Significant Positive Heterosis Research Articles

Estimation of Heterosis for Plant Growth, Oil Content and Yield Related Traits in Indian Mustard [Brassica juncea (L.) Czern and Coss] Using Half Diallel

Genetic investigation was carried out diallel design for heterosis analysis studies the experimental material comprised with eight parents with two checks was carried out to identify high heterotic crosses and their relationship in Indian mustard. Several hybrids exhibited heterobeltiosis and standard heterosis for seed yield per plant and other characters. The heterosis analysis revealed substantial hybrid vigor across 28 hybrid crosses, with noteworthy improvements in traits such as earlier flowering, earlier maturity, and increased seed weight. The seed yield per plant exhibited better parent heterosis ranging from -20.71% to 16.28%, with five crosses yielding more seeds than their better parents. P3 (PM-22) X P8 (RH-749) was the best cross, with a 16.28% increase. Standard heterosis ranged from -38.72% to 35.14%, with ten crosses showing significant positive heterosis. The findings from this investigation provide crucial insights into the genetic performance and breeding potential of Indian mustard genotypes. The identified parental lines and cross combinations with desirable heterosis effects offer valuable resources for breeding programs aimed at developing high-yielding and resilient mustard varieties, contributing to the advancement of agricultural practices and crop improvement. The above best parent and best crosses can be used in hybridization and heterosis breeding respectively.

Assessment of Heterosis in Inter-varietal Hybrids of Mangalore Melon (Cucumismelo var. acidulus) for Yield and Quality Traits

Mangalore melon is one of the distinct class of Cucurbitaceae family widely grown in southern part of India. Despite of having many nutritional values, there is scope for systematic hybridization study to improve the many qualitative and quantitative traits. An investigation was undertaken to develop inter-varietal hybrids and their evaluation to assess the extent of heterosis in newly developed hybrids between selected genotypes of Mangalore melon during kharif, 2019 and 2020 at College of Horticulture, Sirsi, Karnataka, India. A total of 16 intervarietal hybrids were developed by crossing 15 parental lines. Hybrids were developed using hand emasculation and hand pollination technique and the developed hybrids were evaluated using RCBD design with two replications. The results showed significant positive heterosis over mid parent and better parent for all the hybrids. The hybrids Soubhagya×RNMS-1 exhibited highest and significant heterosis over both mid parent (88.05%) and better parent (72.69%) followed by MS-19×MS-5 over mid parent (73.09%) and better parent (61.10%). From this study, it was concluded that hybrid Soubhagya X RNMS-1 was superior over their parents for most of the traits with the total yield of 8.44 kg plant-1. These best performing hybrids are need to be studied for their stability and commercial exploitation, resistance of pest and diseases, keeping quality of hybrids (storability) and experimentation on hybrid seed production technologies as well as storability of seeds should be done.

Studies on Heterozsis Breeding in Brinjal Germplasm for Growth and Yield Traits, Solanum melongena L.

Brinjal, Solanum melongena L. is one of the commercial annual vegetables grown all over India for its edible fruits. Heterosis in vegetable crops helps to exploit the superior hybrids based on its phenotypic superiority over their parents and indicates predominance of non-additive genetic effects. This research was carried out at Department of Vegetable Science, Horticultural College and Research Institute, Periyakulam. The study involves six parents and thirty hybrids laid out in Randomised Block Design with two replications. The cross CO2 × Kothampatti Kathiri, obtained significant positive heterosis (16.53%) for plant height over better parent. Significant heterosis over mid parent was observed for number of branches in Kothampatti Kathiri × Odavai Pachai Kathiri, 33.33%, fruit width in Dharmapuri Oodha Kathiri × Poiyur Purple Kathiri, 25.54%, fruit length in Kothampatti Kathiri × Gobi Pachai Kathiri, 24.33%. Significant negative heterosis over better parent for number of days to 50% flowering was observed in the cross Odavai Pachai Kathiri × Gobi Pachai Kathiri, -9.25%. Significant positive heterosis over standard check was obtained for number of fruit per plant, 35.42% in the cross Dharmapuri Oodha Kathiri × CO2 and fruit yield per plant in Dharmapuri Oodha Kathiri × Odavai Pachai Kathiri, 21.54%. Heterosis exploited could be utilized in further crop improvement program in the development of a superior hybrid.

