Significant SCA Effects Research Articles

Combining ability and heterosis studies for seed cotton yield and fibre quality traits in hirsutum cotton

Fifty intra hirsutum hybrids developed by involving five female and ten testers were evaluated to study gene action, combining ability and heterosis. The analysis of variance indicated substantial variability among the experimental material for yield, its contributing components and fibre quality traits. Preponderance of non-additive gene action was obtained for seed cotton yield per plant, majority of its component traits and fibre quality traits. Three parents namely TSH 321, BGDS 1055 and GSHV 177 were identified as very good general combiners for yield and fibre quality traits. The cross combinations TSH 321 x African I-2, and CCH 15-1 x GSHV 177 for seed cotton yield per plant and fibre properties whereas the crosses BGDS 1055 x GSHV 177, TSH 321 x TCH 484-4, SHM 55 x TCH 1819 for seed cotton yield per plant and number of bolls per plant were identified as the best hybrids and these are well suited for exploitation through heterosis breeding as it recorded significant per se, sca effects and standard heterosis for trait as mentioned. Further, the crosses namely SHM 55 x CNH 19, SHM 55 x GSHV 177 and SHM 55 x TCH 486-7 could be recommended for recombination breeding as they satisfied the criteria of the presence of significant gca effects of the parents and non significant sca effects for yield and fibre quality traits. The study also revealed good scope for commercial hybrid development as well as isolation of pure lines among the progenies.

Studies on combining ability of new restorer lines in sunflower (Helianthus Annuus L.)

The present investigation was undertaken to assess the combining ability of parents and also to estimate the extent of heterosis for eleven different characters in 40 hybrids which were derived by crossing four CMS lines with ten testers in a line x tester mating design during kharif 2015. The resultant hybrids and parents along with standard checks, LSFH-35 and LSFH-171 were evaluated for seed yield and yield contributing traits. CMSPET 89-1A and CMS PET 2-7-1A, were good combiners for seed yield and oil content, respectively. Two restorers RHA138-2, EC 601957 were found to be the best general combiners for yield and other yield contributing traits. The best cross combinations, PET 2-7-1A x EC 601957, CMS 234A x EC 601924, PET 2-7-1A X R-16 and ARM 249A x R 271-1 for seed yield per plant with high significant sca effect and heterosis have been identified.

Combining ability studies for yield and quality parameters in basmati rice (Oryza sativa L.) genotypes using diallel approach

General and specific combining ability of six basmati rice varieties and their fifteen hybrids made through diallel mating without reciprocals for different yield and quality parameters were studied to select the general combiners for future domestic breeding programs. The Analysis of Variance showed that the mean squares due to general and specific combining ability were highly significant for all the traits indicating that both additive and non-additive gene actions were involved in the inheritance of fourteen yield and quality traits. Significant SCA effects for different characters indicated preponderance of non-additive gene actions in the inheritance of the characters under study. Different lines and hybrids were found as best general and specific combiners for different yield and quality traits, respectively. Thus, important specific cross-combiners can be used effectively in crop improvement programs to develop varieties, and further validation of specific genes to develop gene-based perfect markers in rice breeding.

Combining ability analysis for yield and its components in bread wheat (Triticum aestivum L.)

Combining ability was analyzed using a line × tester (8 × 4) analysis in bread wheat (Triticum aestivum L.). Combining ability analysis, revealed the importance of both additive as well as non-additive genetic variances for control of various traits. The potence ratio (σ2gca/ σ2sca) suggested the preponderance of additive gene actions for number of effective tillers per plant, length of main spike, number of spikelets per main spike, number of grains per main spike and 100-grain weight and non-additive gene actions for rest of the traits. Parent MP 3288 was the best general combiner, whereas crosses MP 3288 × GW 496 and MP 3288 × GW 366 were found to be the best specific combiners for grain yield per plant and some of the yield contributing traits. However, on the basis of per se performance and significant SCA effects for grain yield per plant and some of its important components, hybrids MP 3288 x GW 366, MP 3288 x HI 1544 and GW 173 x GW 451 were considered to be the most promising for further exploitation in breeding programmes.

