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1.
The importance of fast-trackt generation advancement in developing superior germplasm has been recognized in breeding of many crop species. To address this issue in tomato, immature seeds were excised from fruit at different maturity stages and transferred to culture medium. The best culture medium was modified full strength Moorashige–Skoog (MS) salts supplemented with 0.1 mg l−1 IAA, 0.5 mg l−1 IBA, 0.5 mg l−1 GA3 and 2% sucrose. If the excised seeds were able to grow, most showed shoot formation after a week. Seeds extracted as early as 10 days after pollination were successfully cultured provided they were transferred aseptically and without injury. No morphological or physiological changes in regenerated plants and their fruit relative to the parent were detected. Germination from immature seeds of tomato is a simpler alternative to in vitro culture of immature embryos or callus, as it can be undertaken in comparatively less stringent laboratory conditions. Using this approach, five generations can be produced in a year in contrast to a maximum of three generations with conventional methods. This offers an opportunity for rapid generation advancement aimed towards population development when coupled with marker assisted selection in tomato breeding for biotic and abiotic stress tolerance.  相似文献   

2.
Micronutrient malnutrition, especially selenium (Se), iron (Fe), and zinc (Zn) deficiency, is a major global health problem. Previous attempts to prevent micronutrient malnutrition through food fortification, supplementation, and enrichment of staple crops has had limited success. Canadian grown lentils are rich in micronutrients Fe (73–90 mg kg−1), Zn (44–54 mg kg−1), Se (425–673 μg kg−1), and have very low concentrations of phytic acid (2.5–4.4 mg g−1). Our preliminary studies using a Caco-2 cell model show that the uptake of Fe from lentils is relatively greater than that of most other staple food crops. Moreover, preliminary results from our human nutrition study in Sri Lanka show an increased trend in blood Se concentration after lentil consumption. This article briefly overviews our previously published results as well as data from international lentil field trials, and describes the potential for biofortified lentil to provide a whole food solution to combat global human micronutrient malnutrition.  相似文献   

3.
The presence of high levels of sinigrin in the seeds represents a serious constraint for the commercial utilisation of Ethiopian mustard (Brassica carinata A. Braun) meal. The objective of this research was the introgression of genes for low glucosinolate content from B. juncea into B. carinata. BC1F1 seed from crosses between double zero B. juncea line Heera and B. carinata line N2-142 was produced. Simultaneous selection for B. carinata phenotype and low glucosinolate content was conducted from BC1F2 to BC1F4 plant generations. Forty-three BC1F4 derived lines were selected and subject to a detailed phenotypic and molecular evaluation to identify lines with low glucosinolate content and genetic proximity to B. carinata. Sixteen phenotypic traits and 80 SSR markers were used. Eight BC1F4 derived lines were very close to N2-142 both at the phenotypic and molecular level. Three of them, with average glucosinolate contents from 52 to 61 micromoles g−1, compared to 35 micromoles g−1 for Heera and 86 micromoles g−1 for N2-142, were selected and evaluated in two additional environments, resulting in average glucosinolate contents from 43 to 56 micromoles g−1, compared to 29 micromoles g−1 for Heera and 84 micromoles g−1 for N2-142. The best line (BCH-1773), with a glucosinolate profile made up of sinigrin (>95%) and a chromosome number of 2n = 34, was further evaluated in two environments (field and pots in open-air conditions). Average glucosinolate contents over the four environments included in this research were 42, 31 and 74 micromoles g−1 for BCH-1773, Heera and N2-142, respectively. These are the lowest stable levels of glucosinolates reported so far in B. carinata.  相似文献   

4.
With the objective of selecting superior recombinant lines of snap bean, four segregating F2 populations were selected by early generation testing and advanced by single seed descent. In a randomized complete block design with two replications within sets 120 F6:7 lines were obtained and evaluated for seven traits of agronomic interest. The mean pod yield of the F6:7 generation was 72% higher than in generation F2, confirming the efficiency of early selection. There was genetic variability in the F6:7 lines within the sets. The selection of superior genotypes was possible by the high estimates of narrow-sense heritability. Highest gains in simultaneous selection of traits were expressed by the indices proposed by Mulamba & Mock for the genetic standard deviation and by Williams, based on tentatively attributed arbitrary weights. Line 3 of the F6:7 generation, with a yield of 8,050.0000 kg ha−1 and pod fiber content of 0.3650% is highly promising to be release as new cultivar.  相似文献   