Genetic potential and inheritance pattern of agronomic traits in faba bean under free and infested Orobanche soil conditions

BackgroundOrobanche is an obligate parasite on faba bean in the Mediterranean region, causes considerable yield losses. Breeding tolerant faba bean genotypes to Orobanche is pivotal to sustain production and ensuring global food security, particularly considering the challenges posed by population growth. In the present study, seven faba bean lines and four testers were used in a line×tester mating design during 2020–2021 and 2021–2022 growing seasons. The eleven parents and their 28 F1 crosses were evaluated under Orobanche free and naturally infested soils.ResultsThe results demonstrated considerable variations among the evaluated genotypes, wide diversity among the parental materials, and heterotic effects for all studied agronomic traits under Orobanche-free and infested soils. Orbanche infestation displayed a significant adverse impact on all the studied agronomic traits. The genotypes Line1, Line2, Line3, and Line5 displayed superior performance under Orobanche-infested conditions and recorded the highest values of all studied agronomic traits. Additionally, Line1, Line2, Line3, Line5, and Line7 exhibited desirable significant GCA for most evaluated traits under the two infestation conditions. The obtained crosses displayed significant negative or positive heterosis for studied agronomic characters such as plant height, number of branches per plant, number of pods per plant, number of seeds per plant, and seed weight per plant were observed. Furthermore, specific cross combinations such as Line2×Sakha3, Line3×Nubaria5, Line7 × Nubaria5, Line6×Nubaria1, Line5×Sakha3, Line1×Sakha3, and Line1 × Nubaria5 exhibited superior performance in seed yield and contributing traits under Orobanche-infested conditions. Moreover, these specific crosses showed superior efficacy in reducing dry weight of Orobanche spikes. The results obtained from GGE biplot analysis closely aligned with those from the line×tester procedure, affirming the significance of GGE biplot as a valuable statistical tool for assessing genotype combining ability in line× tester data. Both additive and non-additive gene actions were reported to be predominantly involved in the inheritance of the studied agronomic traits in faba bean.ConclusionsThe detected genetic diversity within the evaluated faba bean genotypes and their developed crosses exhibits substantial potential for improving faba bean productivity under Orobanche-infested conditions. The parental genotypes, Line1, Line2, Line3, Line5, and Line7, were identified as effective and promising combiners. Moreover, the developed crosses Line2×Sakha3, Line3×Nubaria5, Line7×Nubaria5, Line6×Nubaria1, Line5×Sakha3, Line1×Sakha3, and Line1×Nubaria5 could be considered valuable candidates for developing high-yielding and tolerant faba bean genotypes to Orobanche.

Interpretation of Mean Values and Extent of Heterosis Bottle Gourd [Lagenaria siceraria (Mol.) Standl.

Aims: To Study the mean values and heterosis for fruit yield with associated traits of bottle gourd.
 Study Design: Randomized block design.
 Place and Duration of Study: The seeds of F1 hybrids were produced during summer 2021 at Potato Research Station, S. D. Agricultural University, Deesa.
 Methodology: The experimental material consisted of twelve parents, their 35 Line × Tester crosses and one standard check (ABGH 1).
 Results: The study was undertaken to reveal mean and per cent heterosis level in bottle gourd [Lagenaria siceraria (Mol.) Standl.]. An examination of mean data of parents with (F1) hybrids for fruit yield and associated traits revealed that DBG 5 amongst females and ABGS 11-17 amongst males, while NDBG 132 × PUNJAB LONG, LOCAL × ABGS 14-25, and LOCAL × ABGS 11-17 amongst hybrids exhibited higher mean value for fruit yield per plant with some of its associated traits. The significant relative heterosis, heterobeltiosis and standard heterosis were perceived in many hybrids for different component traits. The F1 hybrids, NDBG 132 × PUNJAB LONG (75.30, 53.04 & 21.64 %), LOCAL × ABGS 14-25 (34.99, 27.77 and 20.71 %) and LOCAL × ABGS 11-17 (31.82, 23.49 and 19.27 %) manifested significant and positive heterosis over mid parent, better parent and the standard check ABGH 1 for fruit yield per plant. These crosses were also given best mean performance, hence hold promising for commercial exploitation.
 Conclusion: The analysis of variance revealed that significant differences among the parents for all traits. This indicated a sufficient variability in the parents (i.e., lines and testers) for studied trait. The best heterotic crosses NDBG 132 × PUNJAB LONG, LOCAL × ABGS 14-25, LOCAL × ABGS 11-17 and GPBG 108 × ABGS 11-24 for fruit yield per plant revealed significant positive heterosis over mid parent, better parent and standard check.