Combining ability studies on resistance to pink stem borer (Sesamia cretica) in new yellow maize (Zea mays) hybrids

Maize (Zea mays L.) is the third most important staple crop in Egypt. Sesamia cretica (S. cretica), the most prevalent corn borer in Egypt attacks young maize plants after emergence, causing death of these plants (dead hearts) and its capable of damaging older plants causing drastic yield losses. This study was carried out at the Experimental Research Station of Moshtohor, Benha University, Al-Qalyubiyah Governorate, Egypt during the two successive seasons 2014 and 2015. A half diallel cross between nine yellow inbred lines of maize (Zea mays L.) was evaluated in under two environments i.e. (under borer artificial infestation conditions and normal conditions) in RCBD with three replications to estimate the combing ability and the interaction of hybrids under the artificial infestation. Artificial infestation was done by newly hatched larvae of the pink stem borer S. cretica. Highly significant crosses mean squares were detected for all the studied traits indicating the wide diversity between the parental materials used in this study. General and specific combining ability (GCA and SCA) were significant for all the studied traits except SCA for days to 50% tasselling and ear height at the infestation condition. The parental inbred line P6 and P9 were considered as good combiners for grain yield under infestation and non-infestation conditions as well as the combined over them. Six crosses i.e. (P1×P6, P1×P7, P2×P4, P3×P5, P5×P7, and P8×P9) exhibited positive significant SCA effects (favourable). Therefore, they could be utilized for future breeding work as well as for direct release after confirming the stability of their performances across different environments.

Heritability, genetic gain and detection of gene action in hexaploid wheat for yield and its related attributes

Selection of promising genotypes from a diverse genetic pool and their utilization for hybridization is an important strategy for wheat crop improvement. The data from ten parents and their F1 progenies using line × tester mating scheme were analyzed to assess the effects of combining ability for yield and its cognate characters using randomized complete block design with three replications. Data were taken for grain yield and its associated characters like plant height, peduncle and spike length, flag leaf area, per plant tillers, spikelets spike−1, grains spike−1, spike density, thousand-grain weight and grain yield plant−1. Analysis of variance was used to statistically analyze the data. Line × tester analysis was used to find out association among traits and to estimate the effects of GCA and SCA. Highly significant differences were found among parents (lines, testers) and their F1 hybrids for all the parameters under study. Among parents, Line 9796 and tester 107 manifested as best general combiners and exhibited significant GCA effects for almost all the mentioned traits. In the case of F1 hybrids, 9793 × 118 and Punjab-2011 × 108 were recognized as best specific combiners exhibiting significant SCA effects. A higher value of SCA variance than the variance of GCA revealed the preponderance of non-additive genetic action. The degree of dominance revealed the involvement of both type of gene action for the traits under investigation. The deviations among total variation were mainly due to genotypes. Most of the yield associated traits were highly heritable with more than 80% heritability. These findings were confirmed by genetic gain. Thus, potential homozygous lines can be selected from transgressive segregants to improve yield and these crosses will be beneficial for commercial exploitation to heterosis.

GENE ACTION AND HETEROSIS OF MUSKMELON

Six parental genotypes namely 673 (P1), 3M-637-D (P2), 3M-673-EB (P3) , 86E2143(P4), 86E2147 (P5) and WA20 (P6) representing wide range of variability in most of the studied traits,were employed and crossed in half diallel fashion. This investigation was carried out at theExperimental Farm of Ismailia Agriculture Research station, Ismailia Governorate, Egypt, during thethree summer seasons of 2015, 2016 and 2017, to study the important economical traits of muskmelonas fruit width, fruit length, flesh thickness, cavity diameter, total soluble solids, ascorbic acid content,carotenoids content, fruit weight, total yield/vine and fruit number/vine. A greater ratio of GCA/SCAthan unity was detected for most studied traits, revealing that the inheritance of these traits was mainlycontrolled by additive gene effects. On the contrary, both TSS and ascorbic acid content traits, nonadditivetype of gene action seemed to be more prevalent. The maximum significant MP heterosis indesirable direction (112.4%) was recorded for ascorbic acid followed by total yield/vine (101.0%),number of fruits per vine (100%), TSS (65.3%), flesh thickness (62.1%), fruit weight (59.8%) andfruit length (53.6%). Heterobeltiasis (over the best parent better, BP) was observed and the maximumsignificant manifestation was orderd as: Ascorbic acid (108%), number of fruits per vine (69.4%),both TSS (%) and cavity diameter (58.8%) and total yield per vine (49.8%). The cross 3M-637-D (P2)x 86E2143 (P4) was derived from low x high general combiner parents for total yield/ vine andexhibited the highest mean yield, highest heterosis, highest SCA effects for yield. It showed also,significant or highly significant desirable SCA effects for eight important traits.