5.
An additive-dominance, additive × additive (ADAA) and genotype × environment interaction mix model was used to study the genetic control of β-carotene and l-ascorbic acid in six basic generations (P1, P2, F1, F2, BC1P1 and BC1P2) of tomato derived from the cross CDP8779 accession (Solanum lycopersicum L.) × CDP4777 accession (S. lycopersicum var. cerasiforme). The study was performed in two environments: (1) open field; (2) protected environment, consisting of hydroponic cultivation in a glasshouse. The results indicate that β-carotene accumulation was mainly additive (32.2% of the genetic component), with a small dominant component (4.2%) and an important additive × environment interaction contribution (63.6%). In target environments with moderate to high temperatures and no limiting radiation, this the expression additive × environment interaction could substantially enhance the β-carotene content. This trait showed also a high narrow-sense heritability (h 2 = 0.62). Ascorbic acid accumulation was also mainly additive (61.7% of the genetic component), with a minor additive epistatic component (21.5%). This epistatic effect caused a negative heterosis that reduced the positive main additive effect. Nevertheless, in the described target environments, the additive × environment interaction contribution (16.8%) may enhance the ascorbic acid content and compensate for the negative heterosis effect. The total narrow-sense heritability of this trait can be considered useful (h 2 = 0.52). In conclusion, the CDP4777 accession is a very interesting donor parent for the joint improvement of β-carotene (without diminishing lycopene content) and ascorbic acid content in commercial nutraceutical tomato breeding programmes; the F1 hybrids derived from this accession showed nearly 450% of the commonly reported average β-carotene content and close to 130% of the ascorbic acid content of the female parent.  相似文献   

6.
Selection of winter wheat cultivars with long coleoptiles is an important component of improving emergence, weed suppression and grain yield in low rainfall regions of the world. Seven winter wheat cultivars were hybridized in a Griffing’s half-diallel mating design, method 2 (reciprocals excluded, parents included), model 1 (fixed), and the progeny analyzed for coleoptile length in the F1 through F4 for response to selection, general combining ability (GCA), specific combining ability (SCA) and heritability. Highly significant differences existed for GCA among progeny in each generation. SCA was highly significant in the F1, F2 and F4, although SCA estimates were inconsistent among generations in each progeny population. The SCA/GCA ratio was 0.15, 0.11, 0.06 and 0.04 in the F1 through the F4, respectively, indicating that additive effects increased with homozygosity. Broad-sense heritability for coleoptile length was estimated at 0.86, 0.76, 0.60 and 0.78 for the F1 through the F4, respectively. Realized heritabilities ranged from −0.16 to 0.85 with a mean of 0.32 in the F3 and ranged from −0.68 to 0.68 with a mean of 0.13 in the F4. Spearman’s rank correlation coefficients (RS) were significant for all generation comparisons except the F1:F2, indicating that changes in rank for coleoptile length were insignificant. Cultivars with long coleoptiles and high GCA were the best parents for improving coleoptile length. Sustained selection over generations for coleoptile length was more effective than one generation of selection for genotypes both with and without reduced height genes.  相似文献   

