicides ◽  
Resistant Strains ◽  
Onion Downy Mildew ◽  
Reduce Disease Severity

Two isolates of Peronospora destructor differed in their sensitivities to phenylamide fungicides. An isolate (3014) from the Lockyer Valley did not respond to increasing concentrations of metalaxyl, benalaxyl and oxadixyl between 0.1 and 200 mg a.i./L. An isolate (2967) from Bundaberg was sensitive to these fungicides, with EC50 values (concentrations which reduce disease severity by 50%) of 1.6, 6.0 and 12.1 mg a.i./L, respectively. Isolates 3014 and 2967 were both sensitive to dimethomorph, with EC50 values of 4.3 and 1.4 mg a.i./L, respectively. Field trials compared the efficacy of fungicides for the control of onion downy mildew in the Lockyer Valley in 1989 and 1990. In both trials, treatments containing mancozeb gave the best control, resulting in yield increases of 60% in 1990. There was no difference from the check treatment in either disease severity or yield when metalaxyl was applied, suggesting that phenylamide-resistant strains were prevalent. Other fungicide treatments which did not significantly reduce the severity of downy mildew in the 1990 trial included copper hydroxide, chlorothalonil, fosetyl-Al, and propamocarb. The experimental compound dimethomorph, although less effective than mancozeb, significantly reduced disease severity and increased yield by 24%.

scholarly journals Selected Soybean Plant Introductions with Partial Resistance to Sclerotinia sclerotiorum

Plant Disease ◽  
2002 ◽  
Vol 86 (9) ◽  
pp. 971-980 ◽  
Author(s):  
D. D. Hoffman ◽  
B. W. Diers ◽  
G. L. Hartman ◽  
C. D. Nickell ◽  
R. L. Nelson ◽  
...  
Keyword(s):  
United States ◽  
Disease Severity ◽  
Partial Resistance ◽  
Germ Plasm ◽  
Agronomic Traits ◽  
Field Tests ◽  
The United States ◽  
Stem Rot ◽  
Sclerotinia Stem Rot ◽  
Plant Introductions

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is a major soybean (Glycine max) disease in north-central regions of the United States and throughout the world. Current sources of resistance to Sclerotinia stem rot express partial resistance, and are limited in number within soybean germ plasm. A total of 6,520 maturity group (MG) 0 to IV plant introductions (PIs) were evaluated for Sclerotinia stem rot resistance in the United States and Canada in small plots or in the greenhouse from 1995 to 1997. Selected PIs with the most resistance were evaluated for resistance in the United States and Canada in replicated large plots from 1998 to 2000. The PIs in the MG I to III tests in Urbana, IL were evaluated for agronomic traits from 1998 to 2000. The selected PIs also were evaluated with an excised leaf inoculation and petiole inoculation technique. After the 1995 to 1997 evaluations, all but 68 PIs were eliminated because of their susceptibility to Sclerotinia stem rot. In field tests in Urbana, higher disease severity in selected MG I to III PIs was significantly (P< 0.05) associated with taller plant heights and greater canopy closure. All other agronomic traits evaluated were not associated or were inconsistently associated with disease severity. MG I to III PIs 153.282, 189.931, 196.157, 398.637, 417.201, 423.818, and 561.331 had high levels of resistance and had canopies similar to the resistant checks. The resistance ratings from the petiole inoculation technique had a high and significant (P< 0.01) correlation with disease severity in the MG I and II field tests. The partially resistant PIs identified in this study can be valuable in incorporating Sclerotinia stem rot resistance into elite germ plasm.

scholarly journals New sources of partial resistance to bacterial spot race T2 in processing tomatoes

2016 ◽  
Vol 34 (3) ◽  
pp. 326-332
Author(s):  
María C Berrueta ◽  
Gustavo Giménez ◽  
Guillermo A Galván ◽  
Alejandra Borges
Keyword(s):  
Incubation Period ◽  
Disease Severity ◽  
Leaf Spot ◽  
Partial Resistance ◽  
Genetic Resistance ◽  
Bacterial Spot ◽  
Bacterial Leaf Spot ◽  
Rapid Spread ◽  
Xanthomonas Species ◽  
Processing Tomatoes