Estimation of Heterosis Combining and Ability in Faba Bean (Vicia faba L.) by Line X Tester Technique

The present study was conducted at Sakha Research Station during 2014/2015 and 2015/2016 growing seasons. Line x Tester analysis was used, five lines and four testers were crossed in all possible cross combination according to factorial mating design producing twenty hybrids of Faba Bean in the first season. All genetic materials were tested under two sowing dates, i.e. October 20 (early date) and November 20 (late date) each in one experiment arranged in a randomized complete block design with three replications in the second season. Results revealed highly significant variations within parents and F1 genotypes indicating a wide genetic variability for the studied characters and the possibility of genetic improvement using such genetic pools of faba bean. Regarding yield and its components traits, the most crosses exhibited significant positive heterosis values relative to better parent for total dry seed yield, three, six and four crosses exhibited significant positive heterotic effects relative to better parent for number of seeds/plant, seed yield/plant and 100-seed weight respectively, under the two sowing dates. Both general (GCA) and specific (SCA) combining ability were significant for the most studied characters revealing the important role of both additive and dominant components in the inheritance of the studied characters. The parental genotype (Giza716) was a good combiner for seed yield/plant and100-seed weight under the two sowing dates. Several crosses exhibited significantly positive SCA effects for the most studied characters especially the crosses (Sakha 4 x Qahera 4, Cross 957 x Giza 843 and Giza 716 x Qahera 4) and the crosses (Sakha1 x Misr 1, Sakha 4 x Misr 1 and Giza 40 x Giza 843) which exhibited highly significant and positive SCA effects for seed yield/plant and 100-seed weight respectively under the two sowing dates. Heritability in broad sense estimates (Hb %) were higher than their corresponding of narrow sense heritability (Hn %). The estimates of narrow sense heritability ranged were (37.7-40.4 %), (33.7-46.8 %) and (45.5-48.3 %) for number of seeds/plant, seed yield/plant and 100-seed weight, respectively under the two sowing dates.

Combining ability for some inbred lines in half-diallel crosses of maize under two different locations conditions

A half diallyl cross among eight new yellow maize inbred lines, i.e. Gm. 142, Gm. 224, Gm. 233, Gm. 152, Gm. 297, Gm. 330, Gm. 201, and Gm. 303, was made in 2015 summer season. Twenty eight F1 crosses along with two yellow commercial check hybrids, SC162 and SC168 were evaluated in randomized complete block design with four replications at two locations (Gemmeiza, Gharbia and Sids, Bani Sweif, Egypt) in 2016 summer season to study the combining ability to identify the most superior parental inbred lines that produce superior hybrids and develop high yielding new yellow single crosses. Results indicated that mean squares of crosses exhibited significant or highly significant for all studied traits. Mean squares due to GCA and SCA were significant or highly significant for all studied traits at combined over the two locations, except GCA for ear diameter trait and SCA for ear length trait, which were non-significant. The ratio of GCA/SCA was more than unity for all studied traits at combined over the two locations, except days to 50% silking and ear diameter traits, indicating that additive gene was more important than non-additive gene action. The interaction between GCA and SCA and locations were highly significant for all studied traits, except GCA x Loc. for ear diameter trait and SCA x Loc. for ear length trait. The magnitude of the interaction was highest for GCA × locations than the SCA × locations for plant height, ear height, ear length and grain yield, indicates that additive genetic variance was influenced by environment and the additive component interacted more with the environment than the non-additive and vice versa for days to 50% silking and ear diameter. According to analysis of GCA effects, the best general combiners were P3 (Gm.233) for earliness; P4 (Gm.152), P5 (Gm.297), P6 (Gm.330) and P7 (Gm.201) for plant height (shortness); P5 (Gm.297), P6 (Gm.330) and P7 (Gm.201) towards lower ear position; P4 (Gm.152) and P6 (Gm.330) for ear length; P1 (Gm.142) for ear diameter; and P1 (Gm.142), P5 (Gm.297) and P8 (Gm.303) for grain yield. Based on mean performance and SCA effects analysis, there were seven crosses No. 1, 2, 5, 7, 9, 25 and 26 (P1 x P2, P1 x P3, P1 x P6, P1 x P8, P2 x P4, P5 x P8 and P6 x P7) were the best combinations where they recorded significant or highly significant positive SCA effects for grain yield.

