Genetics of grain-mould resistance and yield components in sorghum (Sorghum bicolor) varieties

Sorghum ( Sorghum bicolor (L.) Moench) is a staple food crop in the semi-arid tropical areas of Africa and India. It is also an important feed and forage crop in other parts of the world. In India, the development of short-duration and shortstatured sorghum hybrids resulted in a quantum jcrmp in productivity from 560 kg ha" in 1970 to 1020 kg ha" in 1996. However, yield potentials of sorghum hybrids are not fully realized as they are highly susceptible to grain moulds, which not only cause yield loss but also reduce grain quality and market value. For any effective kharif hybrid breeding programme, grain mould resistant male-sterile and restorer lines are essential prerequisites. Efficient exploitation of resistant genotypes in breeding grain mould resistant parental lines requires knowledge of the number and diversity of genes involved and of their mode of action in determining resistance..

Genetics of Starch Content and its Correlations with Agro-morphological Traits in Sorghum

Sorghum can be an alternative to corn for industrial uses, especially in drought prone areas of the world. Sorghum cultivars with high potential of grain and starch yields are needed to continuously meet the industrial demands. We have studied the genetics of grain yield and starch content of sorghum to decide the breeding procedure to develop suitable cultivars for starch industry. The genetic material from 8 × 8 diallel (28 F1 and 8 parents) was grown in a randomized complete block design, with three replications at Directorate of Sorghum Research, Hyderabad, India. Observations were recorded on seven agro-morphological and two grain quality traits including grain yield and starch content. Correlation studies revealed that the grain hardness was negatively correlated to starch and positively correlated to grain yield, panicle weight and days to flowering. Variance due to specific combining ability effects was greater in magnitude for both starch content and grain yield. Bi-parental crossing in F2 will help in getting pure lines with high starch content and high grain yield. The parents chosen for breeding program need to be good combiners for starch and grain yields to obtain superior hybrid. One MS line, 422B was a good combiner for grain yield, high starch content and 100 grain weight, and had good per se performance

Genetic analysis of grain mould resistance in coloured sorghum genotypes

Grain moulds are a major constraint to sorghum production and to adoption of improved cultivars in many tropical areas. Information on the inheritance of grain mould reaction is required to facilitate breeding of resistant cultivars. The genetic control of grain mould reaction was studied in 7 crosses of 2 resistant sorghum genotypes. P1, P2, F1, F2, BC1 and BC2 families of each cross were evaluated under sprinkler irrigation for field grade and threshed grade scores and subjected to generation mean analysis. Frequency distributions for grain mould reaction were derived and F2 and BC1 segregation ratios were calculated. Grain mould reaction in crosses of coloured grain sorghum was generally controlled by two or three major genes. Resistance to grain moulds was dominant. Significant additive gene effects were also found in all cross/season combinations. Significant dominance effects of similar magnitude to additive effects were also observed in five out of ten cross/season combinations. Gene interactions varied according to the parents with both resistant and susceptible parents contributing major genes. Choice of parents with complementary resistance genes and mechanisms of resistance will be critical to the success of resistance breeding

Genetic analysis of grain mold resistance in white seed sorghum genotypes

Grain molds in rainy season sorghums can cause poor grain quality resulting in economic losses. Grain molds are a major constraint to the sorghum production and for adoption of the improved cultivars. A complex of fungi causes grain mold. Information on genetics of grain mold resistance and mechanisms is required to facilitate the breeding of durable resistant cultivars. A genetic study was conducted using one white susceptible, three white resistant/tolerant sources, and one colored resistant source in the crossing programme to obtain four crosses. P1, P2, F1, BC1, and BC2, and F2 families of each cross were evaluated for the field grade and threshed grade scores, under sprinkler irrigation. Generation mean analyses and frequency distribution studies were carried out. The frequency distribution studies showed that grain mold resistance in the white-grained resistance sources was polygenic. The additive gene action and additive × additive gene interaction were significant in all the crosses. Simple recurrent selection or backcrossing should accumulate the genes for resistance. Epistasis gene interactions were observed in colored resistance × white resistance cross. Gene interaction was influenced by pronounced G × E. Pooled analysis showed that environment × additive gene interaction and environment × dominant gene interaction were significant. The complex genetics of mold resistance is due to the presence of different mechanisms of inheritance from various sources. Evaluation of segregating population for resistance and selection for stable derivatives in advanced generations in different environments will be effectiv

