Non-allelic Interaction Research Articles

Genetic effects on panicle traits of crossbred rainfed rice cultivars using generation mean analysis

The nature and magnitude of gene effects involved in expression of panicle traits in rainfed rice cultivars were estimated among a wide range of crosses using generation mean analysis. The parental lines comprised of two low-land and six upland rain-fed rice. The lowland parents were used as pollen parents and the upland genotypes were maintained as the seed parents. Crosses were made between them to obtain the F1 hybrids. Backcrosses were produced by crossing the F1 hybrids to their pollen parent to obtain BC1.1 and seed parents to produce BC1.2. The result revealed significant differences (P ≤ 0.05) among the genotypes for all the characters studied. Except for Max x CT7127-49 where P2 and F2 plants of WITA 4 x NERICA 1 that produced long panicles (29.28 and 26.13 cm) that differed significantly (P ≤ 0.05) from other generations, F1 plants produced the longest panicles in the other crosses followed by the F2 plants. For most traits, F1 generation means were higher than the mid-parent values. Significant differences observed between the F1 and F2 generation means in majority of the cases for percentage fertile spikelet and spikelet number per panicle is thought to be due to the diversity in these traits among the parental lines. The means of BC₁ and BC2 tended to be located close to those of their respective recurrent parents. Digenic epistatic model was adequate to explain variation in generation means for all the panicle traits for the pooled analysis. Most of the crosses manifested non-allelic interactions for number of spikelet per panicles and fertile spikelet per panicle and is an indication that epistasis is determined to some extent by the genotypes used for the study. Key words: Generation mean, dominance, additive, epistasis, F1, F2, parental line and backcross.

Nature of gene action for yield and its components in mungbean (Vigna radiata)

The assessment of gene effect for some yield characters and detection of epistasis in mungbean [Vigna radiata (L.) Wilczek] was studied in four crosses involving five parents through generation mean analysis during kharif 2012 at Banaras Hindu University (BHU), Varanasi, UP. Six populations, viz. P1, P2, F1, F2, B1 and B2 of four crosses involving five parents were evaluated. The nature and magnitude of gene effects for yield and its components in mungbean was studied using six parameter model of generation mean analysis. The presence of epistasis was detected by joint scaling test and inadequacy of additive-dominance model was established except seeds/pod. Additive (d), dominance (h) gene effects along with one or more type of non-allelic interactions (i, j, l) contributed significantlytowards the inheritance of all the quantitative characters in majority of the crosses. Duplicate type of epistasis andpredominant dominance effects was also prevalent in most of the cases except in days to maturity in HUM 8 x ML 713 cross. Thus, postponement of selection in later generations may be suggested to obtain transgressive segregants for improvement of mungbean populations.

Gene effects and genetic analysis of indigenous land races and improved cultivars for yield and yield components in rice (Oryza sativaL.)

Rice is one of the crucial staple food crops and its unique grains assist to hold two third of world population. Generation mean analysis is commonly used in studies of inheritance of quantitative traits. Experimental material consisted of ten parents which included six high yielding varieties used as female parents and four traditional landraces used as male parents, F1, F2 and F3generation of six crosses viz., IR 72 x Veeradangan, ADT 39 x Kavuni, ADT 45 x Kavuni, ADT 43 x Navara, ASD 16 x Navara and TPS 4 x Kathanellu. Seven biometrical characters indicated that additive and dominance x dominance gene actions were predominant with duplicate type of gene action for five biometrical characters viz., plant height, number of productive tillers per plant, panicle length, number of filled grains per panicle and single plant yield. The epiststic effects, additive x additive [i] and dominance x dominance [h] were highly significant in most cases. The signs of (h) and (l) were opposite in all studied traits for most crosses. Non-allelic gene interaction was operating in the control of genetic variation in most studied traits. Also, the inheritance of all studied traits was controlled by additive and non-additive genetic effects, but dominance gene effects play the major role in controlling the genetic variation of the most studied traits. Present study indicated that early generation selection is effective and should be practiced for future breeding program.

Genetic and molecular characterisations of Tomato leaf curl virus resistance in tomato (Solanum lycopersicum L.)

