Heterosis For Days Research Articles

Heterotic Studies for Yield and Yield Attributing Characters in Finger Millet (Eleusine coracana L. Gaertn)

In the present investigation twelve crosses were generated by crossing three lines with four testers in Line × Tester mating design during kharif 2023 at Agricultural Research Station, Perumallapalle, Tirupati. Twelve crosses along with seven parents and check (Tirumala) were evaluated during rabi 2023-24 in Randomised Block Design with two replications at Agricultural Research Station, Perumallapalle, Tirupati. ANOVA revealed significant difference among genotypes for all characters studied. Heterosis studies helps in finding out superior hybrids over mid parent (Average heterosis), better parent (heterobeltiosis) and standard check (economic heterosis). Among the crosses, PPR1216 × VL 400 was identified as superior cross as it recorded high magnitude of per se performance and all three types of heterosis for days to 50% flowering, number of productive tillers per plant, number of fingers per ear and grain yield per plant. The heterosis will be exploited through selection of superior and character specific genotypes in the segregating generations for the evolution of high yielding varieties. Statistical analysis was carried out by using OP STAT and R Software.

Estimation of heterosis for yield and yield contributing traits in bottle gourd [Lagenaria siceraria (Mol.) Standl.

Twenty eight F1 hybrids developed from a diallel set involving eight parents (excluding reciprocals) in bottle gourd were evaluated at Horticulture complex, Department of Horticulture JNKVV. Jabalpur (MP). The study was aimed to estimate heterosis for yield and yield contributing traits in bottle gourd. Analysis of variance revealed the presence of considerable variability among parents and hybrids for all the characters under study. Heterosis for fruit yield per vine ranged from -1.27 to 17.33 % over mid parent and 0.61 to -22.74% over better parent. For number of fruits per plant and average fruit weight was ranged from 0.25 to -25.30% and 1.37 to 46.67% over mid parent and -0.17 to -33.44% and 0.00 to 41.94% over better parent, respectively. Regarding fruit length the heterosis ranged from 0.64 to 16.50 over mid parent while heterosis over better parent ranged from -0.51 to -22.85. Heterosis for days to first fruit harvest ranged from 0.00 to -12.02 and 0.00 to -14.51 over mid parent and better parent, respectively. It was important to note that only two F1 hybrids viz. Arka Bahar x Kashi Ganga and Arka Bahar x Pusa Naveen exhibited higher positive and significant values over better parent. While, crosses Arka Bahar x Narendra Dharidar, Kashi Ganga x Narendra Dharidar, Pusa Santushti x PSPL and Arka Bahar x Samrat showed significant negative heterosis over better parent for earliness.

Hybrid Vigour and Combining Ability in Biofortified Maize (Zea mays L.)

The study was conducted during winter season of 2020–2021 and rainy season of 2021 at Maize Research Station, Sardarkrushinagar Dantiwada Agricultural University, Bhiloda, Gujarat, India. The aim of the study was to assess magnitude of heterosis and combining ability of forty-five single cross hybrids developed by half-diallel mating design involving ten parents and two standard checks. The field experiment was laid out in randomized block design with three replications. The heterosis, combining ability and components of genetic variance were studied for diverse thirteen characters. The analysis of variance revealed that mean square values of genotypes were significant for all the characters which indicated the existence of considerable amount of genetic variation in genotypes for all the characters. Among single crosses, IMR-76×IMR-58 exhibited maximum mean and desired SCA effect and standard heterosis for β-carotene and IMR-53×IMR-72 for kernel yield. The general and specific combining ability variances observed highly significant for all traits except days to tasseling (only additive gene action), anthesis-silking interval and shelling percentage (only non-additive gene action). The σ2A/σ2D ratio indicated that preponderance of non-additive gene action for the inheritance of these characters suggesting due weightage should be given to heterosis breeding for genetic improvement of these traits. The crosses namely IMR-52×IMR-72 and IMR-51×IMR-58 presented significant heterosis for days to maturity, grain yield, iron and β-carotene content.

Analysis of Heterotic Potential for Yield and Its Contributing Traits in Wheat (Triticum aestivum L.)

