Inbreeding Depression For Yield Research Articles

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 ofbiparental 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.

Heterosis and inbreeding depression for yield and oil traits of sunflower genotypes under water stress conditions

The mean squares from analysis indicated significant differences was observed between treatments, inbred parents, F1 hybrids and F2 progenies for agronomic, oil and protein traits. The noteworthy variances between parents vs. hybrids indicated the importance of heterosis breeding. heterotic effects were found as potential hybrids for earliness, seed yield, oil and protein content in both the environments. The hybrids such as Thatta × UC-666, Mehran × Peshawar-93 and HO.1 × B-2 which have articulated high hybrid vigor in F1s for majority of the traits in normal and adverse conditions may be recommended for further commercial exploitation. The F2 progenies manifested high inbreeding depression for phenological traits and plant height signified that earlier maturing and dwarf plants resistant to lodging can achieved from filial generations.

English

English

Heterosis and inbreeding depression for yield and its components traits in barley (Hordeum vulgare)

Heterosis and inbreeding depression was analysed using a set of diallel crosses involving 10 diverse parents (excluding reciprocals). Heterosis over standard parent for grain yield per plant ranged from -9.65–45.45 (%) and -14.78–12.05 (%) under normal and late sown conditions, respectively and heterosis over better-parent for grain yield per plant ranged from -26.43–70.77(%) and -32.16–12.05(%) respectively. Nature and magnitude of heterosis and inbreeding depression varied across crosses, characters as well as environments. Considering the very high degree of heterosis in desirable direction, the importance of non-additive components of genetic variance was observed for yield and most of the yield contributing components. Cross II (K 603 × Azad) and cross IV (RD 2618 × PL 708) revealed better specific cross combinations to be used for heterosis. The study revealed good scope for commercial exploitation of heterosis as well as isolation of pure lines among the progenies of heterotic F1 for improvement of yield levels in barley.

Heterosis and inbreeding depression studies in pumpkin (Cucurbita moschata Duch. ex Poir.)

The investigation was carried out in pumpkin (Cucurbita moschata Duch. ex. Poir.) to study the heterosis and inbreeding depression for yield and yield contributing characters in three possible crosses (Odisha local x Pusa Viswas, Rajasthan local x Pusa Viswas and Ambili x Pusa Viswas) involving four parents (Odisha local, Rajasthan local, Ambili and Pusa Viswas) with four generations (P1, P2, F1and F2) in randomized block design with four replications. Relative heterosis and heterobeltiosis was found to be significant and negative for days to open first female flower, number of node at which first female flower appeared, vine length, fruit weight, fruit polar diameter, fruit equatorial diameter and sex ratio. Positive relative heterosis was observed for number of fruits per vine for most of the crosses. Hence heterosis breeding can be exploited for production of more number of fruits per vine. Significant positive heterobeltiosis was also observed for days to first female flower appearance, fruit weight, fruit equatorial diameter, fruit yield per vine and fruit yield per plot in cross II Rajathan local x Pusa Viswas. The significant inbreeding depression for all the yield characters except number of fruits per vine was observed.

Studies on heterosis and inbreeding depression for yield and its attributes in greengram [<italic>Vigna radiata</italic> (L.) Wilczek

Five crosses were evaluated to study the extent of heterosis and inbreeding depression for yield and its attributing traits in greengram. Heterosis over mid parent, better parent and standard variety was significant for pods/plant and seed yield/plant. The crosses exhibiting high heterosis also expressed high inbreeding depression for pods/plant, pods/cluster and seed yield/plant. Heterosis coupled with inbreeding depression revealed the predominance of non-additive gene action for most of the characters studied. Owing to its autogamous genetic architecture and biological constrains of the crop the heterosis could be exploited only by isolating the desirable segregants for yield attributes adopting bi-parental or recurrent selection in early segregating generations followed by single plant selection in subsequent generations.

