Additive Gene Action Research Articles

Diallel analysis of soybean (Glycine max L.) for biomass yield and root characteristics under low phosphorus soil conditions in Western Ethiopia.

Combining ability studies under low soil P conditions provides useful information on the inheritance of important traits to improve soybean for low P tolerance. The study aimed at determining the combining ability and gene actions of biomass yield and root traits in soybean under low phosphorus conditions. Nine parental genotypes and their 36 half diallel F2/F3 progenies were evaluated at two locations in Ethiopia on soils of low P availability. Highly significant (P<0.01) general combining ability (GCA) were found for all the traits and specific combining ability (SCA) for root dry weight and root fresh weight; while the SCA effects of all the rest of the traits were significant (P<0.05). The higher relative contributions of GCA over SCA revealed the preponderance of additive gene action in the inheritance of biomass yield, root dry weight, biomass dry weight, root volume, and root fresh weight with respective relative GCA:SCA contributions of (60.6, 39.4), (50.4, 49.6), (54.9, 45.1), (51.1, 48.9), and (52.1, 47.9); while the narrow-sense heritability was high (34.3%) only for biomass yield. Hardee-1 displayed significant (P<0.05) and positive GCA effects for most of the studied traits, and several crosses involving this parent showed superior performances. The traits i.e., biomass yield, biomass dry weight, root volume and root fresh weight showed highly (P<0.001) correlation with grain yield. Thus, breeding programs aiming to improve soybean for biomass yield and root traits under low-P condition can use Hardee-1 as a parent.

Heterosis and Estimation of General and Specific Combining Ability as Base for Selected Superior Recombination of the Some Crossed Cotton Genotypes

The objective of this study was to determine the general and specific combining abilities and heterosis of some cotton genotypes for yield, its components and fiber traits using line x tester mating design. Nine parents (six line and three testers) were crossed in a line x tester mating design in 2020 season. Nine parents along with their eighteen F1 crosses were studied in a randomized complete block design (RCBD) with three replications during 2021 at Sakha. Agricultural. Research. Station. Kafr El-Sheikh, Governorate, Egypt. Based on line x tester analysis, the variance due to genotypes, parents, crosses and parent vs. cross exhibited significant differences (P. 0.01) for most yield, yield components and fiber traits. The variance due to GCA of lines x testers and SCA of line x tester interactions were highly significant for most studied traits, indicating the importance of both additive and non-additive gene actions in controlling these traits. The estimates of GCA and SCA effects revealed that the parent and some crosses were having desirable and significantly GCA and SCA effects, respectively. High mean performances and significantly GCA effects values were observed of line Giza 92, Giza 75 and tester Giza 97 for most studied traits, hence, these parents can be used as for generation superior cotton hybrids. The best values of mean performances, SCA effects and heterosis were found in the combinations Giza 94 x Giza 92, Giza 97 x Suvin for most yield and yield components and the cross Giza 97 x (Giza 75 x Sea) for yield and fiber traits. These crosses are considered as the promising crosses to be used in breeding programs for produce hybrid cotton and improvement for these traits in Egypt.

The valuable heterosis and genetic inheritance of live weight trait by growth hormone gene action in Ongole-grade cattle

The crucial genetic factors of live weight inheritance including breeding value, dominance deviation, heritability and heterosis had not been studied in Ongole-grade cows. This study aims to identify the genotypic components including breeding value, dominance deviation, heritability and heterosis of live weight trait in Ongole-grade cows. A total of 78 blood samples from parental cows and 2 blood samples from parental Ongole-breed bulls were collected to be analyzed for presences of growth hormone (GH) genes. Presences of GH locus in blood samples were screened using PCR-RFLP method involving restricted enzyme Msp1 on agarose-gel (1.2%). Data were analyzed by statistical program in Excel XP. Results showed that the population mean (μ) of cow live weight was 385.98± 2.49 kg. Genetic component inheritance of homozygous genotypes of GH +/+ and GH –/– and heterozygous genotype of GH +/– were dominated by dominance gene action, rather than the additive gene action resulting the valuable heterosis for live weight trait of 3.2 percent. The heritability of dominance gene action (hD 2 ) was 0.96 categorized as higher heritability, while heritability of additive gene action (hA 2 ) was 0.04 categorized as low heritability under the equilibrium frequencies of both GH + (p = 0.48) and GH – (q = 0.52) genes without considering the nongenetic causes of environmental effect in the population of cow live weight.

