Evaluation of pigeon pea germplasm for yield, yield components and resistance to Fusarium wilt disease. Fusarium wilt (Fusarium udum Butler) is the most widespread and devastating disease of pigeon pea, causing yield losses as high as 50–100% in susceptible cultivars (Soko, 1992).
Literature review
Introduction
Taxonomy of Cajanus
Reddy (2004) also proposed TBM, MAS and introgression through backcross (BC) programs between pigeonpea and cross-compatible species producing more or less fertile hybrids in the primary and secondary gene pool. Reddy (2004) also suggested that protoplast fusion supported by molecular markers would be suitable for crossing pigeonpea with cross-compatible species, producing non-viable hybrids in the same tertiary gene pool and other gene pools.
Origin and distribution of pigeonpea
For crosses with a tertiary gene pool, embryo rescue, chromosome doubling and BC + MAS would be suitable for crosses between pigeonpea and cross-compatible species, producing viable but sterile hybrids.
Importance of pigeonpea
The dry stems of pigeon pea are an important domestic fuelwood (Chatarvedi et al., 2001; Shiying et al., 2001). The leaves can be used to treat jaundice, trauma, cough, burn infection and bedsores (Shiying et al., 2001).
Production constraints on pigeonpea
These are abiotic constraints such as soil pH lower than 5.0 or higher than pH 8.0, poor soil nutrient status, drought stress, favorable conditions for water logging and low light intensity ( Chauhan, 1990). Work is underway at ICRISAT in Kenya to breed pigeons for specific environments such as high latitude areas (ICRISAT, 2007).
Fusarium wilt disease
- Disease symptoms
- Disease epidemiology
- The fungus Fusarium udum (Butler)
- Disease control measures
When the bark of such strips is peeled off, browning or blackening of the underlying wood can be observed (Reddy et al., 1990). However, the use of resistant cultivars can only be successful if used as an integral part of an overall IPM program (Infantino et al., 2006).
Breeding pigeonpea
- Breeding techniques in pigeonpea
- Breeding for disease resistance in pigeonpea
- Breeding for Fusarium wilt resistance in pigeonpea
Stable yield is sought by incorporating resistance to biotic stresses such as diseases (wilt, sterility mosaic, phytophthora blight), pests and abiotic stresses (waterlogging, drought, acidity and salinity) (Singh et al., 1990). Pigeonpea has a significant amount of non-additive genetic variance and hybrid vigor for yield (Singh et al., 1990).
Mechanisms of host plant disease resistance
Breeding for wilt-resistant genotypes began in India as early as 1906 when the Fusarium wilt pathogen was identified (Reddy et al., 1990). Breeding for Fusarium wilt resistance is usually done by pedigree or mass pedigree selection, although in some cases backcrossing has also been successful (Singh et al., 1990).
Genetics of Fusarium wilt resistance in pigeonpea
Breeding for chemical resistance could therefore be more beneficial than mechanical resistance due to the inhibitory properties of the chemicals on the progression of the pathogen in the host. Clearly, there is a need for a better understanding of the inheritance of resistance, especially given that genotypes exhibit different levels of resistance under field conditions (Reddy et al., 1990).
Screening techniques of pigeonpea for Fusarium wilt disease
The distribution of the pathogen in the soil is not equal and this leads to the removal of diseases in some cultivars. Second, disease expression varies from season to season, depending on soil environmental conditions such as moisture content, soil temperature, and soil texture (Burgess et al., 1994).
Marker-assisted selection of host plant resistance
Despite the method (rotating shakers or chaff) used to propagate the inoculum, the fungus develops different types of reproductive propagules (micro- or macroconidia, chlamydospores and hyphae) (Tuite, 1969), which would make it difficult to predict, whether they will all germinate and infect the plants. The stress comes in the form of the roots being crushed, the amount of water being reduced and the plants being exposed to high temperatures (Burgess et al., 1994).
Summary
Investigation of pathogenic variations of Fusarium udum, the cause of wilt in pigeonpea (Cajanus cajan). Pigeon Improves Livelihood: Diversifying Pigeon Genetics to Increase Productivity in East and Southern Africa.
Participatory study of pigeonpea farming system, landraces, and the preferred traits
Introduction
Participatory variety selection contributes to the identification of materials that have characteristics that correspond to farmers' preferences (Danial et al., 2007). In most situations, local varieties remain the primary source of germplasm for the majority of smallholder farmers (Almekinders and Elings, 2001; Manu-Aduening et al., 2006).
