Effects For Grain Yield Research Articles

Combining ability for yield and it’s contributing traits in wheat under heat stress condition (Triticum aestivum L.)

Six lines and eight crosses were crossed in line x tester fashion to determine the general and specific combining ability variances for yield and yield contributing traits in wheat. The Analysis of Variance indicated that the differences due to crosses were significant for all the characters except protein percent. This indicated the presence of substantial genetic variability among the crosses for these characters. Among the parents two lines (AKAW-4627 and AKAW-4927) and two testers (C-306 and DHTW-60) are found to be good general combiners for yield per plant along with the most of the yield contributing traits. Thus, these parents should be included in further hybridization programme. The highest significant sca effect for grain yield was recorded by the cross AKAW-5023 x WH-7304 followed by AKAW-4627 x C-306, AKAW-4627 x DHTW-60, AKW-1071 x AKW-2862-1, NIAW-34 x AKAW-3717. The crosses AKW-1071 x HTW-11 and PDKV-Sardar x HINDI-62 recorded highly significant sca effects for protein percent and β-carotene content respectively. Among the genotypes AKAW-4627 x C-306, AKAW-4627 x DHTW-60 and AKAW-4927 x DHTW-60 are identified as best combiners for yield and yield contributing traits.

Combining Ability of Early-Maturing Yellow Maize Inbreds under Combined Drought and Heat Stress and Well-Watered Environments

Grain-yield potential of maize (Zea mays L.) is limited by the harsh climatic conditions during dry seasons in the savanna of sub-Saharan Africa (SSA). One hundred and five hybrids derived from diallel crosses involving 15 early-maturing yellow maize inbreds were screened under combined drought and heat stress (CDHS) and well-watered (WW) conditions at four locations representative of the dry savannas of Niger, 2012–2014. The objective of the study was to examine the general combining ability (GCA) effects of the inbred lines and specific combining ability (SCA) of the crosses under CDHS and WW environments, assess yield and stability of the derived hybrids under contrasting environments and investigate inter-relationships among traits of the hybrids under contrasting environments. GCA and SCA effects for grain yield and other measured traits were significant, with preponderance of GCA effects over SCA effects under both the CDHS and WW environments. Inbred ENT 13 possessed positive and significant GCA effects for grain yield under both CDHS and WW environments indicating that the inbred could be used for developing outstanding hybrids with good levels of tolerance to CDHS. This also implied that the inbred line could serve as invaluable genetic resource for introgression of favorable alleles into tropical early-maturing maize populations for accelerated genetic gains from selection for improved grain yield. Hybrids ENT 13 × TZEI 167 and TZEI 157 × ENT 13 were the most stable and among the highest yielding hybrids across research environments. These outstanding hybrids could be tested extensively for commercialization in SSA to improve food security. Plant and ear aspects and days to 50% silking could be combined with grain yield in a selection index for improvement of yield under CDHS without yield penalties under WW environments.

STUDIES ON THE GENETICAL COMPONENTS USING THE TOP CROSS MATING DESIGN IN MAIZE (Zea mays L.)

The field experiments were carried out in two successive summer seasons 2014 and 2015 at the experimental farm of the Faculty of Agriculture, Menoufia University, in El-Raheb, Egypt to evaluate yellow inbreed lines of maize through line x tester analysis. A total of twenty-five (Zea mays L.) yellow S4 lines were used to establish the experiment materials. Two testers of yellow maize were used in this investigation to make all possible line x tester crosses. The two testers used in this study were Giza 658 and Sids 3120. Two check verities were used in this investigation their names are single cross Giza 168 and Giza 176. The most important results For grain yield (ard/fed), twelve, four and eight top crosses gave higher grain yield compared with the highest check Giza 168 under HD, ND and combined data, respectively. The top crosses L3 x T1 and L3 x T2 were the highest values for grain yield under this study. Therefore, the inbred line L3 was useful in maize breeding programs. The inbred lines L3, L4, L9, L11 and L14 desirable significant GCA effects for grain yield (ard/fed). Thirteen top crosses showed significant positive SCA effects for grain yield (ard/fed) under HD, ND and their combined. Also, the top crosses L1 x T2 and L11 x T2 were significant under high plant density. The top cross L3 x T1 was the higher value of heterosis relative to two check varieties for grain weight per ear weight and grain yield. Also, eight top crosses were highly significant heterosis relative to two check varieties for grain yield (ard/fed).