Genetic variability, genetic advance and heritability of black and brown seeded soybean [Glycine max (L.) Merrill] lines in Jimma and Bonga Southwest Ethiopia

An experiment was conducted with a simple lattice design with two replications to estimate the genetic variability in 62 soybean genotypes and 2 standard check varieties. The variability parameters such as mean, range of variation, genotypic and phenotypic coefficient of variation, heritability in the broad sense, genetic advance, and genetic advance as percentage of mean were estimated for 11 different traits. The values of the phenotypic coefficient of variation (PCV) were greater than the genotypic coefficient of variation (GCV) for all the traits, revealing the influence of environmental factors. The value of heritability was determined to be high for the traits such as grain yield, harvest index, number of seeds per pod, number of primary branches per plant, number of pods per plant and hundred seed weight. Indicating that the larger portion of total variation would be under genetic control and selection based on phenotypic levels would be useful for the improvement of these traits in soybean. High estimates of heritability together with high genetic advance as percentage of mean were recorded for grain yield, harvest index, number of seeds per pod, number of primary branches per plant, number of pods per plant and hundred seed weight, which may be attributed to the presence of additive gene action and had high selective value. Thus, selection pressure could successfully be applied to these traits for soybean improvement programs. Int. J. Agril. Res. Innov. Tech. 12(2): 14-17, December 2022

Genetic analyses of tropical maize lines under artificial infestation of fall armyworm and foliar diseases under optimum conditions.

Development and deployment of high-yielding maize varieties with native resistance to Fall armyworm (FAW), turcicum leaf blight (TLB), and gray leaf spot (GLS) infestation is critical for addressing the food insecurity in sub-Saharan Africa. The objectives of this study were to determine the inheritance of resistance for FAW, identity hybrids which in addition to FAW resistance, also show resistance to TLB and GLS, and investigate the usefulness of models based on general combining ability (GCA) and SNP markers in predicting the performance of new untested hybrids. Half-diallel mating scheme was used to generate 105 F1 hybrids from 15 parents and another 55 F1 hybrids from 11 parents. These were evaluated in two experiments, each with commercial checks in multiple locations under FAW artificial infestation and optimum management in Kenya. Under artificial FAW infestation, significant mean squares among hybrids and hybrids x environment were observed for most traits in both experiments, including at least one of the three assessments carried out for foliar damage caused by FAW. Interaction of GCA x environment and specific combining ability (SCA) x environment interactions were significant for all traits under FAW infestation and optimal conditions. Moderate to high heritability estimates were observed for GY under both management conditions. Correlation between GY and two of the three scorings (one and three weeks after infestation) for foliar damage caused by FAW were negative (-0.27 and -0.38) and significant. Positive and significant correlation (0.84) was observed between FAW-inflicted ear damage and the percentage of rotten ears. We identified many superior-performing hybrids compared to the best commercial checks for both GY and FAW resistance associated traits. Inbred lines CML312, CML567, CML488, DTPYC9-F46-1-2-1-2, CKDHL164288, CKDHL166062, and CLRCY039 had significant and positive GCA for GY (positive) and FAW resistance-associated traits (negative). CML567 was a parent in four of the top ten hybrids under optimum and FAW conditions. Both additive and non-additive gene action were important in the inheritance of FAW resistance. Both GCA and marker-based models showed high correlation with field performance, but marker-based models exhibited considerably higher correlation. The best performing hybrids identified in this study could be used as potential single cross testers in the development of three-way FAW resistance hybrids. Overall, our results provide insights that help breeders to design effective breeding strategies to develop FAW resistant hybrids that are high yielding under FAW and optimum conditions.

