Combining Ability and Heterosis for Some Agronomic Traits in Crosses of Maize.

Combining ability analysis was conducted using line x tester design for seven inbred lines of maize which were crossed to three single crosses as testers at Ismailia Agricultural Research Station during 2016 growing season. In 2017 season, 21 crosses in addition to one check hybrid were evaluated at three locations. Highly significant differences were found between the locations for all studied traits. Mean squares due to crosses, their partitions and their interaction with locations were significant or highly significant for all studied traits, except for lines and lines x testers for number of ears/plant and testers for number of rows/ear. The best inbred lines for general combining ability effects were Gz-8093, Gz-8092 and Gz7253 for earliness and Tep-6240 for grain yield. the tester SC 131 was the best general combiner for days to 50% silking toward earliness, grain yield, number of ears/plant, ear length and ear diameter. The cross Gz-8093 x SC131 had the desirable SCA effects for all traits also. The additive gene effects were more important than the non-additive gene effects in inheritance of days to 50% silking, number of ears/plant, ear length and ear diameter while, the non-additive was more important than additive for grain yield, number of rows/ear and number of kernels/row. The nonadditive gene effects were more affected by environment than additive gene effects for all traits except for number of ears/plant. The cross Gz-8093 x SC131 highly significantly outyielded to the TWC 324, suggesting the use of this cross in maize breeding programs.

Section: Genetic Parameterssupporting

confidence: 94%

Combining Ability of White Maize Inbred Lines Via Line X Tester Analysis

Mousa¹,

Mohamed²,

Aly³

et al. 2021

“…The ratio of σ 2 GCA/σ 2 SCA after subtraction the environmental effect of both GCA and SCA variances as estimated according to Singh and Chaudhary (1979) was less than one for all the studied traits, indicating the non-additive gene action played the major role in the inheritance of all the studied traits, therefore selection procedure in the late or advanced generations will be very important to improve these traits. These obtained results are in the same line with those obtained by Abdel-Moneam et al (2009), Attia et al (2013), Ali (2016), Azad et al (2015), Hassan et al (2019), El Hosary (2020), Hemada et al (2020) and El-Shahed et al (2021).…”

Section: Analysis Of Variancesupporting

confidence: 91%

Investigation on Yield Traits and Quality Properties of some Egyptian Cotton Genotypes Treated with Nano Titanium (TiO2)

shahat

Yehia

El-Baset

2021

Eight S7 white maize inbred lines were derived from selfing of S5 inbred lines of two populations, i.e., Giza-2 and IW-469 were chosen to be used as parents of a half-diallel crossing and obtained on 28 F1 crosses, which evaluated along with the 2 check hybrids at Experimental Farm, Faculty of Agriculture, Al-Azhar University, Assiut Branch in 2021 to identify the best parental general combiners and specific combinations to improve maize for earliness and yield. Results manifested that highly significant differences were detected among crosses for all the studied traits. Also, means squares due to GCA and SCA were highly significant for all traits. The ratio of σ 2 GCA/σ 2 SCA was less than one for all traits. The 4 crosses; P1 x P4, P3 x P6, P5 x P6 and P7 x P8 possessed desirable significant positive heterotic effects for increasing grain yield/plant relative to the checks SC-136 and SC-10, and among them the cross P3 x P6, also possessed significant negative desirable standard heterotic effects for tasseling and silking earliness relative to both the check hybrids. The parent P8 possessed significant desirable GCA effects for grain yield and its components with silking earliness. The 14 crosses; P1 × P2, P1 × P4, P1 × P5, P1 × P8, P2 × P3, P2 × P8, P3 × P4, P3 × P6, P3 × P7, P3 × P8, P4 × P5, P5 × P6, P5 × P7 and P7 × P8 possessed significant positive desirable SCA effects for high yielding ability and among them the 2 crosses; P1 × P8 and P2 × P3, also possessed significant desirable SCA effects for tasseling and silking earliness.

“…Both GCA and SCA mean squares were highly significant for all the studied traits, indicating both additive and non-additive gene actions are involved in the inheritance of all the studied traits. These results were in confirmation with Ahmed et al (2008), Abdel-Moneam et al (2009), Osman et al (2012), Attia et al (2013), Abo El-Haress (2015, Bisen et al (2017), Hammadi and Abed (2018), Anees et al (2019), Hussain et al (2019), Hemada et al (2020) and El-Shahed et al (2021). The ratio of σ 2 GCA/σ 2 SCA after subtraction the environmental effect of both GCA and SCA variances as estimated according to Singh and Chaudhary (1979) was less than one for all the studied traits, indicating the non-additive gene action played the major role in the inheritance of all the studied traits, therefore selection procedure in the late or advanced generations will be very important to improve these traits.…”

Section: Analysis Of Variancesupporting

confidence: 77%

Determination of Combining Ability and Type of Gene Action Using Half-Diallel Cross Among Seven S6 White Maize Inbred Lines

El-Zaher

2021

Seven S6 white maize inbred lines were derived from selfing of S4 inbred lines of two populations; three way cross-324 and Giza-2 were used as parents of a 7 x 7 half-diallel cross and were obtained on 21 F1 crosses. These 7 S6 inbred lines and their 21 F1 crosses along with the 2 checks i.e., SC-128 and SC-129 were evaluated at Experimental Farm, Faculty of Agriculture, Al-Azhar University, Assiut Branch in 2021. Highly significant differences were detected among genotypes, parents, crosses, parents vs. crosses, general and specific combining abilities for all traits. σ 2 GCA/σ 2 SCA was less than the unity for all traits. The 4 crosses; P4 x P7, P5 x P6, P5 x P7 and P6 x P7 possessed desirable significant positive heterotic effects for increasing grain yield/plant relative to the checks SC-128 and SC-129, and among them the 3 crosses; P5 x P6, P5 x P7 and P6 x P7, also possessed significant negative desirable standard heterotic effects for tasseling and silking earliness relative to both the checks. The 2 parents; P6 and P7, which derived from Giza-2 population could be considered as good general combiners for improving maize genotypes for earliness and high yielding ability. The 9 crosses; P1 × P2, P1 × P4, P1 × P5, P2 × P6, P3 × P4, P3 × P7, P5 × P6, P5 × P7 and P6 × P7 possessed significant positive desirable SCA effects for high yielding ability, as well as significant negative desirable SCA effects for earliness. The dominance was in over dominance range for all the studied traits, where the average degree of dominance was more than one.