STUDIES ON THE GENETICAL COMPONENTS USING THE TOP CROSS MATING DESIGN IN MAIZE (Zea mays L.)

The field experiments were carried out in two successive summer seasons 2014 and 2015 at the experimental farm of the Faculty of Agriculture, Menoufia University, in El-Raheb, Egypt to evaluate yellow inbreed lines of maize through line x tester analysis. A total of twenty-five (Zea mays L.) yellow S4 lines were used to establish the experiment materials. Two testers of yellow maize were used in this investigation to make all possible line x tester crosses. The two testers used in this study were Giza 658 and Sids 3120. Two check verities were used in this investigation their names are single cross Giza 168 and Giza 176. The most important results For grain yield (ard/fed), twelve, four and eight top crosses gave higher grain yield compared with the highest check Giza 168 under HD, ND and combined data, respectively. The top crosses L3 x T1 and L3 x T2 were the highest values for grain yield under this study. Therefore, the inbred line L3 was useful in maize breeding programs. The inbred lines L3, L4, L9, L11 and L14 desirable significant GCA effects for grain yield (ard/fed). Thirteen top crosses showed significant positive SCA effects for grain yield (ard/fed) under HD, ND and their combined. Also, the top crosses L1 x T2 and L11 x T2 were significant under high plant density. The top cross L3 x T1 was the higher value of heterosis relative to two check varieties for grain weight per ear weight and grain yield. Also, eight top crosses were highly significant heterosis relative to two check varieties for grain yield (ard/fed).

UTILIZATION OF LINE x TESTER ANALYSIS FOR ESTIMATING COMBINING ABILITY FOR SOME NEW YELLOW MAIZE INBRED LINES

In 2018 summer season at Gemmeiza Research Station, eleven new yellow inbred lines were crossed with three testers: two inbred lines Gz.658 and Gm.6052) and one single cross SC 162 according to line x tester design. In 2019 summer season the resulting, 33 crosses and four check hybrids: two single crosses (SC 168 and SC 3084) and two three way crosses (TWC 360 and TWC 368) were evaluated at both of Gemmeiza and Sids experimental Research Stations. Significant and highly significant mean squares due to crosses and the partitions lines, testers and lines x testers were obtained for all studied traits across locations, except testers for grain yield. K2 SCA (non- additive gene effects) were more important than K2 GCA (additive gene effects) for all traits Gm.2, Gm.6, Gm.9 and Gm.35 had desirable values for GCA effects for grain yield. The best cross for SCA effects was Gm. 9 × SC. 162 for grain yield. Five single crosses, (Gm. 2 × Gz 658 (28.956 ard /fed), Gm. 35 × Gz 658 (27.777 ard /fed), Gm. 2 × Gm. 6052 (27.566 ard /fed), Gm. 6 x Gm. 6052 (28.157 ard /fed) and Gm. 35 × Gm. 6052 (28.123 ard /fed) did not significantly out-yielded the highest check SC 168 (27.190 ard/fed), while three- way cross Gm. 9 × SC. 162 (29.74 ard/fed) significantly out-yielded the best check TWC 360 (26.42 ard/fed)

Efficiencies of Heterotic Grouping Methods for Classifying Early Maturing Maize Inbred Lines

The success of a hybrid breeding program is dependent on available heterotic patterns for exploitation of grain-yield heterosis. The efficiency of the assignment of germplasm lines into heterotic groups is a prerequisite for obtaining useful heterotic patterns among germplasm lines. A total of 256 maize hybrids, comprising 244 top crosses, six diallel cross hybrids, and six checks, were grown under Striga infestation, drought, and optimal conditions, from 2015 to 2017. The study determined the combining abilities of the parental inbreds, classified the inbreds into heterotic groups, and compared the efficiencies of the following four grouping methods for classifying the inbreds: specific combining ability (SCA) effect of grain yield; general combining ability (GCA) effects of multiple traits (HGCAMT); SCA and GCA (HSGCA) for yield; and single nucleotide polymorphism-based genetic distance (SNP-based genetic distance (GD)). Significant GCA and/or SCA mean squares were revealed for most measured traits in all test environments. Sums of squares (SS) due to GCA were higher than SCA SS for measured traits in all test environments. The HSGCA, SCA, and SNP-based GD methods identified four heterotic groups, whereas the HGCAMT identified three groups, in all environments. The additive gene effect was preponderant in the inheritance of most measured traits. The efficiencies of the grouping methods varied with the test environments. The HSGCA and SCA methods were the most efficient for grouping in all test conditions. For practical breeding purposes, the HGCAMT and HSGCA methods were recommended under Striga infestation and drought, respectively. The heterotic patterns, which were revealed in this study, were effective for planning hybridization schemes for developing high-yielding, Striga-tolerant/resistant, and drought-tolerant maize hybrids for stressful environments.