Segregation pattern and inbreeding depression in F2 generation of some hybrid okra varieties

An experiment was conducted in randomized complete block design (RCBD) with three replications in the experimental field of Regional Horticulture Research Station (RHRS), Bangladesh Agriculture Research Institute (BARI), Lebukhali, Patuakhali during April, 2014 to October, 2014 for assessing the inbreeding depression, genetic parameters, gene action and segregation pattern of Okra [Abelmoschusesculentus (L.) Moench]. The experiment was comprised of five commercial hybrid Okra genotypes such as Tara sonali, Bimala, Juboraj, Suvo 1and Noor, their respective F2 progenies along with a check variety named as BARI Dherosh 1. Results of the experiment indicated that there were considerable variability among the F1 and their F2. The yield were in-between 14.81 to 7.92 Kg plot-1in case of F1 generation, which deteriorate to 10.32 to 5.32 Kg plot-1 in F2 generation. Broad sense heritability computed through variance component method showed that all the quantitative traits were moderate to highly heritable. The trait yield per plot exhibited 68.83% broad sense heritability coupled with 50.96% genetic advance suggesting the existence of sufficient amount of genetic variability for improvement of this trait and also indicates that the trait is more amenable to selection and could be improved easily. In case of segregation pattern, plant height and pod pubescence content exhibit as polygenic trait. Leaf shape, fruit base shape and branching pattern showed complete dominance and fruit color displayed incomplete dominance. The present investigation thus provide information about the nature and magnitude of genetic variation, segregation pattern and inbreeding depression for yield and its components in okra so as to formulate suitable breeding strategy and isolate potential parents and promising crosses for further breeding program.Asian J. Med. Biol. Res. June 2015, 1(2): 316-335

Genetic architecture, heterosis and inbreeding depression for yield and yield associated physiological traits in rice (Oryza sativa L.) under drought condition

Simple and joint scaling tests led to similar inferences in respect of presence or absence of epistasis in majority of cases across the fourteen characters of six crosses in two conditions. The generation mean analysis revealed importance of additive (d) and/or dominance (h) gene effects as well as one or more of the epistatic gene interactions (i, j, l) for all the seven characters in most of the crosses under both the conditions. However, nature and magnitude of gene effects and epistatic interactions for a character exhibited considerable variation across the six crosses and two environmental conditions. Significance of dominance gene effects and epistatic interactions for most of the traits in six crosses under two conditions indicated that exploitation of heterosis through hybrid varieties appears to be a potential alternative. Only in drought condition, considerable number of crosses exhibited positive and significant estimates of standard heterosis across seven characters. Present study indicated apparent lack of desirable heterosis of requisite degree. It appears that extremely diverse nature of parents involved in six cross combinations may have resulted in incompatible gene combinations or genetic architecture in crosses resulting into poor performance and lack of heterosis for most of the characters. The positive and significant heterobeltiosis was noted for relative water content and membrane thermo stability in cross VI in irrigated condition.SAARC J. Agri., 13(1): 50-62 (2015)

Hybrid Vigour and Inbreeding Depression for Yield and its Component Traits in Bitter Gourd (Momordica charantia L.)

Twenty eight crosses generated using eight genotypes viz., IC-033227, IC-044417, IC-044438, IC-045339, IC-085622, IC-470550, IC-470558 and IC-470560 were evaluated to study the extent of heterosis and inbreeding depression for yield and yield attributing characters in bitter gourd at College of Horticulture, Rajendranagar, Hyderabad. The experiment was laid out in a randomized block design with three replications. The results revealed that most of the crosses showed significant heterosis over mid parent and better parent for the traits studied. The maximum heterosis (over mid and better parents) for yield vine−1 was observed in IC-044438×IC-045339 (96.03 and 58.48%) followed by IC-044417×IC-470558 (60.24 and 54.01%), IC-045339×IC-470558 (54.09 and 38.70%) and IC-045339×IC-085622 (52.64 and 32.44%). Furthermore these crosses were found superior for one or more fruit characters like average fruit weight and fruit length (IC-044438×IC045339) and number of fruits vine−1 (IC-044417×IC-470558). The crosses showing significant heterosis for yield also revealed inbreeding depression thus indicated major involvement of non-additive gene action in the inheritance of yield vine−1. However for days to 1st female flower and node number at 1st female flower, significant heterosis in desired direction was observed in IC-045339×IC- 470550 (−9.57 and -7.65%) and IC-044438×IC-045339 (−20.34 and -15.14%) respectively had no inbreeding depression. These results suggesting that it would be useful to utilize these promising cross combinations which showed superior performance for earliness, fruit yield and other yield attributes for exploitation of heterosis. Hence, methods like heterosis breeding, recurrent selection and progeny selection may be employed for improvement in bitter gourd.