Fifty-six genotypes were evaluated comprising 45 hybrids, 10 parents and 1 standard check (HD2968) were evaluated in a randomized block design (RBD) with three replications for 12 traits viz. Days to 50 % flowering, days to maturity, plant height, number of tillers per plant, spikelets per spike, ear length, spike density, number of ears per plant, number of grains per ear, seed index, grain yield per plant and harvest index to study the magnitude and direction of heterosis for yield and earliness in wheat. Significant heterosis was found over mid parent and commercial checks for all the traits studied in desirable direction. The findings revealed highly significant differences between parents and F1’s as well as among parents for the majority of attributes. In the present research investigation, the number of days taken for 50 % flowering and days to maturity was selected as indicative of earliness. Among 45 crosses, K1317 x HD2967 expressed negative significant heterosis over mid parent and standard check respectively, for days to 50% flowering while Cross HD3059 x DBW3059 revealed highly significant negative heterosis for days to maturity. In present research, the highest positive and significant heterosis over mid parent was exhibited by cross DBW187 x HI153 followed by DBW187 x DBW3059, HD3294 x DBW3059. The cross DBW187 x DBW3059 followed by DBW187 x HD3059, HD3294 x K1601 shows highly positive heterotic percent for grain yield per plant over standard check. These hybrids may further be tested over various locations before release for commercial cultivation. High estimates of heterosis obtained in hybrid combinations revealed considerable genetic divergence among the parental lines and reveals good scope for commercial exploitation of heterosis in wheat.

Analysis of Heterosis and Heterobeltiosis for Earliness, Yield and Its Contributing Traits in Okra (Abelmoschus esculentus L. Moench)

Thirty-six F1 hybrids were generated from nine lines and four testers through line x tester mating design, these F1’s along with 13 parents and 1 commercial check (Punjab-8) were evaluated to study the magnitude and direction of heterosis for growth and earliness over various characters in okra. Heterosis was studied to compare traits such as days to 50% flowering, days to picking, plant height, number of internodes, number of branches per plant, fruit length at commercial maturity and final maturity, number of fruits per plant, number of seeds per fruit, 100 seed weight, fruit weight, and yield per plant. Significant heterosis was found over better parent (Heterobeltiosis), mid parent and commercial checks for all the traits studied in desirable direction. The present study showed that the crosses L3 x T2 (19.04, 15.41, 8.28), L5 x T2 (41.90, 14.55, 7.47), L8 x T3 (23.75, 6.48, 8.46) recorded significant positive heterosis for yield per plant over mid parent, better parent and over standard check. Same hybrid L3 x T2 exhibited negative and highly significant heterosis for days to 50% flowering and days to first picking (-11.65,-12.00, -8.33) and (-11.79, -12.12, -15.94) respectively that are earliness character over mid parent, better parent and standard check. These hybrids may further be tested over various locations before release for commercial cultivation. High estimates of heterosis obtained in hybrid combinations revealed considerable genetic divergence among the parental lines and reveals good scope for commercial exploitation of heterosis in okra.

Heterosis for grain yield and quality characters in pearl millet (Pennisetum glaucum (L.) Br.)

In present study Line x tester analysis was carried out to estimate all three types of heterosis (heterobeltiosis, averageand standard heterosis) for identification of superior cross combinations of pearl millet [Pennisetum glaucum (L.) R. Br.].Crosses attempted between 10 testers and four male sterile lines during summer, 2019. Forty hybrids along with four male sterile lines, 10 testers and check MPMH 17 were grown at Research farm of AICRP on pearl millet, Mandor (Jodhpur) Rajasthan during kharif, 2019 and evaluated for thirteen characters. Analysis of variance revealed that sufficient genetic variability present among parents and hybrids for all the studied characters. The results indicated presence of significantly high heterosis in desirable direction for all the characters except grain yield per plant and harvest index (standard heterosis) and protein and iron content (heterobeltiosis). The hybrids, ICMA 94111 × RIB 37-40 S/17 and ICMA 96666 × RIB 16300 showed positive standard heterosis for grain yield per plant with desirable negative standard heterosis for days to 50 % flowering. The hybrid, ICMA 97111 × RIB 17 S/109 showed significant positive standard heterosis for plant height, panicle diameter, test weight and stover yield per plant over check MPMH 17.Hybrids, ICMA 96666 x RIB 16300 and ICMA 94111 x RIB 37-40 S/17 also had higher level of iron content and hybrid ICMA 96666 x RIB 16300 additionally had higher protein content.