Evaluation of some genetic variability associated traits of 32 rice (Oryza sativa L.) genotypes in three different planting spacing by path coefficient analysis

The study was taken up to estimate 32 advance breeding lines of rice for grain yield and the related traits in three different planting techniques, viz. direct seeded condition (E-I), transplanting with spacing of 15 x 15 cm (E-II) and 25 x 15 cm (E-III). The experimentation was carried out to explore the parameters of hereditary &amp; variability for yield along-with yield components, to study the extent of association and direct and indirect special effects of different yield components on grain yield in rice. The analysis of variance from the experimental results documented significant changes amongst various genotypes for all studied traits with respect to the three planting spacing. High GCV, high magnitude of broad sense heritability coupled with genetic advance as percentage of mean was detected for grain yield/plant and harvest index. These above-mentioned traits displayed considerable contribution of different additive gene action for their phenotypic appearance. The characters harvest index (%), biological yield/plant, flag leaf angle and no. of productive tillers/plant showed positive correlation &amp; direct effect on grain yield per plant on pooled analysis. It indicated that these traits might be included in formulating criteria of selection for enhancement of the grain yield per plant in rice.

Use of Graphical and Numerical Approaches for Diallel Analysis of Grain Yield and Its Attributes in Bread Wheat (Triticum aestivum L.) under Varying Environmental Conditions

Improving yield is the main aim of plant breeders. In the case of bread wheat (Triticum aestivum), a major challenge in this regard is genotype–environment interactions, and a knowledge of these is required to successfully select high-yielding genotypes. In this study, graphical and numerical approaches of diallel analysis have been used to reveal such interactions. Ten different wheat genotypes were crossed using a half-diallel approach. The parents, hybrids, and standard checks were evaluated at the Regional Research Station, Anand Agricultural University, Gujarat, Anand, India under both standard and late-sown conditions in two separate years (E1 and E2 (normal-18 November 2018 and late sown-10 December 2018, respectively, Rabi 2018–2019), E3 and E4 (normal-18 November 2019 and late sown-10 December 2019, respectively, Rabi 2019–2020)). For each sowing, ‘t2’ values were calculated for eleven phenotypic characteristics: days to 50% heading, days to maturity, plant height, number of effective tillers per plant, length of main stem, number of spikelets per main spike, number of grains per main spike, grain yield per main spike, grain yield per plant, 1000-grain weight, and harvest index. Components of the gene effect revealed that the number of spikelets per main spike in E2 and E4, and the number of grains per main spike in E2 were governed by both additive and dominance gene action across the environments. Other characteristics were the greater influence of the dominance gene effect, except for days to 50% heading in E1, E2, E3, and E4; days to maturity in E2, E3, and E4; grain yield per main spike in E4. Many characteristics exhibited overdominance, an asymmetrical distribution of positive–negative, dominance–recessive genes, and narrow-sense heritability in all environments. In graphical analysis, regression value ‘b’ was unity for days to 50% heading (E1 and E4) and 1000-grain weight (E3 and E4), which revealed an absence of digenic interactions for these characteristics in the respective environments. Therefore, a given population may be improved to isolate superior recombinants for the development of desired parents in future breeding programs.

Assessment of Genetic Variability Parameters Among the F2 Population of a Cross Between Jaya × Isogenic Line of MTU1010 for Yield and its Component Traits in Rice

An experiment was carried out during Rabi 2021-22 at the experimental plot of ICAR-Indian Institute of Rice Research, Hyderabad. Two diverse elite indica lines of rice (Jaya and isogenic line of MTU1010) were used to generate the F2 population to study genetic variability parameters, heritability, and expected genetic advance under selection. Higher GCV, PCV, and heritability coupled with high genetic advance were estimated for the number of productive tillers, panicle weight, number of filled grains, and single plant yield, which indicated that heritability of these traits was under the control of additive gene action. Stringent selection for such traits will be rewarding.

Combining ability studies of grain Fe and Zn contents of pearl millet (Pennisetum glaucum L.) in West Africa.