Efficiency of indirect selection for grain yield in maize (Zea mays L.) under low nitrogen conditions through secondary traits under low nitrogen and grain yield under optimum conditions

Small-scale maize farmers in sub-Saharan Africa use meager amounts of nitrogen (N) in their maize crops. N use efficient varieties can provide a solution to the problem of low N conditions through efficient N uptake and utilization. The objectives of this study were to i) compare the quantitative genetic parameters of grain yield and secondary traits under different nitrogen levels and ii) assess the efficiency of indirect selection for grain yield under low N stress through yield under optimum N and secondary traits under low N stress in maize. Doubled haploid lines derived from five bi-parental populations were evaluated. Genotype effect for grain yield and secondary traits was significant at all sites. Genetic variance for grain yield was reduced by 17% under moderate N stress and 63% under severe N stress conditions, while genetic variance for days to anthesis and plant height increased under both moderate and severe low N stress. The heritability of most secondary traits was consistently higher than that of grain yield. Correlations of grain yield with plant and ear heights were positive under low N conditions. Despite the reduction in genetic variances under low N conditions, there was genetic variability for grain yield and secondary traits. Direct selection for grain yield under low N rather than under optimum conditions was more efficient for yield improvement under the low N condition. The use of an index of secondary traits could increase the efficiency of improving grain yield rather than selection for only grain yield under low N conditions.

Combining Abilities for Yield and Its Components through Line by Tester Analysis in Maize under Two Plant Densities

The field experiments were carried out in two successive summer seasons of 2014 and 2015 at the experimental farmof the Faculty of Agriculture, Menoufia University, in El-Raheb, Egypt to evaluate yellow inbreed lines of maize throughline x tester analysis.Top crosses were made each of the twenty-five S4 lines and the two testers by hand to give a total of 50 top crosses in2014season. In the second season (2015) two adjacent experiments were conducted under two plant densities. The firstexperimental represented a normal plant density (ND) of 24000 plant/fad., (hills spaced 25 cm apart and one plant/ hill).The second experimental represented plant density (HD) of 30000 plants/fad. (hills spaced 20 cm a part and one planthill). In each experiment the 50 top crosses as well as the two checks hybrids Giza 168 and Giza 176 were grown in aRandomized Complete Block Design with three replications. Performance of inbred lines varied with plant densities.Parental lines L3, L4, L5, L14 and L23 were the best in mean performance and general combining ability effects underthis study. Results indicated that σ² SCA was more important than σ² GCA for all studied traits, plant height at thecombined analysis. Non-additive gene action was more affected by the interaction with environments than the additiveeffects. The top crosses L12 x T2 and L17 x T2 showed desirable significant SCA effects for shortness and the low earplacement under low plant density. Thirteen top crosses showed significant positive SCA effects for grain yield (ard/fad)under HD, LD and combined analysis. Also, the top crosses L1 x T2 and L11 x T2 were significant under high plantdensity. The top crosses (L3 x T1 and L14 x T2) and (L3 x T2) showed significant number of ears per plot and 100-kernelweight relative to two check varieties for the top cross L3 x T1 gave the higher value of heterosis relative to the twochecks for ear weight and grain yield.

Combining Ability Analysis of Maize Inbred Lines in Ethiopia

The study was initiated to estimate combining ability of maize inbred lines and crosses using line by tester analysis. Fifty entries consists 48 F1 single crosses developed from 24 inbred lines and 2 testers using line x tester design and two commercial check hybrids used in the study. The experiment was conducted using alpha lattice design with two replications. Analysis of variance revealed existence of significant genetic variation among genotypes for all studied traits except for plant aspect (PA). Location x entry interaction for most of the traits was not significant which suggests hybrid performance was consistent across tested locations. Line x tester analysis of variance showed that mean squares due to GCA of lines were significant (p< 0.01 or p< 0.05) for all studied traits. Mean squares of tester GCA and SCA were significant for most of studied traits. This indicates that both additive and non-additive gene effects had contributed for the variation of the crosses. However, higher proportional contribution of additive gene action for all studied traits was obtained. Several lines and crosses were identified as good general and specific combiners for yield and yield related traits. Lines L23, L11, L15 and crosses L2xT1, L3xT1, L8xT1, L11xT1, L23xT1 and L13xT2 were found to be good general and specific combiners, respectively. In conclusion, the stated inbred lines with desirable gca effects and cross combinations with desirable sca effects for grain yield and yield related traits could be used as useful genetic material.