Heterosis and combining ability estimates for okra (<i>Abelmoschus esculentus</i> L. Moench) varieties for yield attributing characters in Sudan savanna of Nigeria

Two location trials were conducted at the Teaching and Research Farm of the University of Maiduguri and screen house of the Faculty of Agriculture during 2018/2019 dry season to estimate the combining ability variance, general combining ability (GCA) effects of parents and specific combining ability (SCA) effects of crosses with six okra genotypes. They include: three improved varieties NHAe 47-4, LD-88, Clemson spineless and three locals, Chalawa, Syria and Sola, crossed in a 3 x 3 line x tester mating design to generate nine F1 hybrids. All the F1s along with their parents were evaluated in a Randomized Complete Block Design (RCBD) and Completely Randomise Design (CRD), with 3 replications. Positive heterosis were observed for number of fruits per plant in the crosses Chalawa x NHAe47-4, Chalawa x Clemson Spineless, this directly indicated their important contributions toward total fruit yield in okra. The variance of GCA and SCA revealed that both additive and non-additive gene actions were important in the control of most agronomic.The ratio of GCA/ SCA indicates greater preponderance of non-additive gene action for the characters in all the traits except number of leaves per plant and days to 50% flowering which were controlled by additive gene actions. The parent Syria was the overall best general combiner among the lines for all characters in the field and Chalawa was the overall best general combiner for all characters measured among lines in the screen house. LD88 recorded the highest GCA effects for all of the characters among testers in both experiments. Similarly, in the field, the hybrid Sola x NHAe47-4 recorded the maximum SCA effect for all characters except days to 50% flowering; Syria x NHAe47-4 was the best SCA for most characters except plant height and also the cross between Syria x Clemson Spineless was the best SCA for most characters except number of fruits per plant. In the screen house, the cross between Chalawa x NHAe47-4, showed superior SCA for all characters measured. Appreciable level of heterosis was observed for most of the characters studied, the overall maximum positive significant heterosis for total fruit yield (kg/ha) was observed in crosses Syria x LD88 (52.80) and Chalawa x NHAe47-4(123.30) over better parents. The preponderance of non-additive genetic effect and the tremendous level of heterosis observed among the characters in the parents and their crosses studied would be great asset in choosing the okra varieties for intercrossing and development of hybrids varieties for commercial production of okra.

Scarce Evidence of Heterosis for Growth Traits in Peruvian Guinea Pigs.

This study aimed to estimate the heterosis for productive traits in a two-way crossbreeding scheme. Four guinea pig lines were originally selected for the following traits: line P1 for the growth rate, P2 for the partial feed conversion rate, M1 for the growth rate of the litter at 10 days of age, and M2 for the litter size at birth. The comparison included 176 purebreds (P1: 46, P2: 43, M1: 54 and M2: 33) and 150 crosses (P1P2: 42, P2P1: 38, M1M2: 11 and M2M1: 59); body weights at birth, 10 days, weaning and 60 days of age were analyzed. A linear fixed-effect model was used, and heterosis was estimated as the difference between the average performance of the crossbred and pure-line animals. The pure line comparisons showed that P2 was lower than P1 for weight at 10 days and weaning weight, while all other comparisons between the paternal and maternal pure lines were not significant. The results indicated significant positive heterosis effects for both types of crosses, but only for birth weight: 3.7% for paternal crosses and 12.7% for maternal crosses. The heterosis estimates were mostly positive but not significant for all other traits. A reason for the low levels of heterosis could be that the lines are not very genetically differentiated. These results suggest that applying a two-way crossbreeding scheme within paternal and maternal guinea pig lines for meat production is not recommended due to the absence of heterosis for growth traits.

