Inheritance of Resistance to Sorghum Shoot Fly, Atherigona soccata in Sorghum, Sorghum bicolor (L.) Moench

Sorghum production is affected by a wide array of biotic constraints, of which sorghum shoot fly, Atherigona soccata is the most important pest, which severely damages the sorghum crop during the seedling stage. Host plant resistance is one of the major components to control sorghum shoot fly, A. soccata. To understand the nature of gene action for inheritance of shoot fly resistance, we evaluated 10 parents, 45 F1's and their reciprocals in replicated trials during the rainy and postrainy seasons. The genotypes ICSV 700, Phule Anuradha, ICSV 25019, PS 35805, IS 2123, IS 2146, and IS 18551 exhibited resistance to shoot fly damage across seasons. Crosses between susceptible parents were preferred for egg laying by the shoot fly females, resulting in a susceptible reaction. ICSV 700, ICSV 25019, PS 35805, IS 2123, IS 2146, and IS 18551 exhibited significant and negative general combining ability (gca) effects for oviposition, deadheart incidence, and overall resistance score. The plant morphological traits associated with expression of resistance/susceptibility to shoot fly damage such as leaf glossiness, plant vigor, and leafsheath pigmentation also showed significant gca effects by these genotypes, suggesting the potential for use as a selection criterion to breed for resistance to shoot fly, A. soccata. ICSV 700, Phule Anuradha, IS 2146 and IS 18551 with significant positive gca effects for trichome density can also be utilized in improving sorghums for shoot fly resistance. The parents involved in hybrids with negative specific combining ability (sca) effects for shoot fly resistance traits can be used in developing sorghum hybrids with adaptation to postrainy season. The significant reciprocal effects of combining abilities for oviposition, leaf glossy score and trichome density suggested the influence of cytoplasmic factors in inheritance of shoot fly resistance. Higher values of variance due to specific combining ability (σ2s), dominance variance (σ2d), and lower predictability ratios than the variance due to general combining ability (σ2g) and additive variance (σ2a) for shoot fly resistance traits indicated the predominance of dominance type of gene action, whereas trichome density, leaf glossy score, and plant vigor score with high σ2g, additive variance, predictability ratio, and the ratio of general combining ability to the specific combining ability showed predominance of additive type of gene action indicating importance of heterosis breeding followed by simple selection in breeding shoot fly-resistant sorghums. Most of the traits exhibited high broadsense heritability, indicating high inheritance of shoot fly resistance traits

Genetic Variability, Genotype × Environment Interaction, Correlation, and GGE Biplot Analysis for Grain Iron and Zinc Concentration and Other Agronomic Traits in RIL Population of Sorghum (Sorghum bicolor L. Moench)

The low grain iron and zinc densities are well documented problems in food crops, affecting crop nutritional quality especially in cereals. Sorghum is a major source of energy and micronutrients for majority of population in Africa and central India. Understanding genetic variation, genotype × environment interaction and association between these traits is critical for development of improved cultivars with high iron and zinc. A total of 336 sorghum RILs (Recombinant Inbred Lines) were evaluated for grain iron and zinc concentration along with other agronomic traits for 2 years at three locations. The results showed that large variability exists in RIL population for both micronutrients (Iron = 10.8 to 76.4 mg kg−1 and Zinc = 10.2 to 58.7 mg kg−1, across environments) and agronomic traits. Genotype × environment interaction for both micronutrients (iron and zinc) was highly significant. GGE biplots comparison for grain iron and zinc showed greater variation across environments. The results also showed that G × E was substantial for grain iron and zinc, hence wider testing needed for taking care of G × E interaction to breed micronutrient rich sorghum lines. Iron and zinc concentration showed high significant positive correlation (across environment = 0.79; p 0.60, in individual environments) for Fe and Zn and other traits studied indicating its suitability to map QTL for iron and zinc

Phenotyping for Plant BreedingApplications of Phenotyping Methods for Crop Improvement /

XI, 211 p. 14 illus., 12 illus. in color.online r

Field Technique and Traits to Assess Reproductive Stage Cold Tolerance in Sorghum (Sorghum bicolor (L.) Moench

Post-rainy season sorghum (Sorghum bicolor (L.) Moench) yields are often constrained by cold stress. Cold tolerance is a prerequisite for adaptation to post-rainy season. A study was conducted to develop a field screening technique for cold tolerance, and to identify traits that discriminate genotypes to cold response. A set of rainy and post-rainy season adapted sorghum genotypes were sown in 2010 – 2011 and 2011 – 2012 in 3 dates of sowing in post-rainy seasons from third week of October to second week of November. The average minimum temperature during a 30-day period after the initial 40-day vegetative growth was lower in October sowing, moderate in November sowing and high in December sowing. The panicle harvest index (PHI) was found to be sensitive to low temperatures and was identified as a stable trait for genetic discrimination. Reduction in PHI can be indicative of failure to set seed or poor grain filling. The genotypes bred for rainy season ICSB 52, ICSR 149 and ICSR 93034 exhibited reduced PHI and lighter seed in cold-prone environments, indicating that their sensitivity is also well reflected in the yields of ICSB 52 and ICSR 149. However, the genotypes bred for post-rainy season, Dagadi solapur, SPV 1411 and M 35-1, were not affected by cold, as indicted by their higher PHI and relatively less reduction in seed weight. It was suggested that PHI and seed weight together can be used as proxies in selecting for reproductive stage cold tolerance in sorghum

Components of resistance to sorghum shoot fly, Atherigona soccata

Sorghum shoot fly, Atherigona soccata is one of the major constraints in sorghum production, and host plant resistance is one of the components to control sorghum shoot fly. Thirty sorghum genotypes were evaluated for different mechanisms of resistance and morphological and agronomic traits during the rainy and postrainy seasons. The sorghum genotypes, Maulee, Phule Anuradha, M 35-1, CSV 18R, IS 2312, Giddi Maldandi, and RVRT 3 suffered lower shoot fly damage, and also exhibited high grain yield potential during the postrainy season. ICSB 433, ICSV 700, ICSV 25019, ICSV 25022, ICSV 25026, ICSV 25039, PS 35805, Akola Kranti, and IS 18551 exhibited antixenosis for oviposition and antibiosis against sorghum shoot fly, A. soccata. Leaf glossiness, plant vigor, leafsheath pigmentation and trichomes were associated with resistance/susceptibility to shoot fly. Path coefficient analysis indicated that direct effects and correlation coefficients of leaf glossiness, plant vigor, plant height, plant color and trichomes were in the same direction, suggesting that these traits can be used to select sorghum genotypes for resistance to shoot fly. Principal co-ordinate analysis based on shoot fly resistance traits and morphological traits placed the test genotypes into different groups. The genotypes placed in different groups can be used to increase the levels and broaden the genetic base of resistance to shoot fly. The environmental coefficient of variation and phenotypic coefficient of variation for shoot fly resistance and morphological traits were quite high, indicating season specific expression of resistance to sorghum shoot fly. High broadsense heritability, genetic advance and genotypic coefficient of variation suggested the predominance of additive nature of genes controlling shoot fly resistance, suggesting that pedigree breeding can be used to transfer shoot fly resistance into high yielding cultivars. This information will be useful for developing shoot fly-resistant high yielding cultivars for sustainable crop production