Studies on heterosis and inbreeding depression for yield and phsiological traits in groundnut (Arachis hypogaeal.)

Estimates of heterosis and inbreeding depression were obtained for 28 crosses. For pod yield per plant, the maximum better parent and mid parent heterosis was recorded in the cross TCGS-584× K-1375 closely followed by K-1375× TCGS-647 and ICGV-99029 x K-1375. Kernel yield per plant, the range of heterosis was observed-11.10% (TIR-25 x ICGV-91114) to 57.61% (K-1375 x TCGS-647), -14.18% (TIR-25 x ICGV-91114) to 55.85% (K-1375 x TCGS-647) and-21.57% (TCGS-584 x TCGS-647) to 23.09% (TPT-4 x TIR-25) over mid parent, better parent and standard parent respectively. For the important of moisture stress tolerant characters viz., for specific leaf area, highest negative heterosis was recorded by TCGS-584 x JL-220 over mid parent (−23.12%), better parent (−25.14%) and standard parent (−34.95%). For leaf area index, TCGS 584 x JL-220 (−22.36%) over mid parent, TIR-25 x JL-220 (−33.81%) over better parent and ICGV-99029 x K-1375 (−24.14%) over standard parent for transpiration rate, ICGV-91114 x ICGV-99029 over mid parent (−26.33%) and better parent (−32.21%) and TPT-4 x TIR-25 over standard parent (−15.06%) hybrid showed desired significant heterosis. It was evident that ICGV-91114 x TCGS-584 for SPAD chlorophyll meter reading, TIR-25 x TCGS-584 for photosynthetic rate, ICGV-91114 x ICGV-99209 for water use efficiency and TIR-25 x JL-220 for harvest index and as many as twenty two crosses for yield displayed higher levels of heterosis also had high inbreeding depression.

Mode of gene action, heterosis and inbreeding depression for yield and its components in tomato (Solanum lycopersicum L.)

The objectives of this study were to determine heterosis and the type of gene action controlling some economical traits of tomato. Six populations of the cross CastleRock×CLN 2498E (P1, P2, F1, F2, BC1 and BC2) were used to study the genetic parameters of tomato traits. Means of the six populations were widely differed for most of the studied traits. One or more of the three scaling tests (A, B and C) were significant for some studied traits indicating that additive dominance model was inadequate to know the role of the type of gene action in the inheritance of these traits. Additive gene effects were found to be important in the inheritance of average fruit weight. Dominance and dominance×dominance gene effects were important in the inheritance of plant height, number of branches per plant fruit firmness and early yield. Heterosis relative to better parent was present for number of branches per plant, early yield, total yield and fruit firmness. The heritability estimates in broad sense were high for early yield, total yield, average fruit weight, fruit firmness and TSS content. However, heritability estimates in narrow sense were high for early yield and average fruit weight and moderate for TSS content. The estimated potence ratio (P) was larger than one for all studied traits except for average fruit weight and TSS content.

Heterosis studies for yield and its components in bread wheat over environments

A set of diallel crosses involving 10 parents was made to have information on the extent of heterosis over mid-parent and better parent and inbreeding depression for yield and yield contributing characters under three different environments. Marked heterobeltiosis for grain yield and its important components were observed. For grain yield, 83 crosses showed significant positive heterobeltiosis in all the three sowing dates, however, twenty crosses showed significant consistent heterobeltiosis for grain yield per plant over all the three environments. The maximum heterobeltiosis for grain yield per plant observed was 50.94% (Raj 3765 x HD 2285), 121.08% (PBW 373 x HD 2329) and 93.96% (PBW 373 x HD 2329) under early, normal and late sowing conditions, respectively. Cross PBW 373 x HD 2329 in both early and normal plantings and cross Raj 3765 x HD 2285 under late planting were observed most heterotic for grain yield. The crosses showing heterosis for grain yield were not heterotic for all the characters. Heterosis for grain yield per spike followed by tillers per plant and 1000-grain weight was independently associated with heterosis for grain yield in early and normal plantings. However, heterosis for grain yield per spike, dwarf plant height and tillers per plant contributed maximum towards yield heterosis. Significant inbreeding depression was recorded frequently for yield and yield contributing traits, however, in a few traits it was observed significant negative indicated that F(2) was superior to F(1) considered desirable combination for trait(s). The study reveals good scope for commercial exploitation of heterosis as well as isolation of pure lines among the progenies of heterotic F(1) for improvement of yield levels in bread wheat.