Heterosis and Combining ability analysis in F1 hybrids of bread wheat

Bread wheat (Triticum aestivum L.) is the most auspicious cereal food crop with regard to production, consumption, nutritional value, storage space, quality, adaptability and transportation. The all 15 F1 cross combinations and their parents were planted in a randomized block design (RBD) with three replications. Out of 15 cross combinations, only 10 show significant heterobeltiosis for early maturity over the standard check-in desirable direction. Five cross combinations PBW 343 x PBW 65, RAJ 2184 x PBW 65, PBW 343 x RAJ 2184, CPAN 3004 x RAJ 2184, HD 1981 x PBW 154 show significant positive heterobeltiosis whereas two cross combinations HD 1981 x PBW 154 and PBW 343 x PBW 65 show significant positive heterosis over commercial check for seed yield. The GCA (General combining ability) effects of the parent PBW343 showed significant positive effect for most of all the traits followed by CPAN3004, PBW154 and PBW65. Out of fifteen, two cross crosses, namely PBW 343 x PBW 65 and CPAN 3004 x RAJ 2184 showed a significant positive SCA (specific combining ability) effect for grain yield.

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.

Assessment of Inbred Lines of Field Corn for Yield And Yield Attributes Through Line × Tester Method

A line × tester analysis comprising forty eight test-crosses generated by crossing 24 S3 inbred lines derived from commercial maize hybrid 981 with two testers. Heterosis study of these crosses against two standard checks was evaluated at Bangladesh Agricultural Research Institute, Gazipur during rabi 2015-16. The objectives of the study were to estimate general and specific combining ability effects of the inbred lines and to assess the test cross performance and estimate the amount of standard-heterosis of the hybrids for grain yield and yield related characters. Highly significant genotypic differences were observed indicated wide range of variability present among them. Five lines viz. Line 11, Line 14, Line 17, Line 24 and Line 30 were good general combiner for grain yield and possessed high means. Nine crosses showed (Line 18 × BIL22, Line 23 × BIL22, Line 27 × BIL22, Line 7 × BIL28, Line11 × BIL28, Line14 × BIL28, Line 24 × BIL28, Line 25 × BIL28 and Line 30 × BIL28) significant and positive specific combining ability effect for grain yield. The information on the nature of gene action with respective variety and characters might be used depending on the breeding objectives. These crosses, Line 24× BIL28 (11.40 t/ha), Line 18 × BIL22 (11.30 t/ha) and Line 25 × BIL28 (11.20 t/ha) showed higher yield, could be utilized in maize breeding activities. Estimation of heterosis was carried out using two commercial hybrids BARI Hybrid Maize-9 (BHM-9) and NK-40. The percent heterosis for grain yield varied from -23.39 to 4.6% against BHM-9. Among the 48 crosses, 13 crosses exhibited significant positive heterosis for grain yield.
 Bangladesh J. Agril. Res. 46(4): 469-489, December 2021

Heterosis and Combining Ability Analysis in Maize Using Line X Tester Model

Twenty-two lines were crossed with 2 testers in a Line × Tester mating design in 2017-18 and the resulting 44 crosses along with the lines, testers and three checks i.e., BARI Hybrid Maize 9 (BHM 9), 981 and Elite were evaluated in a alpha lattice design with two replications, during rabi, 2018-19. Highly significant differences were found among the genotypes for all the characters studied. Parent and parents vs crosses were significant for all the characters except ASI indicating greater diversity in the parental lines of the traits. Three lines (viz., BMZ 55, BMZ 53, BMZ 4) showed significant negative GCA effect for both days to 50% tasseling and silking, indicating good general combiners for earliness. BMZ 15, BMZ 55, BMZ 53 and BMZ 68 showed significant negative GCA effects for both plant and ear height. BIL 79, Pinacle 17 and BIL 182 exhibited desirable significant positive GCA for grain yield. Considering desirable GCA effects those parents could be used extensively in hybrid breeding program to accumulate those favorable genes. However, two cross combinations BIL 182 x CML 429 and BIL 79 x CML 429 were found promising considering SCA effect, mean performance and could be utilized for enhancing hybrid production. Considering BHM 9 as check, the percent standard heterosis for grain yield varied from -52.6 to 0.6%. None of the crosses showed significant positive heterosis for grain yield except BIL 79 × CML 429.
 Bangladesh J. Agril. Res. 46(3): 261-274, September 2021

Estimation of Combining Ability and Heterosis on Seed Cotton Yield and its Attributing traits in American Cotton Gossypium hirsutum L. Genotypes