Micronutrient malnutrition is a major challenge in Africa, where half a million children die each year because of lack of micronutrients in their food. Pearl millet is an important food and fodder crop for the people living in the Semi-Arid regions of West Africa. The present study was conducted to determine the stability, combining ability, and gene action conditions of the high level of Fe and Zn content in grain and selected agronomic traits. Hence, eight genotypes were selected based on the availability of grain Fe and Zn contents and crossed in a full diallel mating design. Progenies from an 8 × 8 diallel mating along with the parents were evaluated in an alpha lattice design with three replications in three locations for two years. The parental lines Jirani, LCIC 9702 and MORO, had positive significant general combining ability (GCA) effects for grain Fe concentration, while Jirani and MORO had positive significant GCA effects for grain Zn concentration. For the specific combining ability (SCA), among the 56 hybrids evaluated, only the hybrids LCIC 9702 × Jirani and MORO × ZANGO had positive significant SCA effects for grain Fe concentration across locations, and for grain Zn concentration, the hybrids Gamoji × MORO, LCIC 9702 × Jirani, and ICMV 167006 × Jirani had positive significant SCA effects. The reciprocal effects were significant for grain Zn concentration, grain yield, flowering time, plant height, test weight, and downy mildew incidence, suggesting that the choice of a female or male parent is critical in hybrid production. Grain Fe and Zn concentration, flowering time, plant height, panicle length, panicle girth, panicle compactness, and downy mildew incidence were found to be predominantly under additive gene action, while grain yield and test weight were predominantly under non-additive gene action. A highly positive correlation was found between grain Fe and Zn concentrations, which implies that improving grain Fe trait automatically improves the grain Zn content. The stability analysis revealed that the hybrid ICMV 167006 × Jirani was the most stable and high-yielding with a high level of grain Fe and Zn micronutrients.

Genetic Variability Studies in Advanced Breeding Lines of Brinjal (Solanum melongena L.) for Fruit Yield and Quality Parameters

An experiment was carried out to assess genetic variability in thirty advanced breeding lines of brinjal during Rabi season 2021-2022 at the College of Horticulture, Mudigere. The experiment was laid out in randomized complete block design with three replications. Analysis of variance indicated the presence of large variability for different characters under study. The genotypic coefficient of variation and phenotypic coefficient of variation was high (&gt;20 %) for the number of primary branches at 30 DAT, average fruit weight, whereas, plant height at 30 and 90 DAT, number of primary branches at 90 DAT, stalk length, fruit yield per plot, estimated fruit yield per hectare, dry matter content and fruit phenol content showed moderate GCV and PCV. High heritability coupled with high genetic advance (&gt;20 %) in per cent of mean were recorded for plant height at 30 DAT, number of primary branches at 30 and 90 DAT, days to first flowering, average fruit weight, stalk length, fruit yield per plot, estimated fruit yield, dry matter content and fruit phenol content indicating that these traits are controlled by additive gene action. Therefore, studied characters may be included in assortment criterion for improvement in fruit yield per plant and yield contributing traits.

Heterosis and Combining Ability Studies in A 5x5 Diallel Crosses of Maize Inbred Lines