Combining Ability of Extra-Early Maize Inbreds Derived from a Cross between Maize and Zea diploperennis and Hybrid Performance under Contrasting Environments

Knowledge of the genetic mechanisms conditioning drought tolerance in maize is crucial to the success of hybrid breeding programs aimed at developing high-yielding cultivars under drought. The objectives of this study were to determine the combining ability of extra-early inbreds, compute the heritability of measured traits, assess the performance of inbreds in hybrid combinations and investigate the associations among traits under drought and optimal conditions. A total of 252 hybrids generated by crossing 63 inbreds to four testers, along with four commercial hybrid checks, were evaluated for 2 years under drought and rainfed conditions. General combining ability (GCA) and specific combining ability (SCA) for the traits were significant. A total of 57.1% and 53.4% of the genotypic sum of squares were attributable to GCA effects for grain yield under managed drought and rainfed conditions, respectively. Hybrids TZdEEI 91 × TZEEI 21 and TZdEEI 55 × TZEEI 13 out-yielded the best checks under drought and optimal conditions by 49.13% and 39.05%, respectively. The most promising hybrids with consistently high grain yield under drought and rainfed conditions, were TZdEEI 54 × TZEEI 13, TZdEEI 91 × TZEEI 21 and TZdEEI 55 × TZEEI 21 and should be further evaluated for possible commercial production in sub-Saharan Africa.

Combining ability and gene action in relation to alloplasmic isonuclear lines in pearl millet [Pennisetum glaucum (L.) R. Br.

The Line × Tester analysis involving two CMS lines with diverse (A1, A4 and A5) cytoplasmic sources and six testers (males) of pearl millet was carried out at JAU, Jamnagar (Gujarat) during Kharif 2018 to identify crosses and good combiners for developing new hybrids to achieve higher yield. The variance due to GCA and SCA showed that the non-additive components were pre-dominant for the expression of days to 50% flowering, plant height (cm), number of effective tillers per plant (no.), ear head diameter (cm), grain yield per plant (g) and Fe and Zn content (ppm) Whereas, additive components were predominant for the expression of days to maturity and ear head diameter (cm). Among the female parents ICMB 96222 were identified as good general combiner for grain yield per plant and some other component traits. Among the male parents J-2597, J-2598 and J-2603 was good general combiner for most of the characters. Among the 36 hybrids, five crosses (ICMA5 95222 x J-2597, ICMA4 95222 x J-2597 ICMA5 96222 x J-2596, ICMA4 96222 x J-2584 and ICMA1 96222 x J-2597) were identified as good specific combiners based on significant and positive sca effect for grain yield per plant.

Combining ability and testcross performance of low N tolerant intermediate maize inbred lines under low soil nitrogen and optimal environments

AbstractLow soil nitrogen (low N) threatens maize production in sub-Sahara Africa (SSA). We examined the mode of gene action conditioning grain yield of intermediate maturing inbreds and evaluated lines in hybrid combinations for high yield, stability and tolerance to low N. Thirty-two sets of inbreds were crossed to three elite testers (87036, 1368 and 9071) to generate 96 F1 hybrids. The testcrosses plus four hybrid checks were evaluated under low (30 kg/ha) and high (90 kg/ha) N environments at three locations for 2 years in Ghana. Significant general combining ability (GCA) and specific combining ability (SCA) effects were detected for grain yield and most measured traits across test environments, indicating that both additive and non-additive gene action governed the inheritance of the traits. GCA effects were greater than SCA effects, indicating that most traits were controlled predominantly by additive gene action and that inbreds with positive significant GCA effects for grain yield and other traits would contribute favourable alleles to progenies across environments. Hybrid CZL 0001 × 9071 possessed high GY, increased EPP, desirable EHT and PLHT and was the highest yielding under each of two research conditions. Significant genetic correlations were observed between GY and PLHT, EPP, EHT, CA and PA implying that improvement of these traits would lead to significant gains in grain yield under low-N conditions. Hybrids CLWN 247 × 9071, ZM523B-29-2-1-1-B*6 × 9071, TZD II 68 × 1368 and P43SCRq Fs100-1-1-8 × 9071 were high-yielding, stable and low-N tolerant and should be tested on-farm and commercialized.

