The inheritance of grain yield and rust resistance of pearl millet is controlled by additive gene effects. Chapter Four: Combining ability and heterosis for grain yield and rust resistance in pearl millet.
Introduction
Taxonomy and genetics of pearl millet
Gene pool and sources of diversity
The tertiary gene pool has both sexual and apomictic species that are both diploid and polyploid and the majority belong to the x=9 group. But Hanna (1987) suggested that the tertiary gene pool could be a good source of resistance genes for striga resistance (Wilson et al., 2001) and used for apomictic production, perennial growth habit, drought tolerance, cold resistance, pest resistance and cytoplasmic diversity.
Pearl millet diseases
- History of pearl millet rust nomenclature and research
- Symptoms of pearl millet rust
- Screening techniques for pearl millet rust
- Infection and colony development of Puccinia substriata var indica
- Gene action for pearl millet rust resistance
Among the races, indica and penicillaria are closely related and the difference between them is doubtful (de Carvalho et al., 2006). The disease starts from urediniospore (Thakur et al., 2011). Taylor and Mims (1991) reported that for Puccinia substriata var indica.
Recurrent selection
Gene action for grain yield and yield components
Kapoor et al (1979) reported that additive gene action was predominant in the inheritance of productive offshoots, while Tomar et al. 2008) reported low heritability and low genetic gain. Dominance and additive x additive gene effects have been reported to control the inheritance of panicle length (Ghandhi et al. also observed a variation in gene action depending on the parents used in the crosses.
Heterosis
Rasal and Patil (2003) reported that the trait is highly influenced by additive gene effects, while Rathore et al. 2004) reported that both additive and non-additive gene action operated simultaneously. On the contrary, Azhaguvel and Jayaraman (1998) and Lakshmana and Guggari (2001) earlier reported that non-additive gene action was dominant when they observed high heritability but low genetic gain for days up to 50%.
Correlation analysis
Genotype x environment analysis
When Yahaya et al. 2006) used linear regression to characterize hybrids in Nigeria based on yield, the non-linear component accounting for the greatest variation. The SHMM method is more sensitive than AMMI because it incorporates all variance components in the analysis (G, E, and GE) which makes it more precise, but has not been investigated as much in pearl millet.
Participatory Rural appraisal in pearl millet breeding
Despite the high variability in farmers' preferences established through participatory rural appraisal, such studies have not been conducted in Uganda. Therefore, it is necessary to conduct participatory rural evaluation studies in Uganda in order to develop pearl millet varieties with the desired characters of farmers.
Research gaps identified from the review of the literature
Evaluation of heterosis and combining ability of leaf area (LA), leaf area ratio (LAR) and grain yield in pearl millet.
Introduction
This is important because there is little information on pearl millet research in Uganda; production characteristics are combined with those of finger millet. The information from the basic research will thus be used to develop an effective participatory plant breeding program that takes into account the opinions of pearl millet users.
Materials and methods
- Study area
- Selection of farmers and enumerators
- Data collection
- Data analysis
Pearl millet production is mainly located in three regions (North, East and North East) of Uganda. However, in northern Uganda, some respondents who had grown the crop in the past year were considered as long as they had some experience in pearl millet cultivation.
Results
Importance and utilisation of pearl millet
- Importance of pearl millet in terms of cultivation frequency and being food
- Ranking of pearl millet relative to other crops
- Uses and utilisation of pearl millet
The ranking was defined as the average of the ranking of pearl millet as a food crop and the ranking as a source of income. Substitution of grains for other foods has been one of the strategies to manage the use of pearl millet as a food security crop.
Use of improved inputs and improved technologies
Access to improved seed and sources of seed
Access to fertilisers, manure, pesticides and herbicides
Access to social services
Agronomic factors
Farming activities
Cropping systems, planting methods and season of planting
Farmers’ desirable and undesirable pearl millet traits
Traits of the farmers’ pearl millet genotypes
Desirable traits and attributes to be improved or introduced
They noted that pearl millet varieties should have traits such as ergot resistance, high yielding varieties with large white grains and early maturity. However, other important factors to consider should include introduction of appropriate pesticides and provision of a sustainable market for cereals, training in the use of fertilizers/manures and development of non-itching varieties (Figure 2.18). .