SUMMARYFour different F2 populations were developed involving Solanum habrochaites accession ‘EC-520061’ that is highly resistant to Tomato leaf curl virus (ToLCV) disease and four ToLCV-susceptible cultivars of tomato (S. lycopersicum L.), ‘Punjab Chhuhara’ (PBC),‘H-24’, ‘H-86’, and ‘DVRT-2’.The segregation ratios of tomato leaf curl disease development in all four F2 populations were 13:3 (resistant:susceptible), indicating a dominant inhibitory gene for leaf curl disease resistance, and 3:1 (indeterminate:determinate) indicating a single dominant gene for plant growth habit. The patterns of inheritance were shown to be additive with dominant non-allelic gene interactions for the traits of ToLCV resistance and fruit yield. Using bulk segregant analysis (BSA) and one of the F2 populations (‘PBC’ X ‘EC-520061’) above, two SSR markers (SSR218170–145 and SSR304158–186) were identified for ToLCV resistance. The SSR marker SSR218170–145 was located at 15 cM on chromosome 10, and the marker SSR304158–186 was located at 35 cM on chromosome 7. This study will support the development of new ToLCV- resistant tomato varieties via breeding programmes.

Inheritance of low erucic acid in Indian mustard [Brassica juncea(L.) Czern. and Coss.

Genetics of erucic acid content was studied using six generations viz., P1, P2, F1, F2, B1 and B2 derived from the crosses, Varuna × LES-39 and Varuna × LES-1-27. The trait high erucic acid content was partially dominant over low erucic acid content in both the crosses. In both the crosses, adequacy of additive – dominance model suggested absence of non-allelic interactions. The study revealed that selection for low erucic acid would result in isolation of plants with high oleic and linoleic acids and hence, it should be possible to develop high oleic acid lines having low erucic acid content in mustard.

Assessment of Genetic Architecture of Grain Yield and its Component Traits in Barley (Hordeum vulgareL.) through Generation Mean Analysis

The suitable breeding procedure for crop improvement mainly depends on knowledge of the genetic make-up of the character to be selected. Unique architectural phenotypes have the vast potential for increasing the yield of the crop. Therefore, the investigation was carried out during three successive seasons Rabi 2009–10, 2010–11 and 2011–12 at Agriculture Research Farm, Banaras Hindu University, U.P. India with objective to estimate the main genetic effects including digenic non-allelic interactions controlling yield and yield component traits as-well-as to determine the yield component that affects yield to a greater extent. The generation mean analysis was carried out on six generations (P1, P2, F1, F2, B1 and B2) in six crosses involving two tester (LAKHAN and BH-902) and three exotic lines (MOROC-9-75, BEECHER and HARMAL) of barley. Duplicate type of epistasis was found for most of the traits in certain cross combinations, whose effect can be wiped out by following sophisticated selection procedure such as reciprocal recurrent selection and/or biparental mating in early segregating generations for the development of high yielding barley varieties with desirable yield contributing traits.

Gene action for quantitative traits through Generation means analysis in sesame (Sesamum indicum)

Understanding the nature of gene action in the breeding material is helpful for breeders in formulating breeder strategy. In order to understand the type of gene action operating in the breeding materials six generation means (P1, P2, F1, F2, BC1 and BC2) from five crosses were used to estimate the genetic effects of yield and some quantitative traits in sesame (Sesamum indicum L.) The analysis showed the presence of additive, dominance and epistatic gene interactions. The additive dominance model was adequate for capsule length in the KMR 108 × JCS 507 and KKS 98049 × IS 562 B crosses. An epistatic digenic model was assumed for the remaining crosses. Duplicate- type epistasis played a greater role than complementary epistasis. The study deciphered that simple additive dominance model exhibited lack of good fit for all the traits in five crosses studied, indicating the role of non-allelic interactions. Dominance and epistatic interactions played a major role in the inheritance of yield and yield contributing characters in sesame. It can be categorically stated that reciprocal recurrent selection or diallel selective mating system are the need of the hour to modify the genetic architecture of sesame for attaining higher yields with desirable oil content.

Genetic Study and QTL Mapping of Seed Glucosinolate Content in Brassica rapa L.