Materials and methods
- Description of the study area
- Survey of pigeonpea production and marketing
- Pigeonpea germplasm collection
- Farmers’ and buyers’ participatory variety selection (PVS)
- Data analysis
The study team consisted of the principal investigator (plant breeder), the plant pathologist from MOAFS, and an extension agent from EPA. Marketing managers or owners of the pigeonpea procurement companies were interviewed about market preferences, constraints and processing of pigeonpea.
Results
- Pigeonpea cropping system
- Pigeonpea uses and marketing
- Pigeonpea production constraints
- Fusarium wilt disease in pigeonpea
- Pigeonpea cultivar preferences
- Participatory variety selection
Most farmers (83.6%) reported growing pigeon pea cultivars susceptible to Fusarium wilt (Figure 2.21). The remaining farmers indicated that the disease occurred in the area, but was not serious (Table 2.6). Buyers' expectations were mainly focused on good quality seeds (80% of buyers) and high yield varieties for farmers (20%) (Figure 2.27).
Discussion and conclusion
Local landraces, which are predominantly late maturing, make up a large part of the pigeon pea production in the country. The low acceptance of the released wilt-resistant varieties can be attributed to a lack of farmer-preferred traits in the improved varieties. Most of the tobacco estates in the southern region of the country use pigeon peas as an integral part of the ration for the workers.
The integration of farmers' knowledge, attitude and practice in the development of sustainable striga control interventions in southern Mali. The Ministry of Agriculture, Department of Agricultural Research, Maize Agricultural Report for the 1991/92 Season: Maize Commodity Team. Functioning of agricultural labor markets: Micro-evidence from an agriculturally developed region of Himachal Pradesh.
Appendix
Abstract
Introduction
Therefore, the -1 compatibility of the varieties in the interculture system is crucial for the expression of the yield components (Singh et al., 1995). Lack of improved genotypes is often cited as one of the reasons for low yields of pigeonpea (Chauhan, 1990). Patel and Patel (1998) added number of clusters plant-1, pod thickness, methionine content (%) and total soluble sugar content (%) in their characterization of pigeon pea germplasm.
Materials and methods
- Selection of genotypes used in the evaluation trials
- Evaluations of yield and plant descriptors of local landraces and ICRISAT cultivars
- Screening of pigeonpea local landraces and ICRISAT cultivars for Fusarium wilt resistance through natural inoculation
- Data analysis
Therefore, the aim of this study was to evaluate the germplasm of Malawian pigeonpea and ICRISAT cultivars for yield and yield components and resistance to Fusarium wilt. The trial at the Bvumbwe Research Station in 2004/05 was converted from a disease to a yield evaluation trial in the first year due to the low Fusarium disease pressure. a B. Fusarium wilt examination in the hospital field: a) Experimental setup, b) Infection and damage due to Fusarium wilt.
Results
- Evaluations of pigeonpea yield and yield components
The results of combined yield analysis over two seasons at Kandiya Research Station showed that AP10 and ICEAP00068 were consistently high yielders (Figure 3.8a), while KAT60/8 and AP 10 were high yielders for Bvumbwe Research Station (2004/05) and Kandiya Research Station Figure 3.8b). The number of primary and secondary branches differed significantly between genotypes (P < 0.05) (Figure 3.9, Appendix 3.3). All six medium-length genotypes from ICRISAT took less than 100 days to reach 50% flowering in the first season (Figure 3.12a).
Genotypes
Screening of pigeonpea germplasm for Fusarium wilt disease resistance through natural infection
The results showed that genotypes varied significantly (P < 0.001) in their response to Fusarium wilt under natural infection, both in Bunda College and Bvumbwe Research Station diseased plots (Figure 3.18, Appendix 3.7). Apart from AP1, all genotypes showed higher disease incidence in the second year (2005/06) than in the first year (Figure 3.18). The combined analysis for both Bunda College and Bvumbwe Research Station diseased plots over two seasons showed that genotypes varied significantly (P < 0.001) in their response to Fusarium wilt (Figure 3.20).
Discussion and conclusion
These genotypes have shown potential in Kenya and Tanzania (2Dr. Said Silim, personal communication, 2008) and should be evaluated for their potential in Malawi or used in a breeding program. Most of the local landraces in this study had large seeds (>15 g per 100 seeds. Seed size is a very important trait, both at the household and industrial levels. Most of the landraces matured at the same time, if not later, than the two variants (ICP9145 and .. ICEAP00040) issued in the country.
