Nine inbred lines of rapeseed （Brassica napus L.） used as male were crossed to five recessive genetic male sterile （RGMS） lines used as female to produce 45 single crosses. The crosses, their parents and a check h...Nine inbred lines of rapeseed （Brassica napus L.） used as male were crossed to five recessive genetic male sterile （RGMS） lines used as female to produce 45 single crosses. The crosses, their parents and a check hybrid were tested at two locations during 2007 to 2008 for testing the performance and heterosis of hybrids for seed yield and other characters. Results showed that variations for seed yield, oil content, days to flowering and days to maturity were significant. Mean squares for hybrids were significant for all characters. High heterosis （-4.5%-88.3%）, heterobeltiosis （-15.6%-81.1%） and standard heterosis G34.8%-33.1%） were found for the seed yield. The highest heterosis and heterobeltiosis were found in the cross QH303-4A× 1190. The highest standard heterosis was found in the cross Qianyou8A×Q034. Both positive and negative heterosis of single crosses were detected for the oil content. Small heterosis was found for days to flowering and days to maturity. Among parents, Ⅲ 188, Ⅲ224, and Q034 were proved to be the superior for seed yield when used as parents in most of the hybrid combinations. 2365, Ⅲ224, and QH303-4AB were good for high oil content breeding, Ⅲ 176, 2313 and Qianyou3AB were good for the early hybrid breeding. Total 11 hybrids yielded higher than 2 500 kg·hm^-2 and also gave significantly positive heterosis, heterobeltiosis and standard heterosis. Among them, 10 crosses gave higher oil content than that of check. These crosses can be used in the future breeding program for the seed yield and the oil content. Two crosses including Qianyou3A × Ⅲ224 and Qianyou3A×2313 can be used for the early breeding program.展开更多
Historically,re-selection,pedigree,and mass selection breeding methods have been used to develop open-pollinated cultivars of Upland cotton(Gossypium hirsutum L.). Due to the
Background High temperature stress at peak flowering stage of cotton is a major hindrance for crop potential.This study aimed to increase genetic divergence regarding heat tolerance in newly developed cultivars and hy...Background High temperature stress at peak flowering stage of cotton is a major hindrance for crop potential.This study aimed to increase genetic divergence regarding heat tolerance in newly developed cultivars and hybrids.Fifty cotton genotypes and 40 F1(hybrids)were tested under field conditions following the treatments,viz.,high temperature stress and control at peak flowering stage in August and October under April and June sowing,respectively.Results The mean squares revealed significant differences among genotypes,treatments,genotype×treatment for relative cell injury,chlorophyll contents,canopy temperature,boll retention and seed cotton yield per plant.The genetic diversity among 50 genotypes was analyzed through cluster analysis and heat susceptibility index(HSI).The heat tolerant genotypes including FH-Noor,NIAB-545,FH-466,FH-Lalazar,FH-458,NIAB-878,IR-NIBGE-8,Weal-AGShahkar,and heat sensitive,i.e.,CIM-602,Silky-3,FH-326,SLH-12 and FH-442 were hybridized in line×tester fashion to produce F1 populations.The breeding materials’populations(40 F1)revealed higher specific combining ability variances along with dominance variances,decided the non-additive type gene action for all the traits.The best general combining ability effects for most of the traits were displayed by the lines,i.e.,FH-Lalazar,NIAB-878 along with testers FH-326 and Silky-3.Specific combining ability effects and better-parent heterosis were showed by the crosses,viz.,FH-Lalazar×Silky-3,FH-Lalazar×FH-326,NIAB-878×Silky-3,and NIAB-878×FH-326 for seed cotton yield and yield contributing traits under high temperature stress.Conclusion Heterosis breeding should be carried out in the presence of non-additive type gene action for all the studied traits.The best combiner parents with better-parent heterosis may be used in crossing program to develop high yielding cultivars,and hybrids for high temperature stress tolerance.展开更多