ABSTRACTSelf‐incompatibility in Brassica rapa L. is a major impediment to experimental studies on the genetic control of quantitative traits such as seed glucosinolate (GSL) content. In this paper, we report quantitative trait loci (QTL) mapping of total seed GSL content using a recombinant inbred line (RIL) population derived from two self‐compatible high‐ and low‐GSL B. rapa grown under different environmental conditions. Furthermore, quantitative genetic analysis using the parents and their F1, F2, B1 (F1 backcrossed to high‐parent P1), B2 (F1 backcrossed to low‐parent P2), and self‐pollinated progenies of B1 generation populations are also reported. Quantitative genetic analysis showed that additive genetic variance was consistently significant under different environments, while the dominance effect was significant under one growth condition. However, a simple additive‐dominance model was inadequate to explain the segregation variation among the generation means. Nonallelic interaction effects were important in the genetic control of GSL content in early generations where the levels of heterozygosity remained high. QTL mapping detected three loci at the linkage groups A2, A7, and A9 involved in the control of this trait. These QTL individually explained 5 to 22% of total phenotypic variation. The QTL on A9 was detected in all environments and explained 22%, the greatest amount of phenotypic variation. No additive × additive gene interaction was detected based on QTL analysis, and this also largely agreed with quantitative genetic analysis. Similarly, the number of loci detected based on QTL mapping also agree with the results obtained from quantitative genetic analysis.

Genetics of Fruit Quality in Okra (Abelmoschus Esculentus) under Waste Water

A field experiment consists of five genotypes of okra was conducted in the research area of the Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad during crop season 2010-2011.All possible crosses were made to obtain F1seed following diallel analysis design. The F1 seed along with their parents was evaluated. The experiment was laid out in randomized complete block design. Data was collected for some quality traits as protein content, dietryfiber content and carbohydrates. The numerical approaches demonstrated that dietary fiber contents and carbohydrate contents under wastewater irrigation were ruled by over-dominance with non-additive type of gene action while partial dominance was observed in protein contents under wastewater irrigation, dietary fiber contents and carbohydrates under normal irrigation water which suggested that early selection might end up in improving these genotypes. Non-allelic interaction or epistasis was absent for all the traits studied. It indicated thatselection in early generations for these traits would be difficult.

Inheritance of Yield and its Related Traits in Bitter Gourd (<i>Momordica charantia</i> L.)

A study on understanding the inheritance of yield and its related traits in bitter gourd by using generation means analysis involving six generations in two crosses (IC-044417×IC-045339 and IC-045339×IC-470560) revealed the presence of non-allelic interaction effects in expression of all the traits studied. All the traits were inherited by dominance ( h ) among the main effects and additive×additive ( i ) among the interaction effects in IC-044417×IC-045339 while dominance, additive×additive ( i ) and additive×dominance ( j ) in IC-045339×IC-470560 except fruit girth which was inherited by dominance ( h ) and dominance×dominance ( l ) type of interaction effect. Therefore, recurrent selection and diallel selective mating system in addition to heterosis breeding may be used to improve the traits in bitter gourd.

The mode of inheritance and gene effects for spike length in different wheat genotypes

In this work were selected five wheat varieties (Pobeda, Renesansa, Sara, Partizanka and Pesma) in order to analyze the gene effects and the mode of inheritance of spike length. The above mentioned varieties were diallel crossed and F1, F2, and Fbc1 was produced. The gene effects were estimated using additive-dominance model which was adequate for two crossing combination Pobeda/Renesansa and Renesansa/Sara. In most crosses the value of dominant gene effect was more significant than additive. The inheritance of the spike length was influenced by additive x additive and dominance x dominance type of non-allelic interactions. In the most number of cases, inheritance of spike length was expressed domination.

Study on gene action, heterosis and inbreeding depression for yield and quality traits in castor (Ricinus communis L.)

Gene action, heterosis and inbreeding depression study for yield and quality traits in castor (Ricinus communis L.) was carried out through six parameter generation mean analysis at Main Castor-Mustard Research Station, Sardarkrushinagar Dantiwada Agricultural University (SDAU), Sardarkrushinagar (SK Nagar). The experimental material included six families (P1, P2,F1,F2, BC1, BC2) of six crosses SH 72 x PRT 44, SKI 215 x SKI 166, PCS 124 x 37504, PCS 124 x JH 118, SKI 1 x JH 118 and HC 8 x JH 118. The charactersstudied were daysto flowering, daysto maturity,stemlength, number of nodes onmain stem, effective length of primary raceme, number of capsules on primary raceme, number of effective branches/plant, seed yield/plant, 100-seed weight, oil content in seed, endosperm content, oil content in endosperm, palmatic acid content, oleic acid content, linoleic acid content, linolenic acid content and ricinoleic acid content. The analysis of variance showed significant differences between all the generationsin majority ofthe characters ofthe crosses. The estimation ofscaling testsshowed that non-allelic interactions played an important role in the genetic control of all the characters. All the generations differed significantly for their mean(m) performance of all the traits. The estimates of gene effectsrevealed that both additive and non-additive gene actions were important for days to flowering, days to maturity, stem length, number of nodes on main stem, effective length of primary raceme, number of capsules on primary raceme, number of effective branches/plant, endosperm content, 100-seed weight, seed yield/plant, oil content in seed, linoleic acid content, linolenic acid content and ricinoleic acid content. Whereas, non-additive as well as epistatic gene actions were important for oil content in endosperm, palmatic acid content and oleic acid content. Crosses showing low heterobeltiosis effects also displayed high inbreeding depression for seed yield/plant in general. Utilization of biparental mating and reciprocal recurrent selection schemes which has the virtue of effectively exploiting, both additive and non-additive components, was suggested for exploiting present set of materials for obtaining high yielding genotypes of castor.