7.
Fusarium root rot (FRR) is a major disease of common bean worldwide. Knowledge of the inheritance of resistance to FRR would be important in devising strategies to breed resistant varieties. Therefore, a 12 × 12 full diallel mating scheme with reciprocal crosses was performed to generate 132 F1 progenies, which were then advanced to the F3. The progenies were evaluated for resistance to FRR under green house conditions in Uganda. General combining ability (GCA) effects were highly significant (P ≤ 0.01) for disease scores. Specific combining ability effects were not significant (P > 0.05) in the F1, but were highly significant (P < 0.01) in the F3 generation. These results indicate that resistance to FRR was governed by genes with additive effects in combination with genes with non-additive effects. Reciprocal differences were also significant (P = 0.01) at F1 and F3, primarily reflecting a large influence of maternal effects in both these generations. In fact, susceptible parents did not differ significantly (P > 0.05) for disease scores when used as paternal parents in the F3, but differed strongly as maternal parents (P = 0.0002). Generally, the progenies were distinctly more resistant when the resistant parent was used as the female in crosses, especially as observed in the F3. The maternal effects were strong in the F3 generation, suggesting a complex form of cytoplasmic–genetic interaction. The non-maternal reciprocal effects in the F3 were significant (P < 0.05) in both the resistant × resistant diallel, and in the resistant × susceptible crosses. Mid-parent heterosis (MPH) occurred in most crosses, with average heterosis approximately equal in each of the three generations, indicating that epistasis was probably more influential than dominance of individual genes. Gene-number formulas indicated that several genes were involved in resistant × susceptible crosses. Among resistant × resistant crosses, many produced continuous distributions of F1 progeny scores, suggesting polygenic inheritance, while bi-modal distributions were characteristic of the F3 distributions, and fit expected ratios for two or three loci segregating in each cross. Dominant forms of epistasis favoring resistance were strongly indicated. Parent–offspring heritability estimates were moderate. Overall, the results indicate that resistant parents contain a number of different resistance genes that can be combined with the expectation of producing strong and durable resistance. The lines MLB-49-89A, MLB-48-89, RWR719 and Vuninkingi, with large and negative GCA effects, contributed high levels of resistance in crosses and would be recommended for use in breeding programs.  相似文献   

8.
The nutritional value of cucumber (Cucumis sativus L.) can be improved by the introgression of β-carotene (i.e., provitamin A and/or orange flesh) genes from “Xishuangbanna gourd” (XIS; Cucumis sativus var. xishuangbannanesis Qi et Yuan) into US pickling cucumber. However, the genetics of β-carotene content has not been clearly defined in this US market type. Thus, three previous populations derived from a US pickling cucumber (‘Addis’) × XIS mating were evaluated for β-carotene content, from which the high β-carotene inbred line (S4), ‘EOM 402-10’, was developed. A cross was then made between the US pickling cucumber inbred line ‘Gy7’ [gynoecious, no β-carotene, white flesh; P1] and ‘EOM 402-10’ [monoecious, possessing β-carotene, orange flesh; P2] to determine the inheritance of β-carotene in fruit mesocarp and endocarp tissue. Parents and derived cross-progenies (F1, F2, BC1P1, and BC1P2) were evaluated for β-carotene content in a greenhouse in Madison, Wisconsin. While F1 and BC1P1 progeny produced mature fruits possessing white, light-green, and green (0.01–0.02 μg g−1 β-carotene) mesocarp, the F2 and BC1P2 progeny mesocarp segregated in various hues of white, green, yellow (0.01–0.34 μg g−1 β-carotene), and orange (1.90–2.72 μg g−1 β-carotene). Mesocarp and endocarp F2 segregation adequately fit a 15:1 [low-β-carotene (0.01–0.34 μg g−1): high-β-carotene (1.90–2.72 μg g−1)] and 3:1 (low-β-carotene: high-β-carotene) ratio, respectively. Likewise, segregation of carotene concentration in mesocarp and endocarp tissues in BC1P2 progeny adequately fit a 3:1 (low-β-carotene: high-β-carotene) and 1:1 (low-β-carotene: high-β-carotene) ratio, respectively. Progeny segregations indicate that two recessive genes control the β-carotene content in the mesocarp, while one recessive gene controls β-carotene content in the endocarp. Single marker analysis of F2 progeny using the carotenoid biosynthesis gene Phytoene synthase determined that there was no association between this gene and the observed β-carotene variation in either fruit mesocarp or endocarp.  相似文献   

9.
Investigations on concentration of mineral elements including Fe and Zn in wheat grains are important for human health. Two hundreds and sixty-five cultivars and advanced lines were collected and sown at Anyang experimental station of the Institute of Crop Science of the Chinese Academy of Agriculture Sciences in season 2005–2006 to evaluate the genetic variation of major mineral element concentrations in wheat grain. Twenty-four selected cultivars were also planted at seven representative locations in seasons 2005–2006 and 2006–2007 to evaluate the effects of genotype, environment, and genotype by environment interaction on mineral element concentrations. The 265 genotypes displayed a large variation for all mineral elements investigated including Fe and Zn, ranging from 28.0 to 65.4 mg kg−1 and 21.4 to 58.2 mg kg−1 for Fe and Zn, with mean values of 39.2 and 32.3 mg kg−1, respectively. Jimai 26, Henong 326, and Jingdong 8 displayed high Fe and Zn concentrations, and Jimai 26 and Henong 326 also displayed high concentrations of Cu, Mg, K, P, and protein content. Jingdong 8 is the most promising leading cultivar for increasing Fe and Zn concentrations. All mineral element concentrations including Fe and Zn were largely influenced by environment effects. Production of high Fe concentration can be best secured at Jiaozuo and Jinan, and high Zn concentration can be best secured at Jinan and Xuzhou, since samples from these locations in the two seasons are characterized by high Fe or Zn concentration, compared with the other locations. High and significant genotype by environment interaction effects on all mineral element concentrations were also observed, with ratios of genotype by environment to genotype variances all larger than 1.20. Grain Fe concentration was highly significant and positively correlated with that of Zn, indicating a high possibility to combine high Fe and Zn traits in wheat breeding. It also indicated strong positive correlations between concentrations of Fe, Zn, and protein content.  相似文献   