The present study was conducted to evaluate the genetic architecture of five diverse maize genotypes using combining ability analyses. General combining ability (GCA) mean squares were non-significant for grain yield and its related components. Specific combining ability (SCA) mean squares were highly significant for grain yield, the number of grains per row and cob girth while non-significant for days to tasseling, days to silking, plant height, cob height and cob length. These studies suggested the preponderance of non-additive type of gene action for grain yield, cob girth and number of grains per row and additive gene action for days to tasseling, days to silking, plant height, cob height and cob length. The genotypes MIL2020-51 and MIL2020-52 were good general combiners for grain yield, grains per row, cob height and plant height. These lines were the poorest general combiner for days to 50% tasseling and days to 50% silking which suggested that these genotypes had sufficient genes for inducing earliness. The crosses MIL2020-51 x MIL2020-54, MIL2020-52 x MIL2020-53, MIL2020-51 x MIL2020-55, MIL2020-53 x MIL2020-55and MIL2020-52 x MIL2020-55 were the best performing combinations for grain yield. These crosses involved good x good and good x poor general combiners. The reciprocal cross combinations MIL2020-55 x MIL2020-53, MIL2020-52 x MIL20220-51, MIL2020-54I x MIL2020-52, MIL2020-55 x MIL2020-51, MIL2020-54 x MIL2020-51and MIL2020-55 x MIL2020-54 showed large positive estimates for grain yield suggesting that cytoplasmic inheritance also had a role in the expression of grain yield. SCA variances were higher than GCA variances for grain yield, plant height, cob height, number of grains per row, cob girth and cob length which highlighted major role of non-additive genes in the inheritance of these traits. Additive gene action was found more important for number of days to 50% tasseling and number of days to 50% silking

Recent Advances in Breeding Maize for Drought, Heat and Combined Heat and Drought Stress Tolerance in Sub-Saharan Africa

Abstract Drought, heat, and combined drought and heat are important abiotic stresses constraining the production and productivity of maize ( Zea mays L.) in sub-Saharan Africa (SSA). In the face of climate change, these stresses are likely to occur simultaneously and put at risk food and economic security in SSA. This review describes maize breeding activities conducted by the International Institute of Tropical Agriculture (IITA) in partnership with national scientists under the Drought Tolerant Maize for Africa (DTMA) and Stress Tolerant Maize for Africa (STMA) projects, which together sought to develop and deploy multiple stress tolerant hybrids, and open-pollinated varieties. Emphasis was on (i) developing a reliable methodology for screening maize for tolerance to drought stress (DS), heat stress (HS), and combined drought and heat stress (CDHS) using key secondary traits and grain yield, (ii) use of appropriate breeding techniques for tailoring maize for tolerance to DS, HS and CDHS, (iii) exploring diverse sources of germplasm for genetic enhancement of maize, (iv) extensive multilocational evaluation to identify genotypes with stable performance under the stresses, and (v) application of genomic tools to accelerate genetic gains in maize breeding at IITA. At IITA, the performance of maize hybrids under stresses of DS, HS and CDHS have been improved using conventional breeding techniques/procedures. These techniques/ procedures have led to accelerated genetic gains in yield that were 26–49% higher than the best commercial hybrid checks under CDHS and DS. Additive gene action has been consistently found to be more important than the non-additive among early maize under DS and CDHS while both the additive and non-additive have been reported to be important for the extra-early maize. The most reliable secondary traits for selecting for improved grain yield under the stresses include anthesis-silking interval, ears per plant, and plant and ear aspects. Several early and extra-early landraces have been identified as potential sources of tolerance to DS, HS, and CDHS. Several quantitative trait loci (QTLs) associated with grain yield and key secondary traits have been identified via genome-wide association studies in landraces and inbred lines. Those desirable QTLs, upon validation, could be invaluable for genomics-enabled breeding.

Studies on Genetic Variability, Heritability and Genetic Advance in Garden Pea (Pisum sativum L.) Genotypes under the Central Dry Zone of Karnataka, India

A field experiment was carried out to determine the genetic variability, heritability and Genetic advance present in twenty-two genotypes of garden pea during Rabi season 2021-22 at ICAR-Krishi Vigyan Kendra, Babbur farm, Hiriyur. The experiment was laid out in Randomized Complete Block Design with two replications. Observations were recorded on various yield and yield contributing characters. In general, the magnitude of the phenotypic coefficient of variation (PCV) was greater than that of the genotypic coefficient of variation (GCV) and the narrow difference between them indicates less environmental influence on the expression of the trait. High PCVand GCV (&gt;20%) were recorded on plant height, number of branches per plant, pod thickness, number of pods per plant and non-reducing sugars which indicates the presence of high genetic variation and scope for effective improvement. All the characters studied in this experiment showed high heritability (&gt;60%) in a broad sense coupled with high genetic advance as per cent over a mean (&gt;20%) except for days to first flowering, days to 50 per cent flowering and days taken for first picking. This indicates the existence of additive gene action and the need for population improvement through selection. The genotypes that exhibit specific traits can be used in a hybridization programme

Identifying prominent genotypes and yield contributing traits in finger millet (Eleusine coracana L.)