Background:The utilization of heterosis has greatly improved the productivity of cotton worldwide.However,a major constraint for the large-scale promotion of F_(1) hybrid cotton is artificial emasculation and pollinat...Background:The utilization of heterosis has greatly improved the productivity of cotton worldwide.However,a major constraint for the large-scale promotion of F_(1) hybrid cotton is artificial emasculation and pollination.This study proposed the potential utilization of F_(2) hybrids to improve upland cotton production through a comparative evaluation of hybrid generations.Results:Eight upland cotton varieties were analyzed and crosses were made according to NCII incomplete diallel cross-breeding design in two cotton belts of China.Variance analysis revealed significant differences in agronomic,yield,and fiber quality in both generations and environments.The broad-sense heritability of agronomic and yield traits was relatively higher than quality traits.Furthermore,the narrow-sense heritability of some traits was higher in F_(2) than in the F_(1) generation in both cotton belts.Overall,parental lines Zhong901,ZB,L28,and Z98 were observed with maximum combining ability while combinations with strong special combining ability were ZB×DT,L28×Z98,and ZB×851.The yield traits heterosis was predominant in both generations.However,the level of heterosis was altered with trait,hybrid combination,generation,and environment.Interestingly,L28×Z98 performed outstandingly in Anyang.Its lint yield(LY)was 24.2%higher in F_(1) and 11.6%in F_(2) than that of the control Ruiza 816.The performance of SJ48×Z98 was excellent in Aral which showed 36.5%higher LY in F_(2)and 10.9%in F_(2)than control CCRI 49.Further results revealed most hybrid combinations had shown a low level of heterosis for agronomic and fiber quality traits in both generations.Comparatively,ZB×DT and L28×Z98 showed hybrid vigor for multiple traits in both generations and cotton belts.It is feasible to screen strong heterosis hybrid combinations with fine fiber in early generations.In the two environments,the correlation of some traits showed the same trend,and the correlation degree of Anyang site was higher than that of Aral site,and the correlation of some traits showed the opposite trend.According to the performance of strong heterosis hybrid combinations in different environments,the plant type,yield and fiber traits associated with them can be improved according to the correlation.Conclusions:Through comparative analysis of variance,combining ability,and heterosis in F_(2)and F_(2)hybrids in different cotton belts,this study proposed the potential utilization of F_(2)hybrids to improve upland cotton productivity in China.展开更多
Background:Climate change and particularly global warming has emerged as an alarming threat to the crop productivity of field crops and exerted drastic effects on the cropping patterns.Production of cotton has been dr...Background:Climate change and particularly global warming has emerged as an alarming threat to the crop productivity of field crops and exerted drastic effects on the cropping patterns.Production of cotton has been dropped down to one million bales from 1.4 million bales since 2015 in Pakistan due to the increase in temperature at critical growth stages,i.e.,flowering and boll formation.Keeping in view the importance of cotton in the country,this study was conducted to investigate the genetic effects conferring heat tolerance in six populations(P1,P2,F1,F2,BC1 and BC2)developed from cross-1 and cross-2,i.e.,VH-282×FH-142 and DNH-40×VH-259.Results:The results revealed that cross-1 performed better in heat stress as compared with cross-2 for majority of the traits recorded.Boll weight and ginning outturn(GO-T)were highly effected under heat stress and had negative correlation with Relative cell injury(RCI).Boll weight,fiber length,fiber strength and fiber fineness were under the control of non-additive gene action,whereas RCI was controlled by additive gene effects.Lower values of genetic advance coupled with higher values of broad sense heritability for these traits except RCI confirmed the role of non-additive genetic effects.Duplicate types of epistasis were recorded for fiber strength in cross-1 in normal condition.However,complementary type of non-allelic interaction was recorded for fiber strength under normal condition,fiber fineness and RCI under heat stressed condition in cross-1.Likewise,boll weight,GOT and fiber length in populations derived from cross-2 in normal condition were also under the influence of complementary type of non-allelic interaction.Significant differences among values of mid parent and better parent heterosis for boll weight in both normal and heat stress condition provided the opportunity to cotton breeders for utilization of this germplasm for improvement of this trait through exploitation of heterosis breeding.Conclusion:Cross-1 performed better in heat stress and could be utilized for development of heat tolerant cultivar.RCI was under the influence of additive gene action,so one can rely on this trait for screening of large number of accessions of cotton for heat stress.While other traits were predominantly controlled by non-additive gene action and selection based on these should be delayed in later generations.展开更多