Heterosis and combining ability in small fruited ash gourd (Benincasa hispida)

An attempt was made to develop small fruited ash gourd [Benincasa hispida (Thunb) Cogn] hybrids by crossing 10 genetically diverse ash gourd genotypes in a diallel mating system. The 45 F1 hybrids along with their parents were evaluated for assessing their heterosis and combining ability for 11 important economic traits. The parent P2 (Elevenchery local) was the best general combiner for fruit yield and fruits/plant. The specific combining ability component of variance (∂2s) was higher than general combining ability component of variance (∂2g) for the all the 11 characters studied which indicated the predominance of non-additive gene action in the improvement of these characters. The hybrids, viz. P2 × P7 (Elevenchery local × Chengamanad) which exhibited the highest heterosis over top parent (79.95 %) and highly significant sca effects for fruit yield, fruit length, flesh thickness, average fruit weight and days to first fruit harvest followed by P3 × P4 (Malappuram × IC 392313) which recorded the highest heterosis over better parent (166.38%) and highly significant sca effects for fruit yield, fruits/plant, flesh thickness and fruit length were found promising. Both the hybrids were small fruited with average fruit weight (2.04 kg) and (1.65 kg) respectively.

Gene Action and Combining Ability for Seed Yield and its Components in Eight Sesame Genotyps Diallel Crosses

In order to study the combining ability, type of gene action and partition the components of the genetic variance to its constituents of additive and dominance gene effects using half diallel cross for eight genotypes to produce twenty eight sesame crosses. Two field experiments were carried out during two summer growing seasons 2016 and 2017 at Arab El-Awammer Research Station, Assuit, Agricultural Research Center. Results showed that mean squares due to both general (GCA) and specific (SCA) combining ability were highly significant for all characters, indicating the importance of both additive and non-additive gene effects in the inheritance of studied traits. The ratio of GCA/SCA indicated that the largest part of the total genetic variability due to the additive and additive x additive was very important than the non-additive gene effects in the genetic variability for all studied traits. Estimates of GCA for eight parents revealed that P8 was good combiner for plant height, length of fruiting zone, seed yield/plot and number of days to 50% flowering, while P1, P2 was good combiner for number of capsules/plant, seed yield/plant and 1000-seed weight. Significant SCA effects were observed for some crosses, cross (P1xP5), (P1xP7) and (P2xP3) were the best ones for seed yield/plant. Additive D and dominance (H1 and H2) genetic variation were significant for plant height and seed yield/plot. The D parameter estimating the additive effect was highly significant and was larger in magnitude than the dominance parameters (H1 and H2) in the all studied traits indicating that the type of gene action is partial dominance. The positive and negative alleles were unequally distributed among the parents. All studied traits had a high values for the broad sense than the narrow sense heritability. Graphical analysis revealed that the regression lines cuts Wr axis above origin point, indicating partial dominance for all the studied characters.