Studies on the Expression of Heterosis in Interspecific Hybrids of Sesame (Sesamum indicum L.)

The present study was undertaken to develop superior hybrids for yield and its component traits in Sesamum indicum L. through interspecific hybridization by utilizing S. malabaricum as one of the parents. Direct and reciprocal crosses were attempted using eight cultivated varieties and S. malabaricum, which evaluated a total of fifteen interspecific hybrids. Highly significant and positive heterosis was observed in a few hybrids for the vegetative traits. For single plant yield, the number of seeds per capsule, 100 seed weight, highly significant and negative heterosis was observed. The hybrid SVPR 1 x S. malabaricum had expressed significantly negative relative heterosis for days to first flowering, days to maturity, and plant height. The cross S. malabaricum x TMV 3 had shown highly significant and positive relative heterosis for the number of primary and secondary branches the number of capsules on the main stem and branches.

Genetic improvement of peanut (Arachis hypogea L.) genotypes by developing short duration hybrids

Peanut, the only cash crop of rainfed areas of Pakistan, is facing immense challenges due to global warming. Climatic factors particularly the temperature fluctuations and rain pattern shift significantly impact the production and yield of peanut and unavailability of resilient varieties exacerbate this impact. To deal with the cropping pattern change and yield losses, due to climate vagaries, a study was conducted to develop early maturing hybrids using line into tester mating design. The F1 hybrids from the parental lines were produced in the year 2018 using Line × Tester mating design and then grown in the field in the year 2019 for further evaluation. The hybrids were evaluated based on the early maturity and yield-related attributes in comparison with the parental lines. Based on the general combining ability estimate, line V-3 (Golden), was found as best parent with highly significant values for plant height, days to peg formation, days to maturity, number of pegs per plant, number of pods per plants, number of seeds per plant, 100 pod weight 100 seed weight. Similarly, tester V-7 (PI 635006 01 SD) showed highly significant results of GCA for days to germination, day to 50% flowering, plant height, days to peg formation, days to maturity, number of pegs per plant, number of pods per plants, number of seeds per plant, 100 kernel weight, shelling percentage. All the combinations were evaluated for specific combining ability and significant results were observed for V-3 × V-4 (Golden × PI 619175 01 SD) and V-1 × V-6 (BARI-2000 × PI 564846 01 SD) by developing or maturity and yield-related attributes. The hybrid combinations V-3 × V-5 (Golden × PI 635006 01 SD) followed by V-3 × V-6 showed highly significant results for mid parent heterosis and better parent heterosis for days to 50% flowering, plant height, days to peg formation, number of pegs, days to maturity, number of mature seeds per plant, shelling ratio, 100 pod weight and 100 kernel weight. These parents and hybrid combinations with early maturity genes and high yield attributes can further be used for the development of short duration variety.

Heterosis study for yield and yield attributes in pearl millet [Pennisetum glaucum (L.) R. Br.

The present study was undertaken to assess the magnitude of heterosis of 28 hybrids derived from eight parents of pearl millet through diallel mating design excluding reciprocals. Hybrids exhibited from low to high significant mid parent heterosis, heterobeltiosis, and standard heterosis in desired direction for all the traits except standard heterosis for days to flowering as well as number of effective tillers per plant. The hybrid 17548 × 15388 manifested significant economic heterosis in desirable direction for grain yield per plant with plant height, test weight and protein content. The cross 15851 × 15725 also showed high heterotic magnitude over check for grain yield per plant with traits like days to flowering, days to maturity, harvest index and test weight. The heterobeltiosis for grain yield per plant ranged from -58.60 to 350.02 per cent, while the standard heterosis for grain yield per plant ranged from -61.30 to 48.72 per cent. The highest heterobeltiosis was recorded by the hybrids viz.15058 × 15725 and 15058 ×15388.

