No abstract

An investigation on assessment of heterosis, combining ability and G×E interaction in respect of ethanol yield and its attributing traits was carried out with 30 test hybrids of sweet sorghum developed by crossing five (5) low-sugar female lines with six (6) high-sugar male lines in Line x Tester mating design during kharif season of 2010 over three locations. The hybrids viz., NSS 1007A × CSV 19SS and RS 1220A × SSV 74 are highly suitable for heterosis breeding as they exhibited significant positive standard heterosis for ethanol yield and its contributing traits. The parents, RS 1220B, CSV 19SS and SSV 74 were found to be good general combiners, while the cross combinations viz., NSS 1007A × CSV 19SS and NSS 1016A × SSV 84 showed good specific combining ability coupled with high per se performance for ethanol yield hence highly suitable for heterosis breeding. Based on stability, the hybrids viz., NSS 8A × SSV 84 and NSS 1007A × CSV 19SS for ethanol yield, juice yield and total biomass were found to be stable with well adaptation to all environments whereas NSS 8A × CSV 19SS showed specific adaptation to favourable environments for the traits like ethanol yield, juice yield, total soluble solids and total sugar index while NSS 8A × SSV 74 showed specific adaptation to unfavourable environments for ethanol yield. The hybrid NSS 1007A × CSV 19SS exhibited high mean, significant positive standard heterosis and sca effects along with bi near to unity and non-significant deviation from regression.

Combining ability is mostly used by breeders to identify and select appropriate parental genotypes to produce the larger progeny of new combinations through their hybridization. The objective of this research was to estimate general combining ability of parents and specific combining abilities of F1 hybrids, to identify suitable parents and hybrids for yield and its contributing traits, fibre quality parameters. Nine genotypes and 20 F1 hybrids derived by crossing the parental genotypes in L x T design were sown in randomized complete block design. The ratio of σ2 GCA/σ2 SCA was smaller than zero for all the characters indicating predominance of non-additive gene action (dominant or epistasis) in the inheritance of investigated traits except lint index. The line × tester interactions made greater contribution to the total variance for most of the traits i.e. boll number per plant, boll weight, lint index, lint yield, micronaire, elongation per cent and seed cotton yield. From this study, it is evident that the genotypes TCH 1716 and L 765 were found to the potential combiners for yield and most of the fibre quality parameters as well. Further, the cross combination GSHV 179 x L 765 was found to be the best for commercial exploitation.

The legume crop Pigeonpea (Cajanus cajan (L.) Millsp.) which has drought tolerance belongs to Fabaceae family under the genus Cajanus. It is mainly cultivated in the semi-arid tropics of Asia, Africa and America. In India, it is widely cultivated as a source of food for proteins, income and for soil improvement in intercropping systems. Natural out crossing leads to significant quality reduction and in turn lead to varietal contamination in redgram. To assess the diversity among nine pigeonpea varieties that are cultivated in Andhra Pradesh, the present investigation was carried out with a genetic fingerprint using 50 polymorphic SSR markers. With an average of 3.68 alleles per marker, a total of 184 alleles were observed. The maximum alleles eight were produced by CcM0481A range of 0.00 to 0.84 with an average of 0.52 was observed with Polymorphic Information Content (PIC). Three clusters were produced in neighbour-joining tree method. The variety LRG-223 was found in separate cluster (cluster I) among the nine varieties, while all other genotypes grouped into another major cluster (cluster II) indicating a distinct back ground of this variety.

An experiment was executed during Kharif 2021 at Regional Agricultural Research Station, Lam, Guntur in randomized block design (RBD) in two replications for estimation of combining ability of the parents and gene effects and also the extent of heterosis using line × tester fashion design. Statistical data were collected on the biometrical observations viz., days to 50% flowering, plant height (cm), number of monopodia/ plant, number of sympodia/plant, number of bolls per plant, boll weight (g), seed index (g), lint index (g), Ginning Out Turn (GOT %), seed cotton yield (kg/ha) and lint yield (kg/ha). The lines GISV298 and SCS1207; the testers, Lam GPC 501 and Lam GPC 355 exhibited positive General Combining Ability (GCA) effects for the traits Ginning Out Turn (GOT%), Seed Cotton Yield (SCY) and Lint Yield (LY) signifying that these were good general combiners. The cross combinations viz., TCH1837/GP117, GISV298/GP274, and SCS1207 / GP117 expressed significant specific combining ability (SCA) effects for Seed Cotton Yield (SCY) and Lint Yield (LY). The cross combination, SCS1207/ Lam GPC 355 was identified as the best hybrid combination with high GCA and SCA for important traits like GOT, seed cotton yield, and lint yield coupled with significant positive heterosis which can be further tested in multi-location testing at the station and all India level.