An experiment was executed during Kharif 2021 at Regional Agricultural Research Station, Lam, Guntur in randomized block design (RBD) in two replications for estimation of combining ability of the parents and gene effects and also the extent of heterosis using line × tester fashion design. Statistical data were collected on the biometrical observations viz., days to 50% flowering, plant height (cm), number of monopodia/ plant, number of sympodia/plant, number of bolls per plant, boll weight (g), seed index (g), lint index (g), Ginning Out Turn (GOT %), seed cotton yield (kg/ha) and lint yield (kg/ha). The lines GISV298 and SCS1207; the testers, Lam GPC 501 and Lam GPC 355 exhibited positive General Combining Ability (GCA) effects for the traits Ginning Out Turn (GOT%), Seed Cotton Yield (SCY) and Lint Yield (LY) signifying that these were good general combiners. The cross combinations viz., TCH1837/GP117, GISV298/GP274, and SCS1207 / GP117 expressed significant specific combining ability (SCA) effects for Seed Cotton Yield (SCY) and Lint Yield (LY). The cross combination, SCS1207/ Lam GPC 355 was identified as the best hybrid combination with high GCA and SCA for important traits like GOT, seed cotton yield, and lint yield coupled with significant positive heterosis which can be further tested in multi-location testing at the station and all India level.

Heterotic patterns in rapeseed (Brassica napus L.): Crosses between spring-type and winter-type genotypes

Genetic improvement in a crop, viz. Brassica species, through plant breeding essentially requires the presence of adequate genetic diversity within the gene pool. Winter rapeseed is known to be genetically different from spring rapeseed and can therefore be used for extending genetic diversity in the progenies produced via crossing methods. Using line?tester analyses of two spring types of testers and six lines of winter-type rapeseed varieties, heterotic patterns of phenological traits, plant height and seed yield were estimated. Significant mean squares between parents and crosses revealed significant heterosis for all the traits. Line?tester mean squares, indicating the non-additive genetic effects, were significant only for plant height and seed yield. High narrow-sense heritability estimates for phenological traits underline the importance of additive genetic effects and thus the efficiency of selection for improving these traits. Based on the significant and positive expression of heterosis effects for phenological traits and plant height in the winter parents, it was concluded that the F1 progenies had earlier and shorter maturity than the winter parents. F1 progenies were also early flowering, early maturing and taller than the spring-type parents. Significant positive heterosis of the crosses for seed yield was observed in 75% and 42% of F1 progenies compared to the spring and winter parents, respectively, indicating a higher yield potential of the F1 hybrids than the spring and winter parents.

ESTIMATION OF COMBINING ABILITY AND HETEROSIS IN WHEAT

The study used a half-diallel mating fashion to identify combining ability (GCA and SCA) and heterosis of six wheat (Triticum aestivum L.) genotypes and their 15 F1 hybrids for morpho-physiological, yield, and yield-contributing traits. The present study was carried out in a randomized complete block design with three replications. The studied characters are heading days, maturity days, chlorophyll content, Plant height, Effective tillers plant-1, Total tillers plant-1, Spikes plant-1, Spike length, Filled spikelets spike-1, Unfilled spikelets spike-1, Grains spike-1, Thousand grain weight, Grain yield plant-1, Biological yield plant-1, and Harvest index Highly significant differences were observed among genotypes (parents and F1 hybrids) for all characters studied. The results also showed that the mean squares due to general (GCA) and specific (SCA) combining abilities were highly significant for all studied characters except harvest index, indicating the magnitude of both additive and non-additive gene effects in governing these traits. GCA/SCA ratios were greater than one for all characters except filled spikelets spike-1 and harvests index, indicating the dominance of additive gene effects, which play important roles in the inheritance of these characters. While the non-additive effect of the gene predominated in the inheritance of filled spikelets (spike-1) and harvests index, The parent BARI GOM-30 emerged as the best general combiner for total tillers plant-1, filled spikelets spike-1, grains spike-1, thousand-grain weight, grain yield plant-1, and harvest index. Bari Gom-28 was the best general combiner for heading days and maturity days, and Sourav was the best for effective tillers plant-1, spikes plant-1, and biological yield plant-1. The cross BARI GOM-30 SOURAV was the best specific combiner for effective tillers plant-1, total tillers plant-1, spikes plant-1, and PRODIP SOURAV for filled spikelets spike-1. Bari GOM-33 Sourav emerged as the best specific combiner for grain yield plant-1 and Prodip Ayt-5 for grain spike-1. Concerning heterotic effects in comparison to the midparent, the F1 hybrid BARI GOM-28 BARI GOM-33 showed maximum significant positive heterosis for chlorophyll content and biological yield plant-1 and BARI GOM-33 SOURAV for effective tillers plant-1, spikes plant-1, and grain yield plant-1. These parents and cross combinations could be used for the breeding program of wheat for potential yield.