10.
K. Reinink  R. Groenwold 《Euphytica》1987,36(3):733-744
Summary The inheritance of nitrate content in lettuce was analysed using 16 F2 populations and three F3 populations. Frequency distributions of nitrate content in F2 and F3 populations were unimodal and symmetrical, indicating a quantitative inheritance. Both significant positive and negative deviations of the F2 mean from the mid-parent value were found, indicating dominance or epistasis. Deviations towards low nitrate content were more frequent than deviations in the other direction. Estimates of heritabilities for nitrate content in the F2 populations ranged from 18% to 69% and were in most cases above 50%. Crosses between low nitrate cultivars did not have lower estimates of heritability in the F2 than crosses between cultivars with larger differences in nitrate content. In one case a genotype x experiment interaction for nitrate content of parental cultivars was found.Three F3 populations of crosses between cultivars with low nitrate content were analysed. Estimates of heritabilities for F3 line means ranged from 78% to 91% and estimates of the genetic standard deviation of nitrate content in unselected advanced generations ranged from 0.24–0.33 g kg–1. The estimates of heritabilities and of genetic variation in advanced generations offer good prospects of selection of low nitrate genotypes in lettuce. A comparison of efficiency of selection in the F2 generation and F3 line selection is made.  相似文献   

11.
Genetic parameters relating isoflavone and protein content in soybean seeds   总被引：3，自引：0，他引：3  
Isoflavones are a class of compounds present in high amounts in soybean seeds, which can be used for prevention and treatment of several chronic diseases. Proteins present in soybean seeds are the basis for the high nutritional value and versatility of this leguminous species in animal and human feeding. The main goals of this work were to estimate heritabilities for isoflavone contents in soybean seeds and the correlation between isoflavone and protein contents. Commercial variety IAC-100 (high isoflavone and normal protein contents) and the line BARC-8 (low isoflavone and high protein contents) were crossed, and one single F1 plant derived 97 F2 seeds, which were used to obtain F3 seeds. A sample of F3 seeds from each F2 plant was used for isoflavone determination by HPLC and protein by the Kjeldahl method. Six isoflavone forms were detected: daidzin, genistin, glycitin, malonyldaidzin, malonylgenistin and malonylglycitin. Total isoflavone contents ranged from 427.92 to 965.89 μg per gram of dry seed and the protein content ranged from 45.17 to 34.95% in BARC-8 and IAC-100, respectively. Our results indicate that it is possible to select for high isoflavone content in early breeding generations because the broad sense heritabilities for the contents of the various isoflavone forms were higher than 90%. In addition, high correlation values among the contents of the individual isoflavone forms were observed (between 0.80 and 0.98). However, negative correlation values were obtained between isoflavone and protein contents, ranging from −0.51 to −0.37 for the different isoflavone forms. The correlation value of −0.47 between total isoflavone and protein contents confirmed the negative correlation between these two parameters, as reported by other authors. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