The perforated stiffened panel is generally found as a sub-component of sophisticated structures.The fundamental purpose of this panel is to withstand against buckling under complicated loading and environmental condi...The perforated stiffened panel is generally found as a sub-component of sophisticated structures.The fundamental purpose of this panel is to withstand against buckling under complicated loading and environmental conditions.Hence,an accurate knowledge of critical buckling behaviour of stiffened panels is very much essential for a reliable and lightweight structural design.In this paper,the focus is on quasi-laminated panels with different cutout shapes of various sizes and their responses to hygrothermal environments under nonlinearly varying edge loads and is compared with the locally stiffened panels.Towards this,the modelling of the panel and stiffener is done by adopting nine-noded heterosis plate elements and three noded beam elements respectively.The stiffener formulation is suitably modified in order to take the torsional effect also into consideration along with the effect of shear deformation.Initially,the plate and the stiffener elements are treated separately,and then the displacement compatibility is maintained between them by using the transformation matrix.For a given loading and geometric discontinuity,the stress distribution within the perforated panel is highly non-uniform in nature and hence a dynamic approach has been used to calculate buckling loads by adopting two sets of boundary conditions,one set for pre-buckling stress analysis and the second set for buckling analysis.Four different quasi-isotropic stacking sequences are deliberated in this work by varying different ply-orientation in each scheme.The study also addresses the effect of various parameters such as nonlinear loads,hygro-thermal loads,cutout size and shapes,position of cutout,stiffener parameters,stacking sequences,thickness of plate and boundary conditions.展开更多
The concept and research achievements of the heterotic group and model in corn were introduced briefly. The results showed that the domestic corn germplasm could be divided into three main heterotic groups and two mai...The concept and research achievements of the heterotic group and model in corn were introduced briefly. The results showed that the domestic corn germplasm could be divided into three main heterotic groups and two main heterotic models. The research on corn germplasm in Heilongjiang Province could be concluded as three main heterotic groups and three main heterotic models. Some new opinions about corn heterotic group and heterotic model in Heilongjiang Province were proposed such as Northeast group and NortheastxLancaster model.展开更多
On the Datong Yak Breeding Farm of Qinghai Province(Datong farm), the scientists of the Lanzhou Institute of Animal Science and Veterinary Pharmaceutics of Chinese Academy of Agricultural Sciences, in collaboration wi...On the Datong Yak Breeding Farm of Qinghai Province(Datong farm), the scientists of the Lanzhou Institute of Animal Science and Veterinary Pharmaceutics of Chinese Academy of Agricultural Sciences, in collaboration with others,explored the possibility to cross wild yak bulls with domestic yak cows in the past 20years and a new yak breed, the Datong yak, has been developed.展开更多
Diploid hybrid derived from dihaploid Neo-tuberosum × Solanum phurejaand progeny of the diploid hybrid backcrossed to dihaploid Neo-tuberosum,which could produce 2n pollen, were crossed as male to S.tuberosumssp....Diploid hybrid derived from dihaploid Neo-tuberosum × Solanum phurejaand progeny of the diploid hybrid backcrossed to dihaploid Neo-tuberosum,which could produce 2n pollen, were crossed as male to S.tuberosumssp. tubersumc.v. NEA303. The performance of the 4x hybrids obtained from 4x × 2x cross was investigated for yield and yield components in the first year clonal generation. The 4x hybrids shown a drastic heterosis in plant height. Marketable yield/plant for the 4x hybrid was no better than that for the 4x cultivar, but the best hybrid individual of the two hybrid populations exceeded the best individual of the cultivar by 260 g/plant and 60 g/plant, respectively. Total yield/plant for the 4x hybrids performed drastic heterosis, however tuber number/plant was high and mean tuber weight low. These limit the use of 4x × 2x hybrids in potato breeding programs and need to be improved in near future.展开更多