English

Utilization of stress tolerant maize is key to sustainable production and food security. Limited knowledge on genetics of drought tolerance hampers development of drought tolerant varieties. The aim of this study was to study inheritance and combining ability of drought tolerance and grain yield among early inbred lines of maize. Five inbred lines were mated in full diallel in 2015 major season. The resultant 20 hybrids, 5 parents and 2 checks were evaluated under drought stress and well watered conditions in a screen house. Data was collected on days to 50% tasseling (DT 50%), days to 50% silking (DS 50%), anthesis-silking interval (ASI), leaf rolling, leaf senescence, plant aspect (PASP), plant height (PHT), ear height (EHT), ears per plant (EPP), ear weight, hundred grain weight (100 GW) and grain yield per hectare (GY). Drought condition was induced 40 days after planting (DAP) but watering was continued once per week till maturity. Results from combined ANOVA showed there was high and significant (p<0.01) level of genetic variability among parental lines and hybrids used in all the traits studied except DT 50%, PHT, EHT, EPP and 100 GW. Both additive and non-additive gene actions were important as well as GCA/SCA ratio variance. Lines TZEI-23 (215.22) and TZEI-25 (76.84) had the highest and highly significant (p<0.01) positive GCA effects for GY under drought. Hybrids TZEI-25 x TZEI-13 showed the highest positive and highly significant (p<0.01) SCA effects for GY (385.74) followed by its reciprocal TZEI-13 x TZEI-25 (311.49) under water stress. High broad sense heritability was observed for almost all the traits. High narrow sense heritability were observed DT 50% (0.69), DS 50% (0.80) and leaf senescence (0.61) under drought condition. Eighteen and nineteen hybrids had positive high parent heterosis (HPH) under water stress and well watered conditions, respectively for GY. The parents TZEI-23 and TZEI-25 were identified as the best general combiners respectively under drought and well watered conditions. The highest HPH were observed in many traits for TZEI-13 x TZEI-25 and TZEI-124 x TZEI-13. It is recommended these hybrids are further evaluated in different environments for release to farmers to increase yield. Key words: Maize, inheritance, combining ability, drought, tolerance.

Stability factor and heterosis for yield and yield determinants over environments in Indian rapeseed, Brassica rapa var. yellow sarson

Forty-four yellow sarson hybrids developed by line x testers mating design (3 pistillate lines x 9 male parents) were studied along with parents and a standard check for heterosis of yield determinant characters in two environments [Genetics and Plant Breeding Farm (E1), Kumarganj and CRS, Masodha (E2)]. Significant desired heterobeltiosis ranged from 4.52 to 44.86 per cent in E1 and 13.42 to 62.07 per cent in E2 while, standard heterosis ranged from -6.64 to 23.01 per cent in E1 and -6.30 to 21.85 per cent for seed yield plant-1 . Other characters also showed considerable heterosis over better parent and standard check. The crosses L2 x T1 and L3 x T1 were identified as potential for commercial exploitation of heterosis both for seed yield plant-1 and oil content. High heterotic hybrids in both the environments viz., L8 x T1 and L9 x T1 showed stability in performance for nine characters including seed yield plant-1 where as among parent NDYS-141 showed near unity ratio of stability factor for five characters. L9 x T1 followed by L8 x T1 could be identified as most promising crosses on the basis of stability, per se performance, standard heterosis, high GCA and significant SCA effects.

English

Flower thrips [Megalurothrips sjostedti (Trybom)] is the most damaging insect pest on cowpea. However, information regarding the nature of gene action governing the inheritance of resistance to thrips is not available for cowpea genotypes in Uganda. This study was carried out to determine the inheritance pattern of cowpea resistance to flower thrips. Five resistant cowpea genotypes and three susceptible genotypes were crossed in full diallel mating design. F2 progenies were evaluated along with the parents in alpha lattice design with two replications under natural thrips infestation at Kabanyolo, Arua and Serere in Uganda. Combining ability analysis was performed using method one and model one of diallel analysis. The results showed that the environmental effects were highly significant (P<0.001). Additive, dominance and epistasis effects had major contributions. The broad sense heritability varied from 18 to 42% for thrips damage scores and from 0 to 6% for thrips counts. The estimates of narrow sense heritability were low for thrips damage score (2 to 18%) and thrips counts (0 to 9%). Genotypes TVU-1471 and TVU-1509 were identified as good transmitters of resistance to flower thrips. Crosses TVU-1509 x NE5, TVU-473 x Sanzi, TVU-123 x Sanzi, TVU-123 x TVU-473, and TVU-473 x TVU-1509 presented significant (P<0.05) and negative SCA effects for thrips damage scores and thrips counts and would be the most useful in breeding as some of their progenies would have high resistance to flower thrips. This study provides the basis of an efficient breeding program of cowpea for flower thrips resistance. Key words: Damage score, gene action, Megalurothrips sjostedti, Vigna unguiculata.

Study of combining ability analysis for seed cotton yield, yield contributing and fibre quality traits in Desi cotton (Gossypium arboreum L.)

