Genetic variability for forage yield and nutritive quality characteristics in selected inbred x Triticosecale genotypes

[摘要] English: The objective of this study was to study the combining ability, heritability and additivegenetic correlation of various nutritive quality, forage yield and animal productioncharacteristics in a selected fixed population of triticale genotypes.The vegetative matter obtained from two sequential cuts per plot was used forchemical analyses and the calculation of plant production and animal production. Thetrial was a split-plot in time experiment planted in a randomised block design. Threereplications were planted and the plots were made up of three rows each.Characters measured for forage quality in both cuts were NDF, ADF, ADL,hemicellulose, crude cellulose, NDFadj, EE, NSC, IVDOM, ME and MRT. Charactersused for plant production were kg DM/ha, crude cellulose yield/ha, EE yield/ha,NSC yield/ha, IVDOM yield/ha and ME yield/ha. Characters used for animalproduction were DM Intake/steer/day, ME Intake/steer/day, LWG/steer/day and Liveweight gain/ha. Each one of the animal production characters were calculatedaccording to three different feed intake models.Significant differences were shown in cut 1 between genotypes for NSC, EE and allfibre characters except hemicellulose and crude cellulose. Significant differenceswere shown in cut 2 for NSC, ME and MRT. Significant differences were shown inboth cuts for all the plant production characters. Highly significant differences wereshown in cut 1 for Live weight gain/ha according to all three different intake models.The F1 progeny of a 6 x 6 half diallel cross were evaluated in the combining abilityanalyses using the Method 4, mixed model B analysis of Griffing (1956b), becauseonly one reading per plot was obtainable for each of the characteristics measured.In the combining ability analyses of the F1 progeny, significant differences wereshown in cut 1 for gca effects of EE and all fibre characters except hemicellulose.Significant differences were shown in cut 2 for EE, IVDOM, ME and MRT. Significantdifferences were only shown in cut 1 for all the plant production characters. Highlysignificant differences were shown in cut 1 for Live weight gain/ha according to allthree different intake models.The levels of relative high parent heterosis did not warrant the forming of hybrids inan effort to increase Live weight gain/ha.The σ2 gca/σ2 sca and h2n were moderately high for NDFadj, kg DM/ha and Live weightgain/ha in cut 1 and moderate for MRT in cut 2. Highly significant additivecorrelations were found between IVDOM yield/ha and Live weight gain/ha accordingto all three different intake models in cut 1. A significant negative additive geneticcorrelation was found between kg DM/ha in cut 1 and IVDOM in cut 2.Recommendations were given for the identification of breeding parents, selection inthe early generations as well as the final evaluation in order to select a new cultivarfor registration.

[发布机构] University of the Free State