Inheritance of Resistance to Powdery Mildew Race 2 in Citrullus lanatus var. lanatus

Information on the mode of inheritance of powdery mildew resistance in watermelon is important for designing a breeding strategy for the development of new cultivars. Resistance in the watermelon accession PI 270545 was investigated by generation means analysis by crossing it with susceptible PI 267677. The analyses showed involvement of two genes, a recessive resistance gene, pmr-1, and a dominant gene for moderate resistance, Pmr-2. Resistance to powdery mildew in the leaf had a large dominance effect and a heritability of 71%. The additive-dominance model was inadequate in explaining variation in leaf resistance as revealed by the joint scaling test. However, nonallelic interactions could not be detected by the nonweighted six-parameter scaling test. For stem resistance, the additive-dominance model was adequate, and inheritance was controlled mainly by additive effects. A high narrow-sense heritability of 79% suggested that selection for stem resistance in early generations would be effective.

Diallel cross analysis of filament length in the silkworm, Bombyx mori L.

A diallel analysis for filament length in six varieties of silkworm, Bombyx mori L. having a wide range of variability has been genetically analysed by means of 6×6 diallel cross. The results indicated that both additive and non-additive genetic variations were important for determining the expression of this trait. Besides the dominance, deviation of genes present in this diallel existed predominantly in one direction and they were independent of reciprocal effect and some of the parents contained more dominant than recessive alleles in S-1 and S-3. The presence of specific dominance effect which were peculiar to individual crosses and a significant part of it was independent of reciprocal effect. The regression of filament length is deviated significantly from unity in majority of the seasons (except S-4) giving a contrasting result implying the presence of nonallelic interaction. The distribution of genes for two seasons (S-2 and S-3) was not symmetrical, while the rest two seasons (S-1 and S-4) showed symmetrical distribution of positive and negative among the parents. In narrow sense heritability was found to be medium to high and the broad sense heritability was high among the studied varieties. DOI: http://dx.doi.org/10.3329/jasbs.v38i2.15616 J. Asiat. Soc. Bangladesh, Sci. 38(2): 247-255, December 2012

GENETIC SYSTEM CONTROLLING THE YIELD AND ITS COMPONENTS IN THREE BREAD WHEAT (TRITICUM AESTIVUM, L.) CROSSES

This investigation was carried out at El. Gemmeiza Agric. Res. Station , A.R.C, Egypt, during the three successive seasons, 2009/2010, 2010/2011 and 2011/2012 to study genetic variance, gene action, heterosis, inbreeding depression, heritability and genetic advance for grain yield and its components and some agronomic characters. Six populations (P1, P2, F1, F2, Bc1 and Bc2) for three crosses were used in this study coming from (P1x P3), (P2 x P4) and (P3 x P4). Analysis of variance showed significant differences among the studied generations' means for all studied traits. Scaling test showed that most studied characters were significant indicating the presence of non-allelic interaction.. Additive type of gene effect was significant either positive or negative for no .of spikes / plant, 100-kernel weight and grain yield /plant in the first and second crosses. Meantime, dominance gene effects was significantly positive for all studied traits except plant height, no. of spikes /plant and grain yield /plant in the second cross .Additive x additive and additive x dominance type of gene actions were significantly positive or negative for all studied traits in the three crosses except for no .of spikes / plant in the first and second crosses and 100- kernel weight in the second and third crosses. On the other hand dominance x dominance type gene effect was found to be significant for all studied traits except plant height and 100-kernel weight in the first and third crosses, respectively. Heritability for days to heading in narrow sense was high and nearly equal to its corresponding in broad sense. High estimates for hertibility in broad sense were accompanied bymoderate value of narrow sense for no. of kernels /spike, 100 –kernel weight and grain yield plant in the three crosses.The third cross gave the highest heterotic effect towards earliness for number of days to heading and number of days to maturity with moderate heritability in narrow sense and with genetic advance being 1.59 and 1.98 days for both characters , respectively .Significant positive heterotic effects relative to better parent was obtained for no . of kernels / spike , 100 kernel weight and grain yield in the second and third crosses .