The present investigation entitled “Study on heterosis and combining ability for yield, its components and fibre characters in Desi cotton ( Gossypium arboreum L.)” was undertaken to estimate general combining ability effects (GCA) of the parents and specific combining ability effects (SCA) of the crosses. The experimental material comprised of 24 F 1 hybrids obtained by crossing 4 lines with 6 testers in line x tester mating system. Sum total of 36 treatments consisting of 24 crosses, 10 parents and three standard checks were sown in Randomized Complete Block Design. The analysis of variance for combining ability revealed significant general combining ability effects (GCA) and specific combining ability effects (SCA) for all the traits. Among ten parental lines, most of the lines were found to be best general combiner, which had significant general combining ability (GCA)effect for seed cotton yield and its contributing characters including fibre quality traits. Analysis of variance for means revealed significant differences for all the eighteen characters studied. Among females, PA 741 was found to be the best general combiner for 3 characters viz ., days to 50 per cent flowering, days to 50 per cent boll bursting and days to maturity had significant GCA effects. The female PAIG 77 was the best general combiner for three characters viz ., number of bolls per plant, number of seeds per plant and boll weight. The female PA 809 was the best general combiner for 2.5 per cent span length, fibre fineness/micronaire, fibre strength, uniformity ratio and short fibre index. Among males, AKA 2004-29 found to be best general combiner for days to 50 per cent flowering, days to 50 per cent boll bursting, days to maturity and ginning outturn. Male parent ARBAS 1301 was also found to be best general combiner for number of sympodia per plant, number of bolls per plant,number of seeds per boll, seed cotton yield per plant, lint index, seed index, plant height, 2.5 per cent span length, fibre fineness, short fibre index and fibre strength. Male parent GAM 162 found to be best genral combiner for ginning outturn, 2.5 per cent span length and short fibre index whereas, CNA 1016 for boll weight. There was close agreement between per se performance and GCA as well as SCA effects for most of the characters. Observations on various characters indicated that the crosses showing high heterosis and high SCA effects had high per se performance and they involved at least one high combining parent. The combinations PAIG 77 x ARBAS 1301, PA 734 x ARBAS 1301, PA734 x CNA 1016, PA 809 x ARBAS 1301 and PA 741 x JLA 0614 showed significant and desirable SCA effects for most of the yield and fibre quality traits studied, indicating potential for exploiting hybrid vigor in breeding programme.

Genetics of green pod yield in table pea (Pisum sativum L. Hort.)

An experiment consisting 45 F 1 s derived from ten pea varieties/strains i.e. AP-2, AP-4, AP-5, AP-1, KS-185, KS-218, KS-601, KS-701, KS-801 and AP-3, during the rabi season of 2014-15were raised in crossing block and all possible combination excluding reciprocals were made to obtained 45 crosses. The crosses were evaluated at Vegetable Research Farm, Kalyanpur, Kanpur during Rabi of 2015-16. The analysis of variance for combining ability showed significant differences both for GCA and SCA variances. The estimated values of σ 2 GCA were higher than σ 2 SCA for number of fertile branches per plant, pod width, number of pods per plant, seed-shell ratio and protein content indicated the more contribution of additive genetic variances for controlling these characters. Higher estimates of σ 2 SCA than σ 2 GCA for green pod yield, pod length and number of seeds per pod indicated the role of non additive genes for controlling these traits. Parents AP-1, AP-3, AP-4, KS-601 and KS-701 were found good general combiners for majority of the characters under study including green pod yield per plant. Cross combinations namely; AP2 x AP3, AP2 x KS801, KS218 x KS601, AP4 x AP1, KS801 x AP3, AP4 x KS701, KS185 x KS218, KS185 x KS601, KS701 x KS801and AP4 x KS601 were the top ten crosses which showed higher mean values and significant SCA effects for green pod yield and some other characters under study. Significant contribution of non additive genes were observed for controlling the green pod yield, pod length and number of seeds per pod while additive genetic effects were found effective for controlling the expression of pod width, number of pod per plant, seed-shell ratio and protein content.