Little heterosis for yield and yield components in hybrids of six cucumber inbreds

Heterosis and inbreeding depression for fruit yield has been reported for pickling cucumber (Cucumis sativus L.). However, cucumber inbreds often perform as well as hybrids, and there is little inbreeding depression. The objectives of this study were to reexamine the amount of heterosis and inbreeding depression for fruit yield and yield components in pickling cucumber, and to determine the relationship between yield components and yield for heterosis. Two pickling cucumber inbreds (M 12, M 20) and inbreds from four open-pollinated monoecious cultivars (‘Addis’, ‘Clinton’, ‘Wisconsin SMR 18’, ‘Tiny Dill’) were hybridized to form four F1 hybrids (‘Addis’ × M 20, ‘Addis’ × ‘Wis. SMR 18’, ‘Clinton’ × M 12, M 20 × ‘Tiny Dill’). F1 hybrids were then self-pollinated or backcrossed to generate F2, BC1A, and BC1B progeny. Thirty plants of each generation within each hybrid family were grown in plots 3.1 m long with four replications in each of two seasons. Data were collected from once-over harvest for vegetative, reproductive, yield, and fruit quality traits. Heterosis and inbreeding depression for fruit yield and yield components were not observed in three of the hybrids. Only ‘Addis’ × ‘Wis. SMR 18’ exhibited high-parent heterosis and inbreeding depression for total, marketable, and early fruit weight. For ‘Addis’ × ‘Wis. SMR 18’, heterosis for fruit yield was associated with a decreased correlation between percentage of fruit set and fruit weight, an increased negative correlation between percentage of fruit set and both the number of branches per plant and the percentage of pistillate nodes, and an increased negative correlation between the number of nodes per branch and total fruit weight. Inbreeding depression was associated with a weakening of the strong negative correlations between percentage of fruit set and the number of branches per plant, and between the number of nodes per branch and total fruit weight. Those correlations were associated with high-parent heterosis and inbreeding depression only for one cross, and do not necessarily apply to future crosses in which heterosis may be observed for yield. We did not observe the heterosis or inbreeding depression for yield in cucumber in most of the crosses as was reported by Ghaderi & Lower (1979a; 1979c).

Heterosis and Inbreeding Depression for Yield of Pickling Cucumber (Cucumis sativus L.) Hybrids

Currently, both hybrid and inbred pickling cucumber cultivars are being grown commercially in the United States. Heterosis for yield in pickling cucumber has been previously reported. However, heterosis has not been repeatable in other studies. The objective of this study was to determine the existence of heterosis and inbreeding depression for yield in pickling cucumber. Six pickling cucumber inbreds (`Addis', `Clinton', M 12, M 20, `Tiny Dill', `Wisconsin SMR 18') were hybridized to form four F1 hybrid families (`Addis × M 20, `Addis' × `Wis. SMR 18', `Clinton' × M 12, M 20 × `Tiny Dill'). Within each family, F2, BC1A and BC1B generations were also formed. Thirty plants of each generation within each family were grown in 3.1-m plots for four replications in the spring and summer seasons of 1996 at the Horticultural Crops Research Station in Clinton, N.C. Data were collected at once-over harvest for total, marketable, and early yield in terms of number (1000 fruit/ha) and weight (Mg/ha). In addition to yield, a fruit shape rating was collected for each plot. High parent heterosis for yield (total and marketable fruit weight) was only observed for `Addis' × `SMR 18' grown in the summer season. The three other families did not exhibit heterosis for total, marketable, and early yield. Heterosis for shape rating was not observed for any family. `Addis' × `Wis. SMR 18' also exhibited inbreeding depression for total fruit weight, marketable fruit weight, early fruit number, and early fruit weight during the spring season and for marketable fruit number and marketable fruit weight during the summer season.