The knowledge about genetic variability and determining the criteria for employing effective selection is always prerequisite to develop a sound breeding programme. Therefore, the present experiment was conducted with 35 genotypes of finger millet in Randomized Block Design (RBD) with three (03) replications and observations were recorded for morphological and quality traits. The analysis of variance exhibited substantial degree of variability among the genotypes for all the traits under study. The higher value of phenotypic coefficient of variance (PCV) than genotypic coefficient of variance (GCV) for all the traits under study indicated the influence of environment on expression of these traits. High heritability coupled with high genetic advance as percent of mean suggested that direct selection for the traits viz. iron content, test weight, calcium content, finger length, protein content, flag leaf area and days to 80% maturity may be carried out as these traits have preponderance of additive gene action. Similarly, character association results depicted that direct selection for the traits viz. flag leaf area, test weight, biological yield/plant, harvest index and iron content will be effective for tangible advancement in grain yield of this important millet. Further, Genetic divergence study for identifying such promising genotypes revealed that among the seven clusters, Cluster III and cluster VII were most divergent hence genotypes viz., MLS 1, MLS 5, GPU 67, VL 376 and Indira Ragi from these clusters may throw useful segregates in upcoming generations.

Elucidation of genetic variability, heritability, correlation and path coefficient in carrot (Daucus carota L.)

An experiment was conducted at the Punjab Agricultural University, Ludhiana, India, for 2 years (2019-20 and 2020-21), to study the genetic variability, heritability, correlation and path coefficient analysis in 28 genotypes of Asiatic carrot under 8 environments. The experiment was laid out in RBD with three replications. The analysis of variance showed that the genotype’s mean sum of squares was significant for all the traits studied, indicating that significant variation existed among them. A wide range of variation existed for average root length, root weight, root diameter, core diameter and root shoot ratio i.e., 14.5-21.0 cm, 40.9-77.8 g, 2.2-2.7 cm, 0.93-1.56 cm and 0.86 to 1.29, respectively. The average marketable yield of genotypes ranged between 365.55 to 584.55 q ha-1. Vegetative traits like shoot length varied from 42.0-64.7 cm, shoot weight from 44.71-80.14 g, and the number of leaves from 5.4 -7.2 among all genotypes. The magnitude of phenotypic coefficient of variation was greater than the corresponding genotypic coefficient of variation for all the traits indicating that trait expression is environmentally influenced. Root-shoot ratio, shoot length, number of leaves, root length, and root diameter all have exhibited highest heritability and moderate genetic advance that suggested additive gene action. Strong character association of root length, root diameter and root weight with marketable yield suggested as selection criteria for higher yield.

Interrelationship among elite germplasm of cucumber (Cucumis sativus L.) at genotypic and phenotypic level

The experiment was conducted to work out variability, heritability, genetic advance and interrelationship using twelve genotypes of cucumber (Cucumis sativus L.). GCV and PCV were highest for number of fruits per vine; whereas lowest estimate was recorded for days to first harvesting and days to last harvesting. The high heritability showed by vine length and number of fruit per vine and as compare to other characters, whereas days to last harvesting, showed lower value of heritability. Genetic advance in percentage of mean was found highest for number of fruits per vine show that these characters are under the control of additive gene action and that environmental factors have a lesser influence on the expression of these traits, thus further development of these traits through direct selection. The path coefficient analysis revealed high and positive direct is possible effect on fruit weight and days to last harvesting. As a result, these traits turned out to be important components of fruit yield thus direct selection effective via these two traits.