Progenies derived from crosses between Solarium tuberosum and 2n pollen-Producing diploid hybrids, exhibit obvious hybrid vigor. The 2n pollen-producing clone can act as a bridge in crossing S. tuberosum and S. andige...Progenies derived from crosses between Solarium tuberosum and 2n pollen-Producing diploid hybrids, exhibit obvious hybrid vigor. The 2n pollen-producing clone can act as a bridge in crossing S. tuberosum and S. andigena with S. phureja. Populations from 4x-2x crosses show more unifomity and less segregation compared with that of 4x-4x crosses.The parent-offspring correlation for the traits, starch content and tuber number, is significant at 0.01 level. The regrssion equations are Y (mp-F1)=1.0 + 1.2x and Y (mp - F1) = 5.3 + 0.8x, respectively. The 2n pollen-producing clones play an impotant role in increasing tuber stach content.Estimates of the combining ability for the main yield components indicate that additive effect prodominatcs for such trais as plot yield, tuber weight per plant and starch content, whereas both additive and non-additive effects lay equal stress on mean tuber weight and non-additive effect is important for tuber number. In general, non-additive effect appears to be important in the progenies of 4x-2x crosses.Tuber number shows apparent heterosis while mean tuber weight dos not. Thus, it is necessary for 2n pollen-producing clones to be selected for high mean tuber weight and low tuber number before their use in commercial potato production.In the double cropping region of Anhui, the 4x - 2x hybrids seem to be more adaptive than S. tuberosum x S. andigena hybrids, but the yield of 4x - 2x cross is lower than that of the cross S. tuberosum x S. andigena in Harbin region.In Harbin region, the better combination type is in the from of S. andigena x (phureja-haploid Group tuberosum), and the best cross is also in the from. In Anhui, the better combination type is S. tuberosum x (phureja - haploid Group tuberosum), and the best cross is that using a variety of S. tuberosum as its parent. The progeny tubers of 4x - 2x cross have a short dormant period and are suitable for the double cropping region.展开更多
Neo-tuberosum derived from S. tuberosum ssp. andigena is a very important genetic resource in potato breeding. In 1970′s, Neo-tuberosum clones were introduced into China and improving programs were started at that ti...Neo-tuberosum derived from S. tuberosum ssp. andigena is a very important genetic resource in potato breeding. In 1970′s, Neo-tuberosum clones were introduced into China and improving programs were started at that time. The improved clones of it were obtained through recurrent selection in different latitudes of China. According to obvious heterosis appeared in crossing with common potato varieties, Neo-tuberosum would be good parents for breeding and true potato seed (TPS) production. Dihaploid of Neo-tuberosum were obtained by parthenogenesis, and its male fertility was recovered by crossing with S. phureja as male parents. Using acceptable improved Neo-tuberosum clones as a parent, the tuber yield of TPS population was increased greatly.展开更多
基金Supported by the 11th Five Year Plan of Rapessed Program in Guizhou Province, Scientific Contract of Guizhou N2 No.(2005) 3006-02-03
文摘Nine inbred lines of rapeseed （Brassica napus L.） used as male were crossed to five recessive genetic male sterile （RGMS） lines used as female to produce 45 single crosses. The crosses, their parents and a check hybrid were tested at two locations during 2007 to 2008 for testing the performance and heterosis of hybrids for seed yield and other characters. Results showed that variations for seed yield, oil content, days to flowering and days to maturity were significant. Mean squares for hybrids were significant for all characters. High heterosis （-4.5%-88.3%）, heterobeltiosis （-15.6%-81.1%） and standard heterosis G34.8%-33.1%） were found for the seed yield. The highest heterosis and heterobeltiosis were found in the cross QH303-4A× 1190. The highest standard heterosis was found in the cross Qianyou8A×Q034. Both positive and negative heterosis of single crosses were detected for the oil content. Small heterosis was found for days to flowering and days to maturity. Among parents, Ⅲ 188, Ⅲ224, and Q034 were proved to be the superior for seed yield when used as parents in most of the hybrid combinations. 2365, Ⅲ224, and QH303-4AB were good for high oil content breeding, Ⅲ 176, 2313 and Qianyou3AB were good for the early hybrid breeding. Total 11 hybrids yielded higher than 2 500 kg·hm^-2 and also gave significantly positive heterosis, heterobeltiosis and standard heterosis. Among them, 10 crosses gave higher oil content than that of check. These crosses can be used in the future breeding program for the seed yield and the oil content. Two crosses including Qianyou3A × Ⅲ224 and Qianyou3A×2313 can be used for the early breeding program.