Grain mould resistance and associated characters of sorghum genotypes

Twenty-two sorghum genotypes were evaluated for grain mould response, 13 morphological and biochemical traits thought to contribute to resistance, and 3 agronomic traits related to utilization. Measurements of grain mould (field grade score, threshed grade score, ergosterol content, and percentage germination) were strongly correlated with one another. Highly significant correlations between measures of grain mould and seed hardness, seed phenol content in acid methanol extract, and glume colour indicated that they strongly affected grain mould response. Harder grain, higher levels of seed phenols, and darker glumes contributed to grain mould resistance. Weaker and less consistent correlations between measures of grain mould and seed colour, seed flavan-4-ol content, glume phenol and flavan-4-ol contents, and glume cover indicated relatively less effect of these traits on grain mould response. Genotype means indicated that combinations of several traits are required to achieve resistance. Germplasm lines, including coloured-seeded lines IS 14375, IS 14387, IS 18144, and IS 18528, and white-seeded lines IS 21443, IS 24495 and IS 25017, showed greatest grain mould resistance. Improved lines generally had poorer grain mould resistance than these landraces. However, the best improved lines were comparable in resistance to white-seeded landraces. B58586, IS 14375 and IS 14387 are hard-seeded guinea sorghum lines that can be used as sources of grain mould resistance of West Africa. SP 33316, SP 33349 and GM 15018 are agronomically elite lines that can be used as sources of grain mould resistance for further improvement of white-seeded sorghum for South Asia and other regions

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Not AvailableSorghum (Sorghum bicolor (L.) Moench) is an important dry land crop which is being used for food, feed, fodder and fuel in the semi-arid tropics of the world. Heterosis breeding is an important component in the yield improvement of sorghum. In an effort to improve the parental lines for yield and quality, a number of restorers were developed for diverse uses using different germplasm lines and genetic stocks at Directorate of Sorghum Research, Hyderabad. Sixty such restorers were evaluated for their grain, fodder and sweet sorghum traits over three years (2008-2010) and restorers promising for different traits over C 43 and the specific checks for sweet and forage sorghum were identified. DSRR84 was the most promising restorer for grain yield, fodder yield and sweet sorghum traits. DSRR79, DSRR456 and DSRR460 were promising for grain and fodder yields. The identified restorers can be used in the breeding programs aimed at development of sorghum hybrids for different target traits.Not Availabl

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Not AvailableThe potential yield levels of sorghum, an important crop in the semi-arid regions of the world, are stagnating due to the narrow genetic base of the genotypes utilized in the sorghum improvement programmes worldwide. For utilization of genetic diversity in any crop, adequate genetic characterization of relevant germplasm is a prerequisite. Therefore, we attempted to identify the potential germplasm lines for improvement of yield in a set of 135 germplasm lines belonging to different races. The experiment was carried out in an augmented design during 2002, and in Randomized complete block design (RCBD) for selected lines during 2003. The correlation studies indicated that besides panicle weight, the number of grains/unit length of primary branch and the number of secondary branches/primary branch had significant positive relation with grain yield. IS nos 1259, 5447, 5725 and 2036 were promising for more than one yield component. The study indicated that besides caudatum race, the lines belonging to guinea, kafir and inter-races with them are good sources for different yield components. Genetic diversity and cluster analysis grouped 40 germplasm lines into eight clusters, with maximum inter-cluster distance between clusters II and III. Utilization of the germplasm lines belonging to different clusters in improving yield components is discussed.Not Availabl