12.
Summary Seed size as determined by seed weight, is an important trait for trade and component of yield and adaptation in chickpea (Cicer arietinum L.). Inheritance of seed size in chickpea was studied in a cross between ICC11255, a normal seed size parent (average 120 mg seed−1) and ICC 5002, a small seed size parent (average 50 mg seed−1). Seed weight observations on individual plants of parents, F1, F2, and backcross generations, along with reciprocal cross generations revealed that the normal seed size was dominant over small seed size. No maternal effect was detected for seed size. The numbers of individuals with normal, small and medium (average 150 mg seed−1) seed sizes in F 2 population were 1237, 323 and 111 fitting well to the expected ratio of 12:3:1 (χ2 = 0.923, P = 0.630). The segregation data of backcross generations also indicated that seed size in chickpea was controlled by two genes with dominance epistasis. We designate the genotype of ICC 11255 as Sd 1 Sd 1 sd 2 sd 2, and ICC 5002 as sd 1 sd 1Sd2 Sd 2 wherein Sd 1 is epistatic to Sd 2 and sd 2 alleles.  相似文献   

13.
A large industrial oil market has recently developed for high erucic acid (>500 g kg−1) rape (Brassica napus L.) cultivars. This research was conducted to: (i) determine genetic effects for five fatty acids, (ii) determine if maternal effects influence fatty acid content of progeny, and (iii) estimate correlations among fatty acid contents in hybrid progeny. Lines with very high erucic acid content and very low erucic acid content were used to develop eight generations to estimate additive, dominance, and epistatic effects for fatty acid content using Generation Means Analyses. Mean oleic, linoleic, linolenic, eicosenoic and erucic acid content differed among generations and additive genetic effects were important for control of all five fatty acids, contributing from 84% to 97% of the total sums of squares for each fatty acid. Epistasis was observed in the inheritance of eicosenoic acid. Maternal effects were not detected.  相似文献   

14.
Combining ability for some important physiological parameters in sesame were examined to understand the nature of gene action and to identify parents for breeding programme. Seven diverse genotypes of sesame, their 21 F1s and 21 F2s were grown in summer, 2003, in a randomized complete block design with three replications. Data were collected on leaf area index (LAI) at 30, 45, 60 and 75 days after sowing (DAS), crop growth rate (CGR) estimated between 30–45 DAS, 45–60 DAS and 60–75 DAS, days to peak flowering (DPF), duration of flowering (DF), duration from peak flowering to maturity (DFM), oil content in percentage (OC) and oil yield (OY) plant−1. Analysis of combining ability was done on the above physiological characters following Method-2, Model-I of Griffing (Aust J Biol Sci 9:463–493 1956). Variances due to general combining ability (GCA) and specific combining ability (SCA) for all the physiological traits were highly significant in both F1 and F2 generations indicating importance of both additive and non-additive gene actions for the inheritance of all the physiological characters in both F1 and F2 generations. Preponderance of non-additive gene action was recorded for CGRs, LAI 3, LAI 4, DPF, DF and OY in both the F1 and the F2 generations. For OC additive gene action was predominant in F1 while non-additive gene action in F2. The genotype OS-Sel-2 appeared as best overall general combiner in both the F1 and the F2 generations. For DPF, DF and DFM, the variety B 67 was best general combiner, followed by CST 2002, which could be utilized for developing early flowering and early maturing lines with determinate growth habit. Association between GCA-effects and mean performance of the parents suggested that the performance per se could be a good indicator of its ability to transmit the desirable attributes to its progenies. Crosses CST 2002 × TKG 22, CST 2002 × MT 34, MT 34 × AAUDT 9304-14-4, AAUDT 9304-14-4 × B 67, TKG 22 × Rama and TKG 22 × B 67 which showed high SCA-effect for OY, also exhibited positive and significant SCA-effects for other physiological component characters in F1 generation. The overall results indicated that crosses CST 2002 × TKG 22 and MT 34 × AAUDT 9304-14-4 could be utilized for development of high oil yielding hybrids. The crosses OS-Sel-2 × AAUDT 9304-14-4, AAUDT 9304-14-4 × B 67 and MT 34 × OS-Sel-2 could be promising for isolation of superior recombinants for high oil yield coupled with early maturity and other growth characters in advanced generations of segregation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