Appendices
Weather information for the 2004/05 and 2005/06 seasons
Yield performance of pigeonpea genotypes at Kandiya and Bvumbwe Research, Malawi
Variations in number of primary and secondary branches for
Variations in seed pod -1 and seed weight for pigeonpea genotypes Seed pod -1 Seed weight (100 seed weight g)
Days to 50% flowering for various pigeonpea genotypes at Kandiya Research Station, Lilongwe, Malawi
Variations in plant height (m) and stem diameter (mm) for pigeonpea genotypes
Reaction of genotypes to Fusarium wilt disease at Bunda College and Bvumbwe sick plots
Development of a new screening
Introduction
- Screening pigeonpea for Fusarium wilt resistance
- Isolation of Fusarium udum from plants
- Preservation of Fusarium spp isolates
- Multiplication of inoculum
Furthermore, the expression of the disease varies across the season, depending on the environmental conditions in the soil, such as moisture content, soil temperature and soil structure (Burgess et al., 1994). The effectiveness of this technique depends on the age of the plant and the spore concentration. With prolonged cultivation of the fungus, pathogenicity may be lost, or at least virulence may be diminished (Kiraly et al., 1970; Burgess et al., 1994).
Materials and methods
- Isolation, purification, and identification of the pathogen
- Preservation of the isolates
- Multiplication of inoculum
- Pathogenicity test for Fusarium udum pathogen
- Selection of the genotypes for the screening technique
- Development of the infested seed inoculation technique
- Disease assessment
- Data analysis
Two hundred grams of this inoculum is well mixed with 2 kg of autoclaved soil in pots; pigeon seedlings were planted in the pots. Eight genotypes were used in the actual inoculation technique and these were carefully selected based on their resistance or susceptibility to Fusarium wilt disease and duration to maturity (Table 4.1). Analysis of variance (ANOVA) from the Genstat statistical package was used and the analyzed data were presented in the form of tables and graphs.
Results
- Isolation, purification and identification of the pathogen
- Preservation of the isolates
- Multiplication of inoculum
- Pathogenicity test for Fusarium udum pathogens
- Inoculation technique for Fusarium udum pathogen
Isolates grown in three different media: finger millet, sorghum and wheat were equally virulent. There were significant differences (P<0.001) in the reactions of genotypes to artificial inoculations in the greenhouse (Figure 4.8 and Appendix 4.1). There were no significant differences (P>0.05) in genotype response when inoculum levels were increased from one to ten seed plants-1 (Figure 4.9 and Appendix 4.2).
Discussion and conclusion
In the methods where only spores are used in the inoculation process, the dormancy of the spores before germination affects the results. Due to the presence of both mycelia and spores, there is an assurance of infection. The applicability of the technique to other pathogens and crops is of interest to plant breeders.
Inheritance of resistance to Fusarium wilt and yield traits in pigeonpea
- Introduction
- Materials and methods
- Pigeonpea genotypes used in the breeding programme
- Line x tester mating scheme
- Evaluation of pigeonpea F 1 crosses for Fusarium wilt resistance Screenhouse trial: In the screenhouse, F 1 plants were evaluated for resistance to
- Screening pigeonpea F 2 lines for Fusarium wilt resistance
- Genetic analysis of Fusarium wilt, yield and secondary traits
- Results
- Gene action controlling wilt resistance, yield and secondary traits The Restricted Maximum Likelihood (REML) analysis of the F 1 crosses data (Table 5.2)
Therefore, it was important to determine the heritability (h2n) of Fusarium wilt resistance in local landraces. Two of the testers had already been marketed in Malawi as late-maturing, Fusarium wilt-resistant varieties (ICP9145 and ICEAP00040). Approximately 63% of the F1 crosses were resistant to Fusarium wilt at the end of the trial (Table 5.3).
97.3 P value <0.001
- Relative importance of the GCA and SCA effects
- General combining ability in pigeonpea landraces and testers
- Specific combining ability effects for pigeonpea crosses
- Segregation analysis of F 2 population for resistance to Fusarium wilt The F 2 lines segregated in their reaction to wilt. Table 5.10 shows the number of plants
- Discussion and conclusion
Positive GCA effects were desired for the number of seeds pod-1, while negative GCA effects were not desired. Positive GCA effects were desired for the number of primary branches, while negative GCA effects were not desired. The GCA and SCA effects were significant for wilt resistance, days to 50% flowering, number of secondary branches in both parents, and in the interaction of the parents.
Research overview: Implications of research findings for pigeonpea breeding
These lines were used as parents in a breeding program to develop fusarium wilt resistant lines with traits preferred by farmers and consumers. g) During genotype evaluation, some local landraces were found to have inherent wilt resistance, high yield and early maturity. Most of the F1 crosses were resistant to fusarium wilt, which was due to additive and non-additive genetic effects. l) Chi-square analyzes yielded segregation ratios of 9:7 (resistant:susceptible), except for a few crosses that could not be included in any known segregation ratio in the F2 generation. Therefore, the continued involvement of farmers in the entire crop improvement program is very important.