Utilizing genetic variability parameters of garden pea (Pisum sativum L.) germplasm for yield and quality traits

In present study, 159 diverse pea genotypes were evaluated at Vegetable Research Farm, Punjab Agricultural University, Ludhiana, Punjab, India to study genetic variability, heritability and genetic advance involving 14 morphological traits. The analysis of variance showed significant differences among genotypes for all the traits under study except node at which 1st pod appears. On the basis of mean performance, the maximum yield was observed in PB-90 which was followed by PB-89 and 2009/PMVAR-6. Highest coefficient of variation was observed for number of seeds/pod and highest genotypic and phenotypic coefficients of variation were recorded for number of pods/plant followed by plant height and total yield/plant. Very high heritability estimates were observed for plant height (99.89) followed by total yield/plant (99.71) and days to 1st picking (99.43) while genetic advance as percent of mean was observed high for number of pods/plant (65.35) followed by plant height (58.66) and total yield/plant (42.17). High heritability along with high genetic advance was found for all traits under study. High heritability estimates coupled with high genetic advance reflects the presence of additive gene action for expression of these traits.

Genetic Diversity, Heritability, Genetic Advance of Growth and Yield Traits of Some Okra (Abelmoschus Esculentus L. Moench) Accessions

Genetic improvement of okra for yield is significant to overcome the low genetic potential of the existing varieties and environmental factors which are the major constraints to okra yield. This study was carried out to understand the genetic nature of yield and its components on which selection can be made. The seed of each accession was sown in a plot laid out in randomised complete block design with three replications. Data were collected on fifteen agronomic characters and analysed. The magnitude of phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were highest for number of pods and lowest for number of days to germination respectively. The PCV was moderately higher than GCV in most of the traits studied, which indicated that environment played a little role in the expression of these traits. Low heritability was recorded for number of leaves and number of branches which indicated more influence of environmental effect, which may be due to the presence of non-additive gene action in the expression of the traits. High heritability and high genetic advance as percent of mean were recorded for plant height at flowering, days to 50% flowering, plant height at maturity, internode length, number of pods and days to maturity, indicating that these traits were less influenced by environment and presence of additive gene action. NGB00378A, NGB00299, NGB00304 and NGB00302 had higher fruit yields; flowered earlier, had longer harvesting period. Therefore, selection can be made on these for further improvement of this crop.

Genetic variability studies in F2 segregating population of indeterminate tomato (Solanum lycopersicum L.) genotypes under protected conditions

A field study under protected conditions was conducted to assess genetic variability for yield and yield attributes in an F2 segregating population of tomato cross EC521069× EC362941. The experiment was carried out during 2021–2022 at the College of Horticulture, Mudigere, in an augmented block design. Analysis of variance showed highly significant differences among the traits. High values of PCV and GCV were registered for number of fruits per plant, fruit yield per plant, fruit volume and average fruit weight. Estimates of high heritability coupled with high genetic advance as per cent over mean recorded for plant height, number of flowers per cluster, days taken from first harvest to last harvest, fruits per cluster, fruits per plant, fruit yield per plant, fruit length, fruit diameter, fruit volume, average fruit weight and pericarp thickness which supports the notion that selection could actually improve these traits by highlighting the significance of additive gene action.

Genetic variability study in advanced mutant lines of cluster bean [Cyamopsis tetragonoloba (L.) Taub.

Advanced cluster bean mutant lines developed by treating seeds of Pusa Navbahar variety with gamma radiation were evaluated in randomised complete block design with two replications to study the genetic variability. The analysis of variance revealed highly significant differences among the mutant lines of cluster bean for all the characters studied. The GCV and PCV values were high (&gt;20 %) for number of vegetable pods per plant, pod yield per plant, pod yield per plot, pod weight, dry pod yield per plant, seed yield per plant and seed yield per plot indicating the existence of broad genetic base, which would be amenable for further crop improvement. High heritability (&gt;60 %) coupled with high genetic advance over mean (&gt;20 %) were observed for characters viz., plant height, number of vegetable pods per plant, number of pods per cluster, pod yield per plant and seed yield per plant which indicated predominance of additive gene action for these traits and hence direct selection would be more effective in improving these traits.