15.
The use of resistant cultivars is one of the best methods for nematode control and reduction of economic losses caused by these pathogens. Studies of inheritance of nematode resistance in common bean (Phaseolus vulgaris L.) are nonetheless scarce. The present paper reports on the estimation of genetic parameters associated with resistance to the root nematode Meloidogyne incognita race 1 in common beans. Two contrasting bean lines, ‘Aporé’ (P1 = nematode resistant) e ‘Macarr?o Rasteiro Conquista’ (P2 = susceptible), and the generations F1 (P1 × P2), F2 (P1 × P2), BC1(P1) = (F1 × P1) and BC1(P2) = (F1 × P2), were assessed 45 days after nematode inoculation, through a scale related to the number of eggs per gram of root tissue. Dominant genetic effects were inferior in magnitude to additive effects, indicating incomplete dominance of nematode resistance. Dominance was in the direction of increased nematode resistance (i.e., lower number of eggs per g root). Resistance to Meloidogyne incognita race 1 in common bean is under control of a single gene locus, with incomplete dominance of the resistance allele present in ‘Aporé’, but modifier genes affecting its expression appear to be present in the susceptible parent ‘Macarr?o Rasteiro Conquista’.  相似文献   

16.
The fungal disease cercospora leaf spot CLS (Cercospora zonata) has affected major faba bean (Vicia faba) production regions in southern Australian in the last several years. This study offers the first report of sources of resistance to CLS in faba bean and describes techniques to evaluate resistance to C. zonata in faba bean genotypes within a controlled environment. The method was rapid (43 days), repeatable (R 2 > 0.74) and demonstrated positive correlations (R 2 > 0.45–0.80) to data collected from field disease nurseries under naturally established CLS epiphytotics. All faba bean cultivars currently adopted by the Australian industry were found to be susceptible to CLS and defoliation was found to be an important component of disease expression. Genetic analysis of segregation patterns in F 2 derived F 3 families of 1322/2*Farah (resistant*susceptible) showed the mode of inheritance of resistance to C. zonata was monogenic dominant. F 3 families were shown to segregate in the ratio of 1:2:1 for homozygous resistant: heterozygous: homozygous susceptible (χ22 = 2.78; P > 0.05) and individual plants within heterozygous F 3 families segregated in the ratio of 3:1 for resistant: susceptible responses (χ12 = 2.93; P > 0.05). Monogenic dominant inheritance also explained the change in frequency of resistant and susceptible plants within a population of cv. Cairo following one generation of self-pollination (χ2 = 0.88, 0.3 < P < 0.5). The sources of resistance identified in this study are being used to transfer CLS resistance to adapted faba bean genotypes for future cultivar releases to the southern Australian industry.  相似文献   

17.
Increasing productivity through improvement of photosynthesis in faba bean breeding programmes requires understanding of the genetic control of photosynthesis‐related traits. Hence, we investigated the gene action of leaf area, gas exchange traits, canopy temperature, chlorophyll content, chlorophyll fluorescence parameters and biomass. We chose inbred lines derived from cultivars 'Aurora' (Sweden) and 'Mélodie' (France) along with an Andean accession, ILB 938, crossed them (Aurora/2 × Mélodie/2, ILB 938/2 × Aurora/2 and Mélodie/2 × ILB 938/2), and prepared the six standard generations for quantitative analysis (P1, P2, F1, F2, B1, and B2). Gene action was complex for each trait, involving additive and dominance gene actions and interactions. Additive gene action was important for SPAD, photosynthetic rate, stomatal conductance and Fv/Fm. Dominance effect was important for biomass production. It is suggested that breeders selecting for productivity can maximize genetic gain by selecting early generations for canopy temperature, SPAD and Fv/Fm, then later generations for biomass. The information on genetics of various contributing traits of photosynthesis will assist plant breeders in choosing an appropriate breeding strategy for enhancing productivity in faba bean.  相似文献   

