Combining ability analysis of maize inbred lines from line x tester mating design under Under stress and under non-stress situations

Abstract:

Thirty maize inbred lines were crossed with five testers in a line × tester mating design to produce 150 experimental hybrids, which, together with 35 parental lines and standard checks, were evaluated under non-stress and managed drought-stress conditions during the early spring season of 2013-14 in a restricted randomized block design with two replications, each genotype being grown in a single 4 m row spaced 75 × 20 cm. Under non-stress conditions the material received recommended agronomic practices and irrigation at 10-12-day intervals, whereas under managed stress irrigation was given only up to 30 days after sowing and withheld thereafter so that stress coincided with flowering and grain filling; a 4 m maize buffer separated the two regimes. Specific combining ability (SCA) variance exceeded general combining ability (GCA) variance for most traits and the GCA/SCA ratios were below unity, indicating the predominance of non-additive gene action. Rajkumar × CML446 Inbredline 18, NK6240 × CI4 Inbredline 12 and NK6240 × CI4 Inbredline 24 among the lines, and HS7 among the testers, were the best general combiners. Under non-stress conditions, (Rajkumar × CML446 Inbredline 3) × HS4, (NK6240 × CI4 Inbredline 12) × HS4 and (Allrounder × HS17 Inbredline 34) × HS7 exhibited significant SCA effects coupled with superior grain yield, recording 27.85 to 38.29 per cent standard heterosis. Under managed drought stress, (Allrounder × HS17 Inbredline 34) × HS7, (NK6240 × HS17 Inbredline 14) × HS7 and (Allrounder × HS17 Inbredline 45) × HS10 recorded 45.06 to 56.30 per cent standard heterosis over the check. These hybrids merit further evaluation in multilocation and large-scale trials before consideration for commercial cultivation.