COMBINING ABILITY OF NEWLY DEVELOPED WHITE MAIZE (Zea mays L.) INBRED LINES VIA TOP CROSS ANALYSIS

Twelve newly developed white maize inbred lines were crossed with two testers i.e. SC 128 and SC 131 at Ismailia Agricultural Research Station during 2017 season. In 2018 summer season, the 24 top crosses and two white commercial check hybrids; TWC 321 and TWC 324 were evaluated under two locations (Loc); Ismailia and Mallawy Agricultural Research Stations. The studied traits were number of days to 50% silking (DS), plant height (PH), ear height (EH), ear length (EL), ear diameter (ED), number of rows/ear (RE), number of kernels/row (KR) and grain yield (GY). Mean square due to locations were significant for DS, EL, KR and GY traits. The crosses were significant for all studied traits, except PH trait. Mean square due to lines were highly significant for all traits except PH, EH, and KR. Mean square due to testers were highly significant for EH and GY. Also, mean square attributed to lines x testers interaction were highly significant for all traits except for DS, PH, and RE. The interactions of locations (Loc) with crosses and Loc x lines were highly significant for the studied traits except for PH. The superior inbred line Ism 6007 had desirable general combining ability (GCA) effects for grain yield and yield components. Also, the inbred line Ism 7100 showed better GCA effects for PH, EH, ED, RE and GY traits and inbred line Ism 7094 for earliness and grain yield. The tester SC 128 showed the highest GCA effect for grain yield. The best crosses for specific combining ability (SCA) effects were Ism 6040 x SC 128, Ism 7094 x SC 128, Ism 7169 x SC 128, Ism 7186 x SC 131 and Ism 7259 x SC 131 for grain yield and cross Ism 6007 x SC 131 for earliness, grain yield, and yield components. The non-additive gene effects were more important in controlling all studied traits. Moreover, non-additive gene effects were more interacted by environmental conditions than additive gene effects for all studied traits. The highest mean values and significant of crosses for grain yield (GY) were obtained from the Ism 6040 x SC 128 (37.5 ard/fad.), Ism 6007 x SC 131 (37.0 ard/fad.), Ism 7169 x SC 128 (36.7 ard/fad.), and Ism 7094 x SC 128 (35.5 ard/fad.). These three ways crosses out yielding significant than the commercial hybrids TWC 321 (33.7 ard/fad.) and TWC 324 (32.5 ard/fed). These promising hybrids should be tested in advanced trails.

Variability and path analysis studies in F2 population of sorghum (Sorghum bicolor (L.) Moench)

A field experiment was conducted to evaluate Sorghum (Sorghum bicolor (L.) Moench) F2 population of COS 28 x SPV 2308 and COS 28 x SPV 2307. These crosses were raised during Kharif’2018. Variability and path analysis was carried out for ten morphological traits viz., plant height, days to flowering, the number of leaves, flag leaf length, flag leaf width, panicle length, panicle weight, the number of primaries, 100 seed weight and grain yield per plant. The mean value was found to be higher in COS 28 x SPV 2307 for the traits namely plant height and the number of leaves per plant. The mean value was found to be higher in the cross COS 28 x SPV 2308 for the traits viz., flag leaf length, flag leaf width, panicle length, panicle weight, the number of primaries, 100 seed weight and grain yield per plant. Variability studies revealed that the high PCV was observed in both the crosses for all the traits thus showing high environmental influence except days to flowering and the number of leaves. High GCV, heritability and Genetic advance as percentage of mean was found to be high for the traits namely flag leaf length and flag leaf width in COS 28 x SPV 2308 and for the traits panicle length and the number of primaries in COS 28 x SPV 2307. The traits exhibit high GCV, heritability and GAM are additive in nature which could be used as the selection criteria for increasing the yield potential. Path analysis revealed that both the crosses showed high direct effect for grain yield per plant through the traits viz., flag leaf length, panicle length, panicle weight, the number of primaries and 100 grain weight. Flag leaf length, panicle length and the number of primaries exhibited high indirect effect through the trait panicle weight in both the crosses.