文摘Historically,re-selection,pedigree,and mass selection breeding methods have been used to develop open-pollinated cultivars of Upland cotton(Gossypium hirsutum L.). Due to the
基金Higher Education Commission of Pakistan for funding the experiments
文摘Background High temperature stress at peak flowering stage of cotton is a major hindrance for crop potential.This study aimed to increase genetic divergence regarding heat tolerance in newly developed cultivars and hybrids.Fifty cotton genotypes and 40 F1(hybrids)were tested under field conditions following the treatments,viz.,high temperature stress and control at peak flowering stage in August and October under April and June sowing,respectively.Results The mean squares revealed significant differences among genotypes,treatments,genotype×treatment for relative cell injury,chlorophyll contents,canopy temperature,boll retention and seed cotton yield per plant.The genetic diversity among 50 genotypes was analyzed through cluster analysis and heat susceptibility index(HSI).The heat tolerant genotypes including FH-Noor,NIAB-545,FH-466,FH-Lalazar,FH-458,NIAB-878,IR-NIBGE-8,Weal-AGShahkar,and heat sensitive,i.e.,CIM-602,Silky-3,FH-326,SLH-12 and FH-442 were hybridized in line×tester fashion to produce F1 populations.The breeding materials’populations(40 F1)revealed higher specific combining ability variances along with dominance variances,decided the non-additive type gene action for all the traits.The best general combining ability effects for most of the traits were displayed by the lines,i.e.,FH-Lalazar,NIAB-878 along with testers FH-326 and Silky-3.Specific combining ability effects and better-parent heterosis were showed by the crosses,viz.,FH-Lalazar×Silky-3,FH-Lalazar×FH-326,NIAB-878×Silky-3,and NIAB-878×FH-326 for seed cotton yield and yield contributing traits under high temperature stress.Conclusion Heterosis breeding should be carried out in the presence of non-additive type gene action for all the studied traits.The best combiner parents with better-parent heterosis may be used in crossing program to develop high yielding cultivars,and hybrids for high temperature stress tolerance.
基金sponsored by funds from the Zhongyuan Academician Foundation (212101510001)the Fundamental Research Funds for State Key Laboratory of Cotton Biology (CB2021C08)the General Program of the National Natural Science Foundation of China (31871679)
文摘Background:The utilization of heterosis has greatly improved the productivity of cotton worldwide.However,a major constraint for the large-scale promotion of F_(1) hybrid cotton is artificial emasculation and pollination.This study proposed the potential utilization of F_(2) hybrids to improve upland cotton production through a comparative evaluation of hybrid generations.Results:Eight upland cotton varieties were analyzed and crosses were made according to NCII incomplete diallel cross-breeding design in two cotton belts of China.Variance analysis revealed significant differences in agronomic,yield,and fiber quality in both generations and environments.The broad-sense heritability of agronomic and yield traits was relatively higher than quality traits.Furthermore,the narrow-sense heritability of some traits was higher in F_(2) than in the F_(1) generation in both cotton belts.Overall,parental lines Zhong901,ZB,L28,and Z98 were observed with maximum combining ability while combinations with strong special combining ability were ZB×DT,L28×Z98,and ZB×851.The yield traits heterosis was predominant in both generations.However,the level of heterosis was altered with trait,hybrid combination,generation,and environment.Interestingly,L28×Z98 performed outstandingly in Anyang.Its lint yield(LY)was 24.2%higher in F_(1) and 11.6%in F_(2) than that of the control Ruiza 816.The performance of SJ48×Z98 was excellent in Aral which showed 36.5%higher LY in F_(2)and 10.9%in F_(2)than control CCRI 49.Further results revealed most hybrid combinations had shown a low level of heterosis for agronomic and fiber quality traits in both generations.Comparatively,ZB×DT and L28×Z98 showed hybrid vigor for multiple traits in both generations and cotton belts.It is feasible to screen strong heterosis hybrid combinations with fine fiber in early generations.In the two environments,the correlation of some traits showed the same trend,and the correlation degree of Anyang site was higher than that of Aral site,and the correlation of some traits showed the opposite trend.According to the performance of strong heterosis hybrid combinations in different environments,the plant type,yield and fiber traits associated with them can be improved according to the correlation.Conclusions:Through comparative analysis of variance,combining ability,and heterosis in F_(2)and F_(2)hybrids in different cotton belts,this study proposed the potential utilization of F_(2)hybrids to improve upland cotton productivity in China.