Heritability and gene effects for salinity tolerance in cucumber (Cucumis sativus L.) estimated by generation mean analysis

Cucumber production is greatly reduced by high salinity. Our recent identification of cucumber genotypes with relative tolerance to salinity provides the potential for development of salt tolerant cultivars if the mode of inheritance for this trait is known. In this study, two cucumber parental lines, 11411S (P1, salt tolerant), 11439S (P2, salt sensitive) were crossed to study gene actions responsible for inheritance of salinity tolerance (TOL), relative leaf number (RLN14), area of second largest fully expanded leaf (LA) and vine length (VL) under saline growing conditions. The six populations denoted as P1, P2, F1, B1 (F1×P1), B2 (F1×P2) and F2 (F1×F1) were subjected to 80mM NaCl stress in greenhouse pot experiments and data subjected to generation mean analysis. Epistatic gene effects on all the traits were not detected by A, B, C scaling test while joint scaling test showed the presence of non-allelic interactions for all the traits. TOL and RLN14 were predominantly under additive gene effect while inheritance LA was largely influenced by dominance and additive gene effects. Dominant gene effect significantly controlled the inheritance of VL. The narrow sense heritability for TOL, RLN14, VL and LA was 0.57, 0.26, 0.74 and 0.66, respectively. VL and LA registered significant positive heterobeltiosis. The presence of dominance gene effect and low heritability of photosynthesis enhancing trait, RLN14 makes it impractical to improve salinity through simple selection or pedigree breeding. Simultaneous selection for RLN14 and TOL in segregating population at advanced filial generations in this cross may be useful in developing cucumber varieties with increased salinity tolerance. Alternatively, intermating of superior segregants may be explored to concentrate the favorable genes for salt tolerance.

IMPROVING EGYPTIAN COTTON USING F2 TRIALLEL CROSSES

The aim of this investigation is to determine combining ability estimates for yield, yield components traits and some fiber properties in cotton. The genetic materials used in the present study included five cotton lines and their 30 F2 three-way crosses. All these lines belong to the species Gossypium barbadense L. In 2010 growing season, these genotypes were evaluated in a field trial experiment at Sakha Agricultural Research Station, Kafr El-Sheikh Governorate. The following traits were estimated: seed cotton yield/plant, lint yield/plant, boll weight, lint percentage, fiber strength, fiber fineness and upper half mean. The results showed that the performances of most the F2 three-way crosses were as good as or better than their both grand parents or/and their third parent. The mean squares of genotypes were highly significant for all studied traits. From the analyses of F2 triallel crosses, the parental lines Giza 86 (P1) and Suvin (P3) were the best combiners as a grand parent and/or parent for all studied traits except fiber fineness property. On the other hand, the variety Giza 89 (P5) was the best combiner as a grand parent for fiber fineness (F.F.) property. Therefore, these parental genotypes could be utilized in a breeding program to improve these traits through selection in the segregating generations. The results also investigated that the crosses (P1 x P3) x P4 , (P1 x P5) x P2, (P2 x P5) x P4, (P3 x P5) x P4 and (P3 x P4) x P2 would be the best for all studied yield traits and upper half mean (UHM) property. Meanwhile, (P1 x P2) x P4, (P1 x P5) x P4 and (P2 x P3) x P4 appeared to be the best promising crosses for breeding toward all studied yield traits potentiality. In addition, the combinations (P1 x P4) x P5 and (P3 x P4) x P5 appeared to be the best promising for all studied yield traits, fiber strength (F.S.) and upper half mean (UHM) properties.Furthermore, the combination (P2 xP4) x P1 appeared to be the best promising for seed cotton yield/plant (S.C.Y./P.), lint yield per plant (L.Y./P.) and fiber fineness (F.F.) property. Most of these combinations had involved at least one of the best general combiners for yield.This indicates that predications of superior crosses based on the general combining ability effects of the parents which would be generally valid and the contribution of non-allelic interaction in the inheritance of these traits.These findings may explain the superiority of the three-way crosses over their parental lines for these traits. Concerning epistatic variances, additive by additive genetic variances (s2AA), it showed positive values for all studied traits except for (F.F) property. While, additive by dominance genetic variances (s2AD) played the major role in controlling the inheritance of the studied characters of the triallel crosses. Therefore, recurrent selection might be useful in improving the studied characters of the triallel crosses in the breeding programs. The results also cleared that the calculated values of heritability in narrow sense ranged from 39.43% to 55.19% for seed cotton yield/plant (S.C.Y./P.) and fiber fineness (F.S.), respectively.