Evaluation of new yellow maize (Zea mays) inbred lines using line × tester analysis

This study evaluated 20 elite yellow maize (Zea mays L.) inbred lines which were crossed as female parents with three different testers as male parents, i.e. Gem. Pop. (Broad genetic base), Single cross 101 and Inbred line 100 represent (Narrow genetic base) at the Experiment Research Station of Moshtohor, Benha University, Egypt during 2014 summer. The resulting 60 top crosses with three commercial check hybrids i.e. SC.155, SC. Pioneer 3080 and TWC.352 were evaluated in a yield trail in two sowing dates during 2015 growing summer season. A randomized complete block design (RCBD) with three replications was used. The data were recorded on days to anthesis (AD), maturity date (MD), leaf area of upper ear (LA), ear length (EL) and grain yield per feddan (GYPF). The results showed that, sowing dates, crosses, lines, testers except for (MD) and line × testers mean squares were significant for all traits. The parental inbred lines (L-4, L-5, L-10, L-12, L-13, L-14 and L-19) possessed high GCA effects for grain yield and (L-6, L-7, L-10 and L-11) possessed high GCA effects for earliness. These lines could be utilized as promising inbred lines in a hybridization programme to develop high yielding and early maturity maize hybrids. The seven crosses (T-1×L-7, T-1×L-13, T-1×L-17, T-2×L-4, T-2×L-5, T-2×L-10 and T-2× L-12) which had out-yielded significantly the best check SC.3080 could be utilized for future breeding work as well as for direct release after confirming the stability of their performances observed in the current study.

Investigation of combining ability and superiority percentages for yield and some related traits in yellow maize using line × tester analysis

Combining ability estimation is an important genetic attribute for maize breeders in anticipating improvement in productivity via hybridization and selection. This research was carried out to investigate the genetic structure of the 27 F1 maize hybrids established from nine lines derived from Maize Research Department and three testers, to determine general combining ability (GCA), determine crosses showing specific combining ability (SCA) and superiority percentages for crosses. Nine lines, three testers, 27 F1 hybrids and two check commercial hybrids (SC162 and SC168) were studied in randomized complete block Design (RCBD) with three replications during 2016. The results of mean squares showed that significant and highly significant for most studied traits (days to 50% tasseling, days to 50% silking, plant and ear height, ear position, ear length, no. of kernels per row, 100-kernel weight and Grain yield). Estimates of variance due to GCA and SCA and their ratio revealed predominantly non-additive gene effects for all studied traits. Lines with the best GCA effects were: P2 (line 11) and P6 (line 21) for grain yield, for testers Gm174 and Gm1021 had significant GCA effects for grain yield. The hybrids P5×Gm1021, P6×Gm1021, P7×Gm1021, P8×Gm1002, P9×Gm1002 had significant and negative SCA effects for grain yield. Crosses P1×Gm174, P2×Gm1002, P5×Gm1021, P6×Gm174, P6×Gm1021, P7×Gm1021, P8×Gm1002, P9×Gm1021 were the best combinations manifested and significant superiority percentages over than check varieties (SC162 and SC168) for most studied traits. Therefore, these hybrids may be preferred for hybrid crop development.
 Abbreviations: GCA general combining ability; SCA specific combining ability

Line × tester analysis of maize grain yield under acid and non-acid soil conditions.

Soil acidity has received less attention than other biophysical stresses such as drought and low N, despite accounting for a considerable reduction in maize (Zea mays L.) productivity in many parts of southern Africa. The line × tester mating design was used to determine the general combining ability (GCA) for grain yield of 14 maize inbred lines and the specific combining ability (SCA) of their corresponding crosses. Thirty‐three single‐cross hybrids were evaluated under acid and optimum soils across 11 environments over three seasons. Across environments, mean grain yield reduction ranged from 11 to 37% due to low pH. Additive gene action was more important than nonadditive gene action for grain yield under both soil conditions. Tester GCA effects were larger for grain yield than GCA effects of lines and SCA effects of crosses for both soil conditions. Tester GCA effects were less sensitive to environmental fluctuations than line GCA effects and SCA effects of crosses. Cross combinations with desirable SCA effects for grain yield were associated with high per se grain yield, which suggests that SCA was a good predictor of grain yield in this study. These crosses consisted of good × good and good × poor general combiners, which indicates that GCA was a good predictor of grain yield. Therefore, priority should be given for yield selection in progenies and hybridization of specific crosses with desirable SCA when breeding acid‐soil‐tolerant maize.