Genetic Improvement for Yield and Fertility of Alfalfa Cultivars Representing Different Eras of Breeding

Alfalfa (Medicago sativa L.) exhibits inbreeding depression for forage yield and also tends to set fewer seeds following self‐pollination than following cross‐pollination. The objectives of this study were to estimate changes in yield potential, inbreeding depression for yield, and self‐ and cross‐fertilities of alfalfa cultivars adapted to Wisconsin and representing different eras of breeding from 1898 to 1985. In addition, two University of Wisconsin‐Madison experimental cultivars with well‐known breeding histories were included in the study. The S0 and S1 populations derived from each cultivar were evaluated for 3 yr for forage yield. Self‐ and cross‐fertilities of some S0 populations were measured in a greenhouse study. Both S0 and S1 populations of modern (Era 3) cultivars yielded greater than those of the oldest (Era 1) cultivars. Era 3 S0 populations generally yielded more than those of cultivars released in the 1940s and 1950s (Era 2) but this was not true for S1 populations. These results suggest that favorable alleles have accumulated in modern alfalfa cultivars but that this mostly occurred between Eras 1 and 2. Inbreeding depression decreased between Eras 1 and 2 and increased between Eras 2 and 3. Increased heterozygosity or exploitation of nonadditive genetic effects may account for much of the improvement in cultivar yield potential that occurred between Eras 2 and 3. Era 3 cultivars had a significantly lower ratio of self‐fertility to cross‐fertility than Era 1 cultivars. Therefore, modern cultivars appear to have improved capacity to produce high proportions of cross‐pollinated seed when nonself pollen is available, compared with older cultivars.

Selection‐Induced Differences among Strains of Iowa Stiff Stalks Synthetic Maize1

Different recurrent selection methods have been used for the improvement of traits in maize (Zea mays L.). The relative performance of nine strains of Iowa Stiff Stalk Synthetic (BSSSCO) derived different methods of recurrent selection for different traits were determined by evaluating strains per se, diallel crosses among strains, and Sl generations of strains and strain crosses. Objectives were to determine selection. induced differences among the nine strains and the direct and indirect effects of selection for yield, grain moisture, root and stalk lodging, and dropped ears. Replicated field trials were conducted in six environments. BS13(S)C2 had the highest yield per se (7.83 Mg ha‐1) and the highest yielding $1 generation (5.82 Mg ha‐1). Inbreeding depression for yield was less for the highly selected strains and for crosses involving those strains. Selection for resistance to European corn borer (Ostrinia nubilalis Hübner) did not significantly affect yield, but selection for resistance to corn rootworm (Diabrotica virgifera Le Conte) did have a significant negative correlated effect on grain yield. Changes in frequency of additive effects due to selection for yield improvement were more important for BSI3(S)C2 (seven cycles half‐sib and two cycles S2 selection) than for BSSS(R)C8 (eight cycles reciprocal recurrent selection). Greater changes were observed in frequency of alleles with dominance effects in BSSS(R)C8 than in BS13(S)C2. After removal the effects of drift, rate of realized gain per cycle was 0.279 Mg ha‐1 (4.4%) for BS13(S)C2 and 0.259 Mg ha‐1 (4.1%) for BSSS(R)C8. Yield of the 36 strain crosses ranged from 6.10 Mg ha‐1 for BSSSCO ✕ BSSS(RW)C2 to 9.37 Mg ha‐1 for BSSS(R)C8 ✕ BS13(S)C2. Average midparent heterosis for yield was 11.7%. Yield differences among strains and level of heterosis expressed in crosses suggested selection‐induced genetic diversity among strains of BSSSCO.

Heterosis and Inbreeding Depression for Yield in Populations Derived from Six Crosses of Cucumber1

Abstract Six crosses were made among eight cultivars and breeding lines of cucumber (Cucumis sativus L.). Within each cross 11 populations (including parents) representing 5 levels of heterozygosis were studied. Data were collected on fruit weight/plot, fruit number/plot, average fruit weight and fruit bearing index. Regression analysis was used to partition differences associated with levels of heterozygosis into linear, quadratic, and lack of fit components. With the exception of one cross, heterozygosis had significant positive effects on all characters. Linear responses of all populations to heterozygosis were highly significant for all characters in 5 of the 6 crosses. Incidences of significant quadratic and lack of fit mean squares were low. For all traits, with the exception of some instances of interallelic interactions, a genetic model based on cumulative action of independent loci with partial dominance explains differences associated with levels of heterozygosis.