ABSTRACT Bacterial leaf spot of tomato is caused by four Xanthomonas species, among which Xanthomonas vesicatoria race T2 predominates in Uruguay. Difficulties in integrated disease management and the rapid spread of the pathogen led to investigations of genetic resistance. This study aimed to identify resistance sources to bacterial leaf spot race T2 in tomato for processing. Twelve genotypes were evaluated under field conditions in 2010 and 2011. Plants were spray-inoculated with a suspension of bacteria (108 cfu/mL) 15 days after transplantation. Incubation period, disease severity on leaves, and the percentage of fruits with symptoms at harvest were determined. The incubation period did not differ among the genotypes. The genotype 'Hawaii 7981' had the lowest leaf severity on the leaves, followed by 'Loica'. The lines (derived from the cultivar 'Loica') LB97, LB99, LB60, and LB76, and the cultivar 'Ohio 8245' showed intermediate levels of severity on leaves, whereas 'H9997', 'Cuyano', LB85, and 'NUN6011' presented higher severities. The differences in disease severity of the leaves were similar over the years, while incidence of symptoms in fruit was more variable. Next to 'Hawaii 7981', the cultivars 'Loica' and 'Ohio 8245' were identified as new sources of partial resistance to bacterial spot race T2.

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.

scholarly journals Integrating Conventional and Participatory Breeding Approaches in Assessment of Common Bean Varieties for Farmer Preffered Traits

2019 ◽  
Vol 11 (5) ◽  
pp. 104
Author(s):  
Papias H. Binagwa ◽  
Magdalena William ◽  
Julius P. Mbiu ◽  
Eunice Zakayo ◽  
Shida M. Nestory ◽  
...  
Keyword(s):  
Common Bean ◽  
Agronomic Traits ◽  
Selection Process ◽  
Block Design ◽  
Group Discussion ◽  
High Yield ◽  
Market Demand ◽  
Variety Selection ◽  
Early Maturing ◽  
Participatory Variety Selection

It is estimated that over 75% of rural households in Tanzania depend on common bean (Phaseolus vulgaris L.) for daily subsistence. Recently, farmers have been increasingly looking for improved bean varieties which meet specific market demands characterized with yellow seed colour, early maturing and/or adapted to local agro-ecologies. Study focused on assessing the performance of bean varieties for agronomic traits through variety and environmental interactions by identifying high yielding, ealy maturing and market demand seed classes among the tested materials. For testing adaptability and stability, experiments were conducted in low to high altitudes for two consecutive years using randomized complete block design (RCBD) with three replicates. Eight common bean varieties KG98, Navy line 1, KATB9, SABRYT, KATB1, Lyamungu 85, JESCA and Calima Uyole were used. Absolute, matrix and pairwise ranking were used integratively for farmers&rsquo; and researcher&rsquo;s assessment and selection. Participatory variety selection approach gave farmers an opportunity to assess and select varieties from a range of near finished materials in the breeding process. As part of the Farmers&rsquo; participatory variety selection process, seventeen participants as among the consumers 46% being women were selected to participate in a focused group discussion. Results revealed that, days to flowering, days to maturity and yield across the tested environments showed significant differences (p &le; 0.05) as well as yield and diseases interactions for genotype, environment and season. Field data and farmers&rsquo; assessment data showed two varieties of KATB1 (yellow round) and KATB9 (red round) for better performance (high yield) and grain preference respectively. It showed that, early maturing; seed type and marketability varieties are highly demanded by bean farmers in Tanzania.

Inheritance of resistance to cassava green mite and other useful agronomic traits in cassava grown in Zambia

Euphytica ◽  
2015 ◽  
Vol 205 (1) ◽  
pp. 103-119 ◽  
Author(s):  
Able Chalwe ◽  
Rob Melis ◽  
Paul Shanahan ◽  
Martin Chiona
Keyword(s):  
Agronomic Traits ◽  
Inheritance Of Resistance ◽  
Cassava Green Mite ◽  
Green Mite

scholarly journals Variability, heritability, and correlations of agronomic traits in an onion landrace and derived S1 lines

2014 ◽  
Vol 14 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Bettina Porta ◽  
Mercedes Rivas ◽  
Lucía Gutiérrez ◽  
Guillermo A Galván
Keyword(s):  
Dry Matter ◽  
Agronomic Traits ◽  
Block Design ◽  
Transgressive Segregation ◽  
Matter Content ◽  
Leaf Length ◽  
Soluble Solids ◽  
Dry Matter Content ◽  
Original Population ◽  
Random Block Design

This study assessed variability, heritability and correlations of agronomic traits in an onion (Allium cepa L.) landrace and derived S1lines after a single selfing generation. Bulbs used to develop S1lines were selected for shape, colour and high number of skins. Fifty-one S1lines and the original population were evaluated using an incomplete random block design. The original population and S1lines were highly diverse for quantitative and qualitative traits. S1lines were significantly different, with transgressive segregation for number and maximum leaf length, bulbing index, bulb weight, diameter, and dry matter content. Variances within S1lines were greater than among S1lines for all traits. Bulb colour and number of skins responded to selection. Heritabilities for dry matter and soluble solids were 52.6% and 36.1% respectively. Both traits were highly correlated. The development of S1lines allowed the expression of genetic variation and the identification of better genotypes for agronomic traits of interest.