Combining ability and heterosis among sorghum (Sorghum bicolor [L.] Moench) lines for yield, yield-related traits, and anthracnose resistance in western Ethiopia

High-yielding sorghum genotypes with farmer-preferred agronomic traits and durable anthracnose resistance are key drivers of productivity and adoption. The objective of this study was to determine combining ability effects and heterosis of selected sorghum lines for yield, yield-related traits, and anthracnose resistance, to identify superior parents and families for further selection and breeding. Nine selected sorghum genotypes with known resistance to anthracnose were crossed, using a 9 × 9 half-diallel mating design. Parents and F1 families were evaluated across two locations, using a randomized complete block design with three replications. Significant (P < 0.01) genotype, location, and genotype × location interaction effects were observed for most traits and anthracnose resistance, indicating mixed performances of the tested genotypes, allowing for further selection. General combining ability (GCA) and specific combining ability (SCA) effects were significant (P < 0.01) for most traits, including anthracnose resistance, indicating both additive and non-additive gene action underlying inheritance of the studied traits. Parental genotypes such as Bt-623, 210903, 234112, and 226057 showed positive and significant GCA effects for grain yield. Parents 74222, 214852, and 71708 showed negative and significant GCA for anthracnose resistance. The following families: Bt-623 × 210903, Bt-623 × 234112, Bt-623 × Chemeda, Bt-623 × Gemedi, 210903 × 234112, 210903 × 71708, 74222 × 234112, 74222 × 226057, 234112 × 71708, 226057 × 214852 and 226057 × 214852 expressing positive SCA effects for grain yield were identified. The following desirable families were selected: 174222 × 234112, Gemedi × 71708, Bt-623 × 234112, Bt-623 × Gemedi, 226057 × 71708, Chemeda × 71708, and Gemedi × 71708 with negative SCA effect and low anthracnose severity. These are useful sorghum populations for resistance breeding or direct production.

Combining Ability of some White Maize Inbred Lines for Grain Yield and some Other Traits

Fourteen white maize inbred lines derivative from diverse heterotic group by choice in field disease at Sids Agricultural Research Station were used in this study. In 2014 growing season, the fourteen white maize inbred lines were crossed with two testers Sids 7 and Sids 1157. In 2015 season 28 white single crosses and two checks (SC 10 and SC 128) were assess at two locations (Gemmeiza and Sids). Statistics were registered for five traits [days to 50% silking, plant and ear heights (cm.), ear length and grain yield (ard/fad)]. Collective analysis over two locations revealed that mean squares for crosses, lines, testers and lines × testers were significant and highly for all the studied traits, except lines × testers mean squares for days to 50% silking and ear length. Mean squares for crosses × locations interactions were highly and significantly for all the traits studied, except ear length. Mean squares due to lines × locations had significantly and high for days to 50% silking. Testers × locations interactions had highly and significant for all studied traits. The magnitude of σ2 GCA was larger than that σ2 SCA for all traits. For grain yield, two crosses (L7 × Sd 7 and L13 × Sd7) considerably out yielded the best commercial check SC 128. The best GCA effects were obtained from three inbreed lines (L5, L7 and L13) for grain yield. Two top crosses (L1 × Sd 1157 and L11 × Sd 7) had positively significant SCA effects for grain yield.

Combining ability studies in rabi sorghum by using line × tester analysis

Combining ability studies for grain yield and its components was studied using four male sterile lines and twelve testers at Sorghum Improvement Project, MPKV, Rahuri, Maharashtra. The mean squares due to lines, testers and lines x tester were highly significant indicating the presence of variability for most of the characters. Estimates of general combining ability (GCA) and specific combining ability (SCA) variances indicated the predominance of non-additive gene action for most of the characters. The line 104 A, RMS 2010-10A and testers RSR 986, RSR 1012, RSR 1019, RSR 1003 and RSR 955 were observed good general combiner for grain yield and yield contributing characters. The hybrid viz., 104A x RSR 1003, RMS 2010-10A x RSR 1013, RMS 2010-10A x RSR 955, 185A x RSR 1027, 185A x RSR 1020, RMS 2010-24A x RSR 1019, RMS 2010-24A x RSR 1012, 185A x RSR 986, RMS 2010-24A x RSR 1020 and RMS 2010-24A x RSR 986 etc. exhibited with highly significant and positive SCA effects for grain yield which could be exploited for development of hybrids.