Allele-specific expression and chromatin accessibility contribute to heterosis in tea plants (Camellia sinensis).

Heterosis is extensively used to improve crop productivity, yet its allelic and chromatin regulation remains unclear. Based on our resolved genomes of the maternal TGY and paternal HD, we analyzed the contribution of allele-specific expression (ASE) and chromatin accessibility of JGY and HGY, the artificial hybrids of oolong tea with the largest cultivated area in China. The ASE genes (ASEGs) of tea hybrids with maternal-biased were mainly related to the energy and terpenoid metabolism pathways, whereas the ASEGs with paternal-biased tend to be enriched in glutathione metabolism, and these parental bias of hybrids may coordinate and lead to the acquisition of heterosis in more biological pathways. ATAC-seq results showed that hybrids have significantly higher accessible chromatin regions (ACRs) compared with their parents, which may confer broader and stronger transcriptional activity of genes in hybrids. The number of ACRs with significantly increased accessibility in hybrids was much greater than decreased, and the associated alleles were also affected by differential ACRs across different parents, suggesting enhanced positive chromatin regulation and potential genetic effects in hybrids. Core ASEGs of terpene and purine alkaloid metabolism pathways with significant positive heterosis have greater chromatin accessibility in hybrids, and were potentially regulated by several members of the MYB, DOF and TRB families. The binding motif of CsMYB85 in the promoter ACR of the rate-limiting enzyme CsDXS was verified by DAP-seq. These results suggest that higher numbers and more accessible ACRs in hybrids contribute to the regulation of ASEGs, thereby affecting the formation of heterotic metabolites.

The Exploitation of Heterosis for Yield and its Components of Tomato Hybrids for Use as Commercial Variety Development

A study was conducted in tomato to estimate the magnitude of heterosis for yield and yield related components at the Olericulture Division of Horticulture Research Centre, BARI during the winter season of 2021-22. Appreciable heterosis was found over better parents for all the traits studied in a desirable direction. Significant negative better parent heterosis was expressed for days to first flowering (4 combinations), days to 50% flowing (6 combinations), days to first harvest (7 combinations), and days to fruit maturity (8 combinations), while significant positive better parent heterosis was noticed in seven and three cross combinations for number of fruits per plant and single fruit weight, respectively. In our study, five cross combinations, viz., F1 203 (25.65%), F1 1501 (14.34%), F1 2101 (14.32%), F1 2301 (15.62%) and F1 2501 (16.22%) showed significantly positive better parent heterosis for higher yield. Six combinations were found to have significant positive heterosis with higher values in F1 1903 (21.95%), F1 2001 (19.62%), F1 2101 (12.84%) for TSS, while the significant negative better parent heterosis for TYLCV infection and leaf sucking pest infestation varied from -100% to 0.00%. Thus, it is evident from the data that, based on better parent heterosis of different yield and yield contributing traits, the cross combinations viz., F1 203, F1 1501, F1 2101, F1 2301 and F1 2501 may be investigated further for developing better hybrid tomato varieties.

Study of Heterosis for Yield and Grain Quality Traits in Barley (Hordeum vulgare L.)

Twenty-nine barley genotypes including fifteen crosses, commercial cultivars and elite (exotic) lines wereevaluated to estimate the magnitude of heterosis. Significant mean square due to genotype were observedfor days to maturity, effective tillers per plant, spike length, no. of grains per spike, grain yield per plant,hectoliter weight (kg/hl), grain bold grain %, husk content (%), protein content (%) and starch content (%).Crosses IBON HI 19-94 x RD 2899 followed by IBON HI 19-110 x RD 2786 and IBON HI 19-82 x RD 2035exhibited desirable positive significant heterosis, heterobeltiosis, economic heterosis for grain yield, tillersper plant, spike length, no. of grains per spike and bold grain (%). Therefore, above crosses may be observedas promising types for tangible advancement for yield potential and bold grain. IBON HI 19-82 x RD 2035revealed significant economic heterosis for hectoliter weight, bold grains, husk content and protein contentalong with grain yield. The study revealed good scope for commercial exploitation of heterosis as well asisolation of transgressive segregants among the progenies of heterotic F1 for improvement of yield andgrain quality.