基金funding for this research was provided by Higher Education Commission,Pakistan
文摘Background:Climate change and particularly global warming has emerged as an alarming threat to the crop productivity of field crops and exerted drastic effects on the cropping patterns.Production of cotton has been dropped down to one million bales from 1.4 million bales since 2015 in Pakistan due to the increase in temperature at critical growth stages,i.e.,flowering and boll formation.Keeping in view the importance of cotton in the country,this study was conducted to investigate the genetic effects conferring heat tolerance in six populations(P1,P2,F1,F2,BC1 and BC2)developed from cross-1 and cross-2,i.e.,VH-282×FH-142 and DNH-40×VH-259.Results:The results revealed that cross-1 performed better in heat stress as compared with cross-2 for majority of the traits recorded.Boll weight and ginning outturn(GO-T)were highly effected under heat stress and had negative correlation with Relative cell injury(RCI).Boll weight,fiber length,fiber strength and fiber fineness were under the control of non-additive gene action,whereas RCI was controlled by additive gene effects.Lower values of genetic advance coupled with higher values of broad sense heritability for these traits except RCI confirmed the role of non-additive genetic effects.Duplicate types of epistasis were recorded for fiber strength in cross-1 in normal condition.However,complementary type of non-allelic interaction was recorded for fiber strength under normal condition,fiber fineness and RCI under heat stressed condition in cross-1.Likewise,boll weight,GOT and fiber length in populations derived from cross-2 in normal condition were also under the influence of complementary type of non-allelic interaction.Significant differences among values of mid parent and better parent heterosis for boll weight in both normal and heat stress condition provided the opportunity to cotton breeders for utilization of this germplasm for improvement of this trait through exploitation of heterosis breeding.Conclusion:Cross-1 performed better in heat stress and could be utilized for development of heat tolerant cultivar.RCI was under the influence of additive gene action,so one can rely on this trait for screening of large number of accessions of cotton for heat stress.While other traits were predominantly controlled by non-additive gene action and selection based on these should be delayed in later generations.
文摘The perforated stiffened panel is generally found as a sub-component of sophisticated structures.The fundamental purpose of this panel is to withstand against buckling under complicated loading and environmental conditions.Hence,an accurate knowledge of critical buckling behaviour of stiffened panels is very much essential for a reliable and lightweight structural design.In this paper,the focus is on quasi-laminated panels with different cutout shapes of various sizes and their responses to hygrothermal environments under nonlinearly varying edge loads and is compared with the locally stiffened panels.Towards this,the modelling of the panel and stiffener is done by adopting nine-noded heterosis plate elements and three noded beam elements respectively.The stiffener formulation is suitably modified in order to take the torsional effect also into consideration along with the effect of shear deformation.Initially,the plate and the stiffener elements are treated separately,and then the displacement compatibility is maintained between them by using the transformation matrix.For a given loading and geometric discontinuity,the stress distribution within the perforated panel is highly non-uniform in nature and hence a dynamic approach has been used to calculate buckling loads by adopting two sets of boundary conditions,one set for pre-buckling stress analysis and the second set for buckling analysis.Four different quasi-isotropic stacking sequences are deliberated in this work by varying different ply-orientation in each scheme.The study also addresses the effect of various parameters such as nonlinear loads,hygro-thermal loads,cutout size and shapes,position of cutout,stiffener parameters,stacking sequences,thickness of plate and boundary conditions.