Gene Action Studies in Cowpea Inbreds and Hybrids with Varying Levels of Heterosis

Background: Cowpea is an important pulse crop grown worldwide that fits well in a variety of cropping systems. Improvement in yield and related characters along with reduced duration are desirable traits in this crop. The study of heterosis reveals the type of gene action involved which enables the plant breeder to adopt suitable breeding methodology for its improvement. Methods: The present investigation was carried out with 10 parent partial diallel design to analyse the gene action and estimate of heterosis with respect to nine yield related traits in cowpea.Result: Highly significant variances observed for all the traits indicated that hybrids and parents were different from each other for the traits under study and that variability in the breeding materials was attributed to additive and non-additive gene effects. Perusal of the data revealed significant positive heterosis for all yield related traits and significant negative heterosis for days to 50% flowering indicating earliness. Among the twenty five crosses studied, VS9 x VS43, VS24 x VS45 and VS44 x VS47 had significant heterosis for maximum number of characters. Both gca and sca variances were significant for all the characters indicating both additive and non-additive gene actions controlling the various traits. The additive variance was much higher than dominance variance for the characters days to 50% flowering, pod length, pod breadth, pod weight, pods per plant and cluster, pod yield per plant, seeds per plant and length of harvest period suggesting the preponderance of additive gene action.

Combining Ability and Heterosis for Some Yield Component Traits in a 10x10 Diallel Cross of Rice (Oryza sativa L.)

A ten – parent diallel experiment was carried out at the Teaching and Research Farms of the Federal University of Agriculture, Makurdi, Nigeria, to estimate combining ability and heterosis in rice. The design was a 10x10 alpha lattice with three replications and data was collected on plant height (PH), tiller numbers/plant (TN), leaf length (LL) and width (LW), days to flowering (DF), panicle length (PL), panicle exsertion (PE), spikelet numbers/panicle (SN), 100 seed weight (100SW) and days to maturity(DM). A preponderance of both additive and non – additive gene action with both negative and positive GCA, SCA and % heterosis was observed in the control of yield component traits in the studied rice varieties and their hybrids. Non – additive variance was higher, except for DF, SN and DM where additive variance was higher compared to non – additivity. Six parents, namely MGD 101, FARO 44, FARO 52, FARO 57, STRASSA 58 and IR 72 recorded the highest GCA values for most of the traits and the least values in terms of days to flowering and maturity. These parents were the most frequent in crosses with the highest SCA effects and % heterosis for Tiller number, Leaf length, leaf width, panicle length and Spikelet numbers/panicle. Crosses involving these six parents also recorded the least SCA effects and % heterosis for days to flowering and maturity. Based on the results of GCA, SCA and % heterosis, backcross breeding of F1s to their respective parents (the six parents), was recommended for improvement of yield component traits.

Development of heterotic hybrid in bitter gourd (Momordica charantia L.) for earliness and high fruit yield

The present investigation was undertaken to study the magnitude of heterosis in 45 hybrids (F1s) developed by following the Line × Tester mating design using fifteen lines and three testers for earliness and high fruit yield. Among the parents, OBGCBR-2 and IC-085611 have performed as superior genotypes for heterosis. Highest degree of heterosis for most of the traits i.e., earliness and fruit yield traits were registered in desired direction in the hybrid OBGCBR-2 × Jaunpuri Green. Estimation of standard heterosis in cross OBGCBR-1 × IC-085611 recorded desired relative heterosis for days to 50% pistillate flowering. Heterosis for node at which 1st pistillate flower appears was in the desired direction in cross OBGCBR-2 × Jaunpuri Green for standard check and; hybrid Meghna × Jaunpuri Green for relative heterosis and heterobeltiosis. Hybrids Katehi × IC-085612 exhibited negative and significant relative heterosis and heterobeltiosis for internodal length. In case of sex ratio and fruit length cross OBGCV-2 × IC-085612 showed heterosis in desired direction for relative parent and heterobeltiosis. The positive and significant, relative parent and heterobeltiosis was in the hybrid Green Jhalari × Jaunpuri Green for fruit diameter. For average fruit weight positive and significant heterosis observed in cross OBGCBR-2 × IC-085611 over standard parent. Estimation of standard heterosis for number of fruit plant-1 indicated that the hybrids OBGCBR-2 × IC-085611 found to be desirable superior cross combinations over standard heterosis followed by Meghna × Jaunpuri Green for relative parent and heterobeltiosis.