Undesirable traits in the farmers’ pearl millet genotypes
Pearl millet production and marketing constraints
Field constraints and control adopted strategies
Most farmers had no control over the birds, although some claimed that planting in the second rains minimized their effect. Weeding was noted as the best control strategy against weeds, while farmers had no control measures against rust and insect pests.
Storage and taste constraints and adopted control strategies
Marketing constraints, control strategies and access to markets
Important production determinants of pearl millet
Other important factors with a positive effect were the age of spouse (which accounted for 87% female), followed by years of pearl millet cultivation. Results in Table 2.9 further show that distance to the markets where the grain was sold or grain seed was bought and age of the heads of households were significantly important, but had a negative effect on pearl millet production.
Discussion
- Importance and utilisation of pearl millet
- Use of improved inputs and technologies and access to social services
- Agronomic factors
- Farmers’ desirable traits and undesirable traits
- Production and marketing constraints
- Modelling for important determinants of production
However, higher grain yield is obtained if weeding is performed more than once (Tenebe et al., 2012). Soot and blast were other field constraints not mentioned by farmers but observed in the pearl millet fields (Lubadde et al., 2014).
Conclusion
Components for the management of two insect pests of pearl millet in Sahelian West Africa. Genetic improvement of pearl millet and sorghum for the semi-arid tropics of Asia and Africa.
Introduction
This can be achieved through recurrent selection, because it leads to the accumulation of many gene loci with small effects (Menkir and Kling, 2007). Additionally, successful improvement of swine downy mildew resistance was achieved through repeated selection of complete sib and S1 progeny by Weltzien and King (1995).
Materials and Methods
- Experimental materials
- Developing the S 1 progeny recurrent selection cycles
- Field evaluation of the experimental materials (C 0 , C 1 and C 2 )
- Data collection and analysis
The farmers described the population from the east (Omoda) as precocious and small (125 cm), while that from the north (Lam) was late maturing and tall and these were used to form C0 for each population and therefore C1 and C2. develop cycles. by phenotypic S1 progeny recurrent selection. A summary of the recurring selection schedule indicating the time frame is shown in Table 3.1.
Results
- Analysis of variance of the three cycles
- Broad sense heritability estimates
- Mean performance of the three cycles
- Genetic gains from two cycles of S 1 progeny recurrent selection
- Correlations for selected traits with grain yield
However, grain yield had a significant negative correlation with rust severity at 50% physiological maturity, days to 50%. Days to 50% anthesis had a positive correlation with days to 50% physiological maturity, plant height, total number of productive tillers, number of productive tillers, leaf area and biological yield.
Discussion
- Analysis of variance of the three cycles
- Broad sense heritability
- Mean performance of the cycles
- Genetic gains per cycle
- Correlations for selected traits with grain yield
The positive significant effects of these traits and a significant reduction in rust severity led to the increase in grain yield realized in C2 in the Lam population due to the phenotypic S1 progeny recurrent selection. This is an indication that increasing rust resistance will significantly increase grain yield in the Lamb population.
Conclusion
SSR allele frequency changes in response to recurrent selection for pearl millet grain yield and other agronomic traits. Association analysis of SSR markers with phenology, grain and stover yield-related traits in pearl millet (Pennisetum glaucum (L.) R. Br.).
Introduction
The diallelic cross design has been widely used in pearl millet breeding to assess the nature of reciprocity for yield-related traits. In pearl millet breeding, the design has been used to assess reactivity for downy mildew (Angarawai et al., 2008).
Materials and Methods
- Experimental materials
- Experimental sites and field layout
- Data collection
- Calculation of AUDPC and data analysis
The GCA effects of the male and female parents were estimated as the difference between the grand mean and the mean of the parents for the trait. GCAmale and GCAfemale are the general combining ability of the male and female parents respectively.