基金Supported by Scientific and Technology Project of Heilongjiang Province (GA06B102-2)
文摘The concept and research achievements of the heterotic group and model in corn were introduced briefly. The results showed that the domestic corn germplasm could be divided into three main heterotic groups and two main heterotic models. The research on corn germplasm in Heilongjiang Province could be concluded as three main heterotic groups and three main heterotic models. Some new opinions about corn heterotic group and heterotic model in Heilongjiang Province were proposed such as Northeast group and NortheastxLancaster model.
文摘On the Datong Yak Breeding Farm of Qinghai Province(Datong farm), the scientists of the Lanzhou Institute of Animal Science and Veterinary Pharmaceutics of Chinese Academy of Agricultural Sciences, in collaboration with others,explored the possibility to cross wild yak bulls with domestic yak cows in the past 20years and a new yak breed, the Datong yak, has been developed.
文摘Diploid hybrid derived from dihaploid Neo-tuberosum × Solanum phurejaand progeny of the diploid hybrid backcrossed to dihaploid Neo-tuberosum,which could produce 2n pollen, were crossed as male to S.tuberosumssp. tubersumc.v. NEA303. The performance of the 4x hybrids obtained from 4x × 2x cross was investigated for yield and yield components in the first year clonal generation. The 4x hybrids shown a drastic heterosis in plant height. Marketable yield/plant for the 4x hybrid was no better than that for the 4x cultivar, but the best hybrid individual of the two hybrid populations exceeded the best individual of the cultivar by 260 g/plant and 60 g/plant, respectively. Total yield/plant for the 4x hybrids performed drastic heterosis, however tuber number/plant was high and mean tuber weight low. These limit the use of 4x × 2x hybrids in potato breeding programs and need to be improved in near future.
文摘Progenies derived from crosses between Solarium tuberosum and 2n pollen-Producing diploid hybrids, exhibit obvious hybrid vigor. The 2n pollen-producing clone can act as a bridge in crossing S. tuberosum and S. andigena with S. phureja. Populations from 4x-2x crosses show more unifomity and less segregation compared with that of 4x-4x crosses.The parent-offspring correlation for the traits, starch content and tuber number, is significant at 0.01 level. The regrssion equations are Y (mp-F1)=1.0 + 1.2x and Y (mp - F1) = 5.3 + 0.8x, respectively. The 2n pollen-producing clones play an impotant role in increasing tuber stach content.Estimates of the combining ability for the main yield components indicate that additive effect prodominatcs for such trais as plot yield, tuber weight per plant and starch content, whereas both additive and non-additive effects lay equal stress on mean tuber weight and non-additive effect is important for tuber number. In general, non-additive effect appears to be important in the progenies of 4x-2x crosses.Tuber number shows apparent heterosis while mean tuber weight dos not. Thus, it is necessary for 2n pollen-producing clones to be selected for high mean tuber weight and low tuber number before their use in commercial potato production.In the double cropping region of Anhui, the 4x - 2x hybrids seem to be more adaptive than S. tuberosum x S. andigena hybrids, but the yield of 4x - 2x cross is lower than that of the cross S. tuberosum x S. andigena in Harbin region.In Harbin region, the better combination type is in the from of S. andigena x (phureja-haploid Group tuberosum), and the best cross is also in the from. In Anhui, the better combination type is S. tuberosum x (phureja - haploid Group tuberosum), and the best cross is that using a variety of S. tuberosum as its parent. The progeny tubers of 4x - 2x cross have a short dormant period and are suitable for the double cropping region.
文摘Neo-tuberosum derived from S. tuberosum ssp. andigena is a very important genetic resource in potato breeding. In 1970′s, Neo-tuberosum clones were introduced into China and improving programs were started at that time. The improved clones of it were obtained through recurrent selection in different latitudes of China. According to obvious heterosis appeared in crossing with common potato varieties, Neo-tuberosum would be good parents for breeding and true potato seed (TPS) production. Dihaploid of Neo-tuberosum were obtained by parthenogenesis, and its male fertility was recovered by crossing with S. phureja as male parents. Using acceptable improved Neo-tuberosum clones as a parent, the tuber yield of TPS population was increased greatly.