18.
Hot pepper is the most important worldwide grown and consumed spice and vegetable crop. Though hybrid breeding has been proposed for genetic improvement in the crop, but there is lack of information on heterosis in crosses among crop genotypes in Ethiopia. Twelve genotypes (nine Asian and three Ethiopian parents) of hot pepper were crossed in 2003 cropping season in a half-diallel fashion to fit Griffing’s fixed effect model analysis. An open field experiment was conducted in 2004/2005 to investigate heterosis for fourteen traits in 66 F1 hybrids grown together with their 12 selfed parents. Highly significant genotypic differences were observed for all the traits except for leaf area. Variance component due to specific combining ability (dominance) were larger than that due to general combining ability (additive) for each of the studied traits with few exceptions. Broad sense heritability (H b2) for fruit traits were more than 60% and with wide gap from narrow sense heritability (h n2) for most of the important traits like number of fruit per plant (H b2 = 88.3% and h n2 = 46.0%), days to maturity (H b2 = 87.2% and h n2 = 23.1%) and dry fruit yield per plant (H b2 = 72.6% and h n2 = 14.6%). Maximum heterosis over mid-parent and better-parent, and economic superiority of hybrid over standard check were recorded, respectively for dry fruit yield per plant (163.8, 161.8 and 92.1%), number of fruits per plant (104.4, 79.6 and 136.4%) and days to maturity (−29.8, −31.5 and −23.6%). These observations suggested a possibility of utilizing dominance genetic potentiality available in diverse genotypes of the crop by heterosis breeding for improving hot pepper to the extent of better economic return compared to the current commercial cultivar under production in the country. Low narrow sense versus very high broad sense heritability for days to maturity and dry fruit yield per plant could be a sign for achievability of earliness and high fruit yield using heterosis in hot pepper. The maximum heterobeltiosis were recorded either from F1s obtained from Ethiopian and Asian crosses or from within Asian crosses, suggesting the possibility of maximizing heterosis by considering genetically diverse parental genotypes. The manifestation of highest heterosis in hybrids from among Asian lines indicated existence of genetic diversity among Asian genotypes and the potentiality for improvement of hot pepper using genotypes from different regions of the world along with elite inbred lines from local cultivars.  相似文献   

19.
Genetic variance, heritability, and expected response from selection arc useful in devising alternative methods and criteria of: selection. The objectives of this study were to estimate these for seed yield and its components from 200 F2: populations involving 80 cultivars and lines of mostly small-seeded dry bush bean (Phaseolus vulgaris L.) of habits growth I, II, and III of Middle-American origin. All cultivars and lines were crossed in eight sets of ten parents each in a Design II mating system. The F2 populations, without parents, were evaluated in the field in a replicates-in-sets design at two locations in Colombia in 1983. Estimates of additive genetic variance were significant for yield, pods/m2, seeds/pod, and seed weight. Interaction with environments was also significant. Values for nonadditive genetic variance were not significant for either yield or yield components. The estimates of narrow sense heritability, based on the F2 population mean and unbiased by genotype x environment interaction, were 0.21 ± 0.13 for yield. 20 ± 0.13 for pods/m2, 0.57 ± 0.13 for seeds/pod, and 0.74 ± 0.15 for seed weight. The expected direct response from selection of the top 20 % of F2 populations for yield per se would result in a 4.30 % increase in yield with a correlated response of 0.21 % in seed weight. In contrast, the expected gain from direct selection for seed weight would result in a 11.76 % increase in seed weight with a, correlated gain of 0.28 % for yield. Direct selection for pods/m2 would decrease yield, seeds/pod and seed weight, while direct selection for seeds/pod would reduce pods/m2 and seed weight but increase seed yield by 0.37 %. Data on yield from replicated trials in the early segregating generations could be utilized for identification and selection of promising crosses and families or lines with crosses for dry bean yield improvement.  相似文献   

20.
Genetic variability, correlation, path coefficient analysis and test of normality was conducted in an F8 recombinant inbred aerobic rice population developed by single seed descent method to evaluate its potential as a mapping population. Estimates of genotypic variance, phenotypic variance, genotypic coefficient of variance (GCV), phenotypic coefficient of variance (PCV), heritability in the broad sense (H) and expected genetic advance at 5% selection index (GA) for grain yield and other attributing characters were computed. In all the cases, PCV was higher than GCV indicating the influence of environment on the characters. High heritability coupled with high GA was observed for several plant traits; number of tillers, plant height, total number of spikelets panicle−1, biomass plant−1, straw weight, harvest index and grain yield plant−1 and hence offered good scope for selection. Grain yield plant−1 was found to be positively correlated with plant height, number of tillers, panicle length, panicle exsertion, number of panicles plant−1, single panicle weight, test weight, number of fertile spikelets panicle−1, straw weight, biomass plant−1, harvest index and grain breadth both at genotypic and phenotypic levels. Harvest index exerted maximum positive direct effect, followed by biomass plant−1 and straw weight on grain yield plant−1 at phenotypic level. Shapiro-Wilks “W test of normality” indicated that the population was skewed towards female parent IR50 for some traits and for some others towards Moroberekan, the male parent. Most of the characters that showed skewness were platykurtic with a kurtosis value of less than 3.  相似文献   

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