MOLECULAR DIVERSITY OF nrDNA ITS REGION AFFECTED HETEROSIS IN SUNFLOWER (Helianthus annuus)

A study was conducted to specify mutations of the internal transcribed spacer (ITS) in the nucleotides of nuclear ribosomal DNA (nrDNA) and their molecular relationship with heterosis exhibited by the six A- lines and three R-testers of sunflower. The trail was conducted at the fields of the College of Agriculture, University of Anbar, Abu Ghraib during two seasons (spring and fall 2016). Parental lines were crossed according to lineΧtester crossing scheme to produce 18 single hybrids, genotypes were sown to assess their phenotypic performance in the fall season. Results of the molecular analysis of ITS sequencing showed that the rearrangement of single nucleotides had accumulated in a higher rate in the F1 hybrids compared with their ancestor inbreds. The total number of mutations was 268, and deletion mutations accounted for the largest proportion with 209 mutation (71 in lines and 138 in hybrids). In contrast, the transition mutations were 25 all occurred in the hybrids, however the number of transversions recorded 17only. Based on DNA sequence of the nrDNA ITS region the total genotypes were separated into two main groups in cluster analysis following the nearest neighbor method. There was a significant convergence between R2 and both A4ΧR2 and A6ΧR3 hybrids scoring higher values of similarity in context ITS sequence. To be specific, the hybrid A2ΧR3 exhibited the best desirable heterosis for days to 75% flowering and leaf area, while hybrid A5ΧR3 had the highest heterosis for head traits, height and area.

Estimation of heterosis for yield and yield attributing traits in tomato crossed with line and tester method

This study was conducted to estimate heterosis for the yield and yield contributing traits of 32 cross combinations involving 12 diverse lines of some Bangladeshi tomato genotypes considering line x tester mating fashion at the experimental field of Sher-e-Bangla Agricultural University, Dhaka in 2016-2017 and 2017-2018 winter season. The experiment was designed in a Randomized Complete Block Design (RCBD) with three replications. The analysis of variance (ANOVA) showed highly significant difference for all the characters suggesting the presence of genetic variability among the studied materials. Four cross combinations (L1xT1, L3xT2, L3xT3, L5xT1) showed desirable negative significant heterosis for days to first flowering in both relative heterosis (RH) and heterobeltiosis (HB) ranged from -2.56% to -19.05%, respectively. Highest positive significant heterosis in both RH and HB was observed in four crosses L4xT4 (63.48% and 48.25%), L5xT2 (46.77% and 46.27%), L5xT4 (62.58% and 34.78%) and L8xT3 (37.39% and 35.12%) for individual fruit weight (g), while six crosses L1xT2, L1xT4, L3xT2, L4xT4, L5xT4 and L6xT1 exhibited highest positive significant heterosis for yield per plant (kg) in both HB and RH ranged from 16.09% to 88.46% respectively. Heterotic hybrids with maximum number of studied desirable yield contributing traits (8) of both RH and HB were identified only two crosses L1xT2 and L4xT4.
 Progressive Agriculture 30 (2): 179-185, 2019

Heterosis in ridge gourd (Luffa acutangula L. Roxb.) for fruit yield and quality traits

The present investigation was conducted to investigate the extent of heterosis in 33 F1 hybrids of ridge gourd for growth, yield and quality traits in four environments comprising of two seasons and two locations during 2017. These 33 hybrids were obtained by crossing 11 genetically diverse inbred lines with 3 testers in line x tester mating fashion. For fruit yield per vine, significant economic heterosis in positive direction against the best check “Kaveri” was reported in three crosses viz., L11 × T3 (41.64%), L8 × T3 (31.59%) and L11 × T2 (11.26%). The significant estimates of heterosis for fruit yield in positive direction were recorded in 12 hybrids over mid parent with range varied from 10.07% to 68.33% and in 5 hybrids over the better parent with range varied from 15.60% to 67.45%. The hybrid L8 × T3 exhibited maximum negative heterobeltiosis and standard heterosis for days to first harvest followed by hybrid L11 × T2 and L11 × T3. These best performing crosses can be utilized in heterosis breeding programme for improvement of ridge gourd.