Genetic analysis for seed size in three crosses of chickpea (Cicer arietinumL.)

Sharma, S., Upadhyaya, H. D., Gowda, C. L. L., Kumar, S. and Singh, S. 2013. Genetic analysis for seed size in three crosses of chickpea (Cicer arietinum L.). Can. J. Plant Sci. 93: 387–395. Seed size (determined by 100-seed weight) is an important component of trade and yield in chickpea (Cicer arietinum L.). The present investigation was undertaken to study the possibility of maternal inheritance for seed size and to estimate relative importance of additive and non-additive gene effects on seed size in three chickpea crosses involving two desi (ICC 5002 and ICC 7672) and two kabuli (ICC 11255 and ICC 17109) genotypes. The study included parents, F1, F2, backcross generations, and their reciprocals. Differences in the reciprocal mean 100-seed weight of F1, F2, and backcross generations were not detected in any cross. No definite major gene segregation pattern was observed in the F2generation, and the continuous variation observed indicated quantitative inheritance. Generation mean analysis indicated the presence of additive gene effects controlling seed size in three crosses. Additive×additive type of non-allelic interactions were found significant in desi×kabuli crosses, ICC 5002×ICC 17109 and ICC 7672×ICC 11255. The selection and breeding procedure may be modified for maximum exploitation of the fixable additive×additive epistasis by delaying selection in later generations and by maintaining large populations prior to selection for maximum recombination of genes to occur.

Genetic Analysis of Sodicity Tolerance in Rice (Oryza SativaL.)

In order to estimate gene actions for sodicity tolerance, grain yield and its related traits in rice, six basic generations were evaluated in a randomized complete block design with three replications. Inheritance of salinity tolerance was determined in a cross between two rice cultivars, “ASD 18” (P1) a susceptible cultivar and “TRY” (R) 2 (P2) a tolerant one. The parents, F1, F2 and backcross generations were studied under sodic environment. The parents, F1, F2 and backcross generations were studied under sodicity conditions (Exchangeable Sodium Percentage 23). The data on 10 physio-morphological traits viz., days to 50 per cent flowering, plant height, number of productive tillers per plant, panicle length, spikelet fertility percentage, single plant yield, Na+: K+ ratio, proline content, chlorophyll a/b ratio and chlorophyll stability index were recorded. Generation means analysis of the data revealed that all these traits exhibit significant non-allelic interactions and suggest that complex epistatic interactions are more important in controlling sodicity tolerance traits. The simple additive dominance model was adequate to explain the inheritance of chlorophyll stability index. Due to the presence of greater non-additive gene effects, selection for almost all of the studied traits in this cross, especially in early generations, would be complex in conventional methods. Regarding the existence of additive and non-additive effects in controlling traits in this cross, inter se mattings followed by pedigree method of breeding might prove useful in improving sodicity tolerance in rice.

Genetic Analysis of Carotenoids Content in Red Pepper (Capsicum annuum L.) Fruit using Complete Diallel Cross

Regarding carotenoids content, the genetic basis, heritability and combining ability in six red pepper inbred lines were investigated using full diallel crosses. Both additive and non-additive gene actions govern inheritance of carotenoids content. The mean square of array through variance and covariance analysis (Wr-Vr) was insignificant, which suggest that inbred lines involved in diallel cross may have no epistatic effects. The Vr/Wr graph revealed the influence of partial dominant gene action towards low carotenoids content and the absence of non-allelic interaction. The H2 component was smaller than the H1 and the [H2/4H1] component was 0.187 less than 0.25, indicating unequal proportion of positive and negative alleles in the parents. The estimates of broad and narrow sense heritability for carotenoids content were 0.956 and 0.832, respectively. The variance of general combining ability (GCA) was relatively higher than that of specific combining ability (SCA), which implied that the additive gene effects were predominant as compared to both dominant and epistatic effects for the accumulation of carotenoids in this genetic population. The values of GCA of ``62024L1`` and ``62067L2`` were higher than those of the other parents. These 2 inbred lines, therefore, can be considered as useful breeding materials to enhance fruit carotenoids content in other red pepper varieties.