Results
- Pooled analysis of variance
- General combining ability effects for the male parents
- General combining ability effects for the female parents
- Specific combining ability effects for fifteen top ranked crosses
- Gene action and heritability
- Better-parent heterosis
The two parents also had negative GCA effects in days to 50% anthesis, flower-anthesis interval, days to 50% physiological maturity and plant height. The parent ICMV3771 also had positive GCA effects for rust severity at 50% physiological maturity, days to 50%.
Discussion
General performance of the parents and crosses
The significant difference in the flowering-anthesis interval for the parents and crosses highlights the importance of this trait. All crosses had a lower flower anthesis interval compared to all female and male parents and since they yielded better than the parents, this implies that selection on flower anthesis interval would lead to higher grain yield.
Combining ability effects and gene action
Choosing a low flower-anthesis interval will significantly increase grain yield. days to 50% flowering, days to 50% anthesis, flower-anthesis interval, days to 50% physiological maturity, plant height and number of productive tillers, however unlike Bhadalia et al. 2012) reported predominance of non-additive reaction in days to 50% flowering and days to 50% physiological maturity. Likewise, inbred lines with improved levels of the traits can be developed as suggested by Vengadessan (2008).
Heterosis
Lower levels of heterosis of the superior parent were recorded for plant height, days to 50% flowering, days to 50% flowering, flower-to-flowering interval, days to 50% physiological maturity, grain yield and 1000-grain weight, although non-additivity prevailed in the latter two properties. Karad and Harer (2004) reported high levels of heterosis in days up to 50% flowering, whereas the findings in this study indicate very low levels.
Conclusion
Gene effects and heterosis for grain iron and zinc density in pearl millet (Pennisetum glaucum (L.) R. Br). Genetic analysis of sodium content and Na/K ratio in relation to salinity tolerance in pearl millet Pennisetum glaucum (L.) R.
Introduction
The regression approach is one of the most widely used methods for estimating the GEI effect on environments (Westcott, 1986). The main drawback of the AMMI method is the difficulty in interpreting the interaction when there is a poor explanation of the first principal component, which may indicate false statistical stability of genotypes and/or environments (Lavoranti et al., 2007).
Materials and methods
Experimental layout and germplasm
However, the response of genotype to environments is itself multivariate, but regression transforms it into a univariate variable (Lin et al., 1986). The aim of the study was to analyze the patterns of GEI effects for grain yield, rust resistance and area under disease progress curve (AUDPC) for rust and to identify the winning genotypes in each of the four environments using GGE biplots.
Data collection and analysis
PC1, 𝜆2 = singular value PC2, 𝜉 𝑗 for PC2, and 𝜀𝑖𝑗 is the residual associated with genotype 𝑖 in environment 𝑗.
Results
- Performance of environments and top ranked five genotypes
- GGE biplots for grain yield
- Rust severity at 50% physiological maturity
- Area under disease progress curve
The GGE biplots show the ideal genotypes for grain yield as those close to the horizontal arrowhead line, while high-yielding genotypes are those on the right side of the graph (x-axis 0.1-0.5). Both environments were positively correlated and associated with high grain yield and clustered as one megaenvironment (Figure 5.1B).
Discussion
Conclusion
Genotype-environment interaction patterns of pearl millet for yield performance and grain iron (Fe) and zinc (Zn) concentrations in Sudan. The need for scale transformation in the analysis of genotype clusters based on multisite yield data.
Introduction
Summary of the major findings
- Participatory rural appraisal
- Recurrent selection
- Combining ability and heterosis
- Genotype by environment interaction analysis
A net genetic gain of 72% and 36% for grain yield in the Lam and Omoda populations, respectively, after the two cycles of S1 recurrent selection. A significant negative correlation between grain yield and rust resistance was noted for the two populations.
Implications of the findings for pearl millet breeding
Part 2b 3: Expenditure on other inputs used in pearl millet production and other crops in the first season. Part 4k: Average yield of pearl millet (if harvested piecewise, record and ask the farmer to estimate the total amount harvested over harvest period).