Unveiling superior cross combination in maize (Zea mays L.)

An experiment was conducted to find out the heterotic and heterobeliotic in maize during 2013-14 at Agricultural Research Institute, Dera Ismail Khan to get the superior cross combination expressing high hybrid vigour. The crosses were made in 2013 and F1 hybrids along with their parents were studied in 2014. Six maize inbred lines viz; Islamabad-white, Buffa Selection I, Sahiwal-2002, Sadaf, Islamabad Gold and Azam were used and full diallel approach was adopted to get the superior cross combination and to unveil best cross combination. Data were recorded on days to 50% pollen shed, days to 50% silking, plant height, number of ears plant-1 , ear length, number of kernel rows ear-1 , number of kernel row-1, 1000 kernel weight and grain yield kg ha-1. The analysis of variance revealed that means squares due to progenies and their parents were highly significant for all the traits except number of kernels ear-1 and 1000 kernel weight which showed significant differences. Only number of kernels row ear-1 depicted non-significant variation. The analysis of variance (Table 1) showed that mean squares due progenies and parents were highly significant for all the traits. Twenty two crosses had positive heterosis ranged from +0.84% (BS-1 x Sadaf) to 51.3 % (Islamabad-white x Sadaf) for grain yield kg ha-1. For days to 50% pollen shed, heterosis ranged from (-10.8 to +0.6%). The twenty seven hybrids showed negative heterosis, while the two hybrids showed positive heterosis for days to 50% silking. For plant height twenty seven crosses showed positive heterosis ranged from (0.0% to 15.5%). The heterosis and heterobeltiosis for number of ears palnt-1 ranged from (-11.5% to 16.0 %), (-14.6 to +13.8 %) respectively. For ear length heterosis ranged from +0.12% (Islamabad-white x BS-1) to +26 % (BS-1 x Islamabad gold). Heterosis and heterobeltiosis ranged from +2.5 % (BS-1 x Islamabad-white) to 9.1 % (Sahiwal-2002 x Islamabad white) and 4.7 % (BS-1 x Azam) to 7.6 % (Sahiwal-2002 x Islamabad-white) for number of kernel rows ear-1. 1000 kernel weight showed heterosis and heterobeltiosis ranged from +1.5 (BS-1 x Azam) to +19.5 % (Islamabad white x Sadaf) and +0.2 % (Azam x Islamabad white) to 19.2 % (Islamabad white x Sadaf). Hence it is suggested that 3 parents viz; Islamabad Gold, Sahiwal 2002 and Sadaf can give promising yield if included in breeding experiments to unzip genetic configuration. Keyword: Maize; Inbred lines; Heterosis and heterobeltiosis http://dx.doi.org/10.19045/bspab.2017.60071

Heterosis and combining ability analysis in snowball cauliflower using indigenously developed CMS lines

Five CMS lines, Ogu12A, Ogu13A, Ogu14A, Ogu15A and Ogu16A were selected among fifteen lines after BC7 based on superior commercial, floral and seed setting traits. Line × Tester analysis was done by taking these five CMS lines as female parent with ten diverse lines of snowball cauliflower as testers. Data were recorded for 14 important vegetative and commercial traits. For days to 50% curd initiation and days to 50% curd maturity the CMS line Ogu15A exhibited significantly high GCA effect in negative direction (−14.52 and-14.38). For marketable curd weight and marketable curd yield significantly high GCA effects were recorded in the CMS line Ogu15A (0.11; 0.10) and Ogu13A (5.28; 4.75). Among the ten testers only two genotypes, Kt-2 and EC-162587 had significantly high GCA effect for marketable curd yield. Very high and significant SCA effect has been recorded in the combination Ogu16A × Kt-25 (20.25) and Ogu15A × Kt-2 (19.72) for marketable curd yield. The CMS line, Ogu15A was involved in the most of the heterotic combinations for earliness. Average heterosis was in desirable positive direction for 7 among 14 traits. The range of average heterosis for days to 50% curd maturity was-8.55 to 25.0% and it was-32.04 to 127.91% marketable curd yield. Ogu15A was involved in maximum number of combinations for earliness and higher productivity. Highest heterosis for marketable curd yield was recorded in the combination, Ogu15A × Kt-2 (127.91%), followed by Ogu14A × Sel-26 (90.90%) and Ogu15A × Sel-26 (86.18%). The CMS lines with better combiling ability are involved with most of the heterotic combinations for different traits thus can be used for development of F1 hybrids.