Heterosis for yield and quality traits in traditional and evolved Basmati

A study was undertaken on 36 F1s obtained from diallel (without reciprocals) mating design to explicate the genetic behavior of traditional and evolved basmati varieties for 14 traits. F1s were divided into traditional x traditional (T x T); evolved x evolved (E x E) and traditional x evolved (T x E) basmati types; amidst which E x E and T x E type of crosses exhibited high positive average heterosis in comparison to T x T type of crosses for yield per plant trait. Assessment of quality traits for average heterosis indicated that, all the three types of crosses were equally effective for KL, KB and LBR. Manifestation of average heterosis for KLAC was better in TxT type as none of the ExE type of crosses showed significant positive heterosis; likewise, among 20 T x E type of crosses only 3 crosses showed significant positive heterosis. Heritability in narrow sense was high for: MPL, 100-GW, NGP, YPP, KL, LBR, and KLAC.

Intraspecific hybridization as a mitigation strategy of low salinity in marine bivalve noble scallop Chlamys nobilis

Noble scallop Chlamys nobilis is one of the most important bivalves in China. C. nobilis aquaculture is mainly carried out in coastal areas that vulnerable to high salinity fluctuations. Hyposaline conditions caused by a large volume of freshwater input from rivers in rainy seasons often leads to mass mortalities of farmed C. nobilis. Interspecific hybridization is a promising approach to improve the growth rate, survival rate and environmental adaptability of bivalves. However, it is not clear whether intraspecific hybridization can be used as a management strategy to mitigate the impact of hyposaline on farmed C. nobilis. Therefore, this study compared the effects of hyposaline on the growth rate, survival rate, total carotenoid content (TCC) and transcriptome data of intraspecific inbred and hybrid C. nobilis. The results of this study revealed that intraspecific hybridization of C. nobilis exhibited significant positive heterosis in growth rate, survival rate and adaptation to hyposaline condition. The stronger adaptation to hyposaline condition is mainly attributed to the induction of genes involved in osmoregulation, cell protection and damaged protein repair. Therefore, intraspecific hybridization is a potential management strategy to mitigate the impact of hyposaline on farmed bivalves (at least for C. nobilis).

Heterosis and character association studies in CMS Hybrids of FCV tobacco (Nicotiana tobaccum L.)

Flue Cured Virginia (FCV) tobacco (Nicotiana tobaccum L.) is a promising commercial crop in semi-arid and rain-fed areas delivering economic benefits to farmers in comparison to all other crops cultivated. In India, Andhra Pradesh and Karnataka are the major states cultivating FCV tobacco. In Karnataka, it is cultivated in Karnataka Light Soils (KLS) covering southern transitional zone during kharif season as a rainfed crop. Currently, Kanchan, FCH-222 and CH-3 are the popular cultivars grown in KLS region. Release of improved high yielding varieties/hybrids is the key for varietal diversification and yield enhancement of tobacco in this region. In this connection, commercial exploitation of F1 hybrids through heterosis breeding can play a significant role in enhancing yield and quality. Further very few reports on studies on standard heterosis in FCV Tobacco are available. Hence, the present study involving eight CMS hybrids was undertaken to estimate standard heterosis for yield and yield related traits, and to ascertain interrelationships among the yield related characters and their influence on cured leaf yield. Eight CMS based hybrids (CMS2×A4, CMS6×A4, CMS7×A4, CMS10×A4, CMS2×CY142, CMS6×CY142, CMS7×CY142, CMS10×CY14) were evaluated at ICARCTRI, Research Station, Hunsur, Karnataka, India along with checks for three years (2018-21). Significant higher heterosis in desirable direction for cured leaf yield and for various yield attributing characters was observed among the hybrids, which can be exploited commercially. Four promising CMS hybrids were identified, CMS7 × A4; CMS6 × A4; CMS10 × A4 and CMS2 × CY142 which recorded significant positive heterosis for cured leaf, can enhance the productivity limit set by present cultivars and would be the components for varietal diversification under KLS. Positive significant associations were noticed between plant height and number of leaves per plant, and intermodal length. The study revealed direct positive effect of plant height on cured leaf and negative indirect effect of number of leaves, intermodal length and leaf area suggesting that these characters should be judiciously selected for achieving higher yield.