Inheritance of resistance to Mal de Río Cuarto (MRC) disease in Zea mays (L.)

2002 ◽  
Vol 139 (1) ◽  
pp. 47-53 ◽  
Author(s):  
M. A. DI RENZO ◽  
N. C. BONAMICO ◽  
D. D. DÍAZ ◽  
J. C. SALERNO ◽  
M. M. IBAÑEZ ◽  
...  
Keyword(s):  
Zea Mays ◽  
Plant Height ◽  
Disease Severity ◽  
Agronomic Traits ◽  
Severity Index ◽  
Point Estimate ◽  
Environment Interaction ◽  
Disease Severity Index ◽  
Evaluation Activity ◽  
Genotype Environment Interaction

No genetic estimates for resistance to Mal de Río Cuarto (MRC) disease in Zea mays (L.) are currently available in the literature. Therefore, the objectives of this investigation were (i) to estimate the variance and heritability of partial resistance to MRC disease and of other agronomic traits from maize families and (ii) to examine associations among MRC disease severity values across different environments and between MRC and other agronomic traits. These estimations, obtained in an endemic area, could contribute to the design of efficient enhancement programmes and evaluation activity for the improvement of MRC resistance. The research was conducted by testing 227 F3 derived-lines from a cross between a susceptible dent line, Mo17, and a partially resistant flint line, BLS14, for MRC disease at two Río Cuarto locations in each of 2 years. The resistance of the lines, measured with a disease severity index (DSI), was normally distributed across environments. Genotypic variances were highly significant on all scoring environments. Estimates of genotype–environment interaction were also significant, suggesting that certain genotypes have little stability over different environments. For disease severity index all estimates demonstrated moderate heritabilities ranging from 0.44 to 0.56 and were similar when based on individual environments or across environment. Confidence interval widths ranged from 34.88 to 50.30% as large as the heritability point estimate. The correlations between environments were small enough to indicate that families did not rank similarly in individual environments for MRC resistance. Disease severity index correlated significantly (P<0.01) with plant height, leaf surface, leaf border, leaf length and tassel type. Heritability estimates for plant height and tassel type were 0.48 and 0.38 respectively and for the various leaf traits heritability values were very low. On the basis of the substantial genotype–environment interaction and the little association between DSI values in the different environments, selection for an increased resistance to MRC disease would require evaluation of germplasm across multiple years and locations. Tassel type would be a useful predictor of DSI and can be used effectively to improve screening procedures.

Breeding healthy cereals: genetic improvement of Fusarium resistance and consequences for mycotoxins

2015 ◽  
Vol 8 (5) ◽  
pp. 591-602 ◽  
Author(s):  
H. Buerstmayr ◽  
M. Lemmens
Keyword(s):  
Disease Severity ◽  
Genetic Resistance ◽  
Selection Response ◽  
Head Blight ◽  
Production Chain ◽  
Resistant Cultivars ◽  
Cereal Production ◽  
Food And Feed ◽  
Feed Safety ◽  
Mycotoxin Reduction

Although it is generally agreed that increased genetic resistance to fungal colonisation by Fusarium head blight (FHB) should lead to reduced damage and particularly to reduced contamination due to mycotoxins, this review aims to highlight on this relation based on published literature in comparison to our own results. We focus here on the major cereal crop plants wheat and barley. Generally, correlations between measures for disease severity on the plants or the seeds and toxin content were found positive and significant. Breeding of new cultivars with reduced Fusarium disease severity will therefore lead to a correlated selection response in the direction of reduced toxin contamination, for the prevalent toxins such as deoxynivalenol, but also for less abundant mycotoxins and masked mycotoxins. Choosing resistant cultivars is possibly the best option for mycotoxin reduction right at the beginning of the cereal production chain: on the farmer’s field. Therefore, investment in breeding FHB resistant cultivars will contribute to sustainable reduction of the mycotoxin problems in the cereal production chain, and increase food and feed safety.

Sign in / Sign up

Export Citation Format

Share Document