Heterosis in bottle gourd Lagenaria siceraria (Mol.) Standl.

Studies were carried out to estimate heterosis for yield and yield traits in bottle gourd. Heterosis for fruit yield per vine ranged from -35.2 to 23.9 per cent over mid parent and -17.6 to 68.5 per cent over standard check Samrat. For number of fruits per plant and average fruit weight was ranged from -28.2 to17.9 per cent and -22.1 to 22.4 per cent over mid parent and -17.6 to 53.3 per cent and -11.7 to 44.6 per cent over standard check Samrat, respectively. Regarding fruit length the heterosis ranged from -15.1 to 19.9 over mid parent while standard heterosis ranged from -7.05 to 48.9. Heterosis for days to first fruit harvest ranged from -0.53 to -12.4 and -0.55 to -14.7 over mid parent and standard check respectively. It was important to note that six F1 hybrids viz., Samrat X Aditi followed by Aditi X TC 092372, IC 093236 X TC 092372, Samrat X TC 092372, Samrat X IC 093236 and Aditi X PSPL produced significantly higher yield than the standard check Samrat.

Heterosis and combining ability for grain yield and yield component traits of maize in Eastern Ethiopia

Combining ability analysis for grain yield and yield component traits in maize were carried out in 8×8 diallel cross. The analysis of variance showed there is highly significant variation between the genotypes for all the traits considered. Year of testing was significant only for days to maturity and grain yield per hectare. The highest percentage of heterosis for grain over the standard varieties (BH 660) was observed by the cross L1 x L4 (29.3%) followed by crosses L1 x L5 (28.3%), L3 x L5 (21.7%) and L1 x L7 (20.8%). Mid-parent heterosis for days to maturity ranged from -2.5 to -23.9%, whereas that of better parent heterosis ranged from 0 to -13% indicating that the hybrids tend to be earlier in maturity than the parents. The mean squares due to GCA for days to maturity, ear diameter, member of kernels per row, 1000 kernel weight and grain yield were significant, indicating the importance of additive genetic variance in controlling these traits. The mean squares due to SCA were also significant for days to maturity, ear length, member of kernels per row and 1000 kernel weight indicating the importance of non-additive genetic variance in controlling these traits. The inbred lines L1, L3, and L4 were good general combiners for grain yield.Keywords: Maize, Combining ability, General combining ability, Specific combining ability, Standard heterosis

Studies of standard heterosis for quantitative traitsin eggplant (Solanum melongena L.)

Standard heterosis has been amply exploited in developing hybrids in eggplant by increasing commercial value of them. In an experiment, fifteen parents (12 lines and 3 testers) were selected on the basis of divergence and mated them in line x tester design. Hybrids and parents rose to measured heterosis for different quantitative traits. Some of the hybrids exhibited positive standard heterosis. In case of days to 50 per cent flowering, plant height and days to maturity, where negative heterosis is desirable, seven hybrids showed negative standard heterosis for days to 50 per cent flowering, twenty four hybrids for plant height and three hybrids showed significant negative heterosis for days to maturity. For number of branches per plant, three hybrids showed significant and twenty hybrids showed positive standard heterosis. In case of fruit length and fruit diameter both positive and negative heterosis was observed. Twenty six hybrids showed positive standard heterosis for number of fruits per plant. Yield, the ultimate product of different yield components, nine hybrids showed positive standard heterosis for yield. In case of Cercospora leaf spot incidence, seventeen hybrids showed highly significant standard heterosis.