Combining ability and gene action for yield traits in greengram [Vigna radiata (L.) wilczek

The combining ability analysis of 225 F3s in greengram developed from half diallel crosses among six parents revealed importance of both additive and non-additive gene actions in the inheritance of pods per plant, seeds per pod, 100-seed weight and yield per plant. There were significant differences in gca and sca effects for the characters studied. OGG-12 was the best general combiner for pods/ plant and grain yield per plant where as OGG-57 was for seeds/ pod, OGG-12 and LGG-460 for 100-seed weight. Among the 15 crosses, six crosses showed significant positive and seven crosses had significant negative SCA effects for seed yield/plant. Significant positive SCA effects were observed in two crosses for pods/plant, four crosses for seeds/ pod and three crosses for 100-seed weight. Although some crosses were showing positive SCA effect for yield and its components, the frequency of unfavorable cases were more. Only TARM-1 × OGG-12 exhibited favorable SCA effect for all characters. Considering all the characters simultaneously, OGG-12 was the best combiner followed by TARM-1 and LGG-460

Genetic Components and Correlation Coefficient for Earliness and Grain Yield in Rice

The present research was conducted to study earliness and their correlations with grain yield in rice breeding. It was carried out during 2012 and 2013 growing seasons at RRTC Farm, Sakha, Kafr El-Sheikh, Egypt. F1 were evaluated along with their parents for genotypic variation. ANOVA revealed significant differences at the 0.01 level among crosses and parents as well as between parents and crosses. These results indicated a wide range of variations among parental groups. The mean squares of parents vs. crosses were found to be significant for all grain yield and its component characters. Variance among crosses indicated significant SCA effects at the 0.01 level for all its component traits. Concerning GCA effects four entries; Sakha 101, Novator, Anait and Large Stigma exhibited positive significant estimates at 0.01 levels for grain yield /plant. The desirable hybrid combinations Giza 179 X Large Stigma and Sakha 105 X VNIRB 572 exhibited significant values of SCA effects at 0.01 and 0.05 levels for grain yield. Heritability estimates in narrow sense ranged from low to moderate. Sakha 101 X Novator, Sakha 106 X Novator and Giza 179 X Large Stigma were the promising hybrid combinations for improving yield character according to results for mid and better parent heterosis. Positive significant correlation coefficient at 0.01 level was recorded between 1000-grain weight and grain yield/plant. The four earliness component traits understudy contributed directly to the earliness character. Also, the earliness component traits; days to heading, days to maturity and elongation of panicle initiation had a direct contribution to yield component.

Combining ability analysis and gene action studies in pearl millet [Pennisetum glaucum (L.) R Br.

The experiment was conducted with 50 hybrids which were developed through Line x Tester mating design using five male sterile lines and ten restorers as parental material along with two standard check hybrids, viz., Pratibha-1666 and Shradha. . The parents, hybrids and two standard checks were evaluated during kharif 2012 season for ten characters. Significant differences were observed for all the ten characters studied. Among females, 732A was found best general combiner for grain yield and had significant GCA effects for days to 50% flowering, days to maturity, 1000-grain weight and plant height while, in male parent, PT 4801 was the best general combiner followed by PT 4108 and PT4563 for grain yield per plant. The cross ICMA 88004 x PT 4639 was the best specific combiner for grain yield per plant followed by ICMA 91222 x PT 4520 and ICMA 99222 x PT 4801. They produced significant and desirable SCA effects for most of the traits studied, indicating potential for exploiting hybrid vigour in breeding programme.

Heterosis and combining ability studies for yield and its component traits in Maize (Zea mays L.)

Heterosis and combining ability was studied in F1 hybrids of maize with respect to grain yield and yield attributing traits using twenty-two hybrids which were developed through Line × Tester mating design. The parents and their hybrids were subjected to assess the combining ability and nature of gene action governing the quantitative traits. The results inferred that the predominance of non-additive gene action was observed for all the traits. Among the parents, the overall study of gca effects suggested that parent UMI 1200-7-26-1-6-1, N 14, N 107 and N 285 were significant general combiner for yield, these can be used to improve hybrids with desirable traits in future. Significant positive SCA effects were found for all the studied traits. Among the hybrids, N 14 × UMI 1200-7-26-1-6-1 showed desirable standard heterosis percentage over the checks CO 6 and NK 6240 along with good sca effects and per se performance for grain yield and other important yield contributing traits over different locations thus it can be used for commercial seed production programme.