Study of the interrelationship of important traits contributing to the resistance of shoot fly in Sorghum bicolor (l.) moench

Vijayalakshmi, K (1993) Study of the interrelationship of important traits contributing to the resistance of shoot fly in Sorghum bicolor (l.) moench. PHD thesis, Andhra Pradesh Agricultural University.

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Investigations on the interrelationships of important traits that contribute to shoot fly (Atherigona soccata Rondani) resistance in sorghum genotypes selected earlier empericaily for shoot fly resistance were carried out at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh, India in the 1991 -92 postrainy and 1992-93 rainy seasons in shoot fly infested and uninfested conditions. The experiment was conducted in completely randomised block design with ten tall and ten dwarf genotypes originating from the same pedigree or pedigrees of related parents. Data recorded on various morphological, agronomic traits and shoot fly resistance parameters (percentage plants with eggs, number of eggs/100 plants, deadheart percentage) were subjected to statistical analyses to estimate mean performance, genetic variances for different traits, the direct and indirect effects of various morphological, and agronomic traits on shoot fly parameters. Emperical selection for shoot fly resistance and grain yield was effective as the tall lines, SPSF 1128 and 1169 and the dwarf lines, SPSF 1170 and 1101 in the postrainy season, and the tall lines, SPSF 1029 and 11 18, and the dwarf lines SPSF 1014 and 1126 in the rainy season showed shoot fly resistance with desirable grain yield. Grain yield under infestation was reduced by 14 per cent in the talls, and 18 per cent in the dwarfs in the postrainy season, while the reduction was 70 per cent in the talls, and 61 per cent in the dwarfs in the rainy season when compared to the yield potential under uninfested condition. The talls were superior (12 per cent in infested and 7 pe cent in uninfested condition) to the dwarfs in the postrainy season. while the dwarfs were superior (25 per cent in infested, and 3 per cent in uninfested condition) in the rainy season. Shoot fly infestation with infestor rowtfish meal technique was extremely high in rainy season and moderate in postrainy season. Heritabilities for various traits and their genetic gains were high under moderate (about 85 per cent deadhearts in the susceptible checks) infestation. The tall genotypes were slightly more vigorous and glossy and had long, broad, and droopier leaves with more dense trichomes and higher ovipositional preference (in postrainy season) than dwarf genotypes. At maturity dwarfs were significantly short compared to tall genotypes while there were no differences in their heights in the early stage of development in both the seasons. Path analyses indicated that selection should aim to reduce drooping depth (perhaps without reducing leaf lengh,tf, and increase glossiness intensity and early plant height in talls to further enhance the levels of shoot fly resistance. In dwarfs, increasing trichome density, glossiness intensity and leaf length (without increasing droopiness or reducing early plant height) would be desirable. However, the correlations and heritability studies indicated that undue emphasis should not be placed on increasing trichome density (in dwarfs) or reducing the leaf droopiness (in talls) to increase shoot fly resistance as this might lead to reduced grain yields. Therefore, the traits shown to be neutral such as glossiness, early plant height and vigour should be given more emphasis in the selection in both talk and dwarf groups. Thus, the study showed the need to have separate selection schemes to breed dwarf (female) lines and tall (restorer) lines in sorghum.

Item Type: Thesis (PHD)
Subjects: Mandate crops > Sorghum
Others > Entomology
Depositing User: Siva Shankar
Date Deposited: 30 Aug 2011 06:09
Last Modified: 30 Aug 2011 06:09
Acknowledgement: UNSPECIFIED
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