Pub Date : 2008-01-01DOI: 10.31274/RTD-180813-16647
Stephanie Rose Kadlicko
Since the discovery of the pest in 1992, western corn rootworm (Diabrotica virgifera virgifera LeConte (WCR)) populations in Serbia have successfully been kept low with crop rotation. This has reduced the efficiency of screening maize for WCR resistance. A coop- erative project between Iowa State University and the Maize Research Institute, Zemun Polje evaluated 13 Ser- bian commercial maize varieties in Ames, Iowa over a two-year period using the difference approach. Maize hy- brids were planted on trap crops where high WCR popu- lations were assumed. Hybrids were evaluated for WCR resistance using a randomized complete block design with four replications. Treatments were paired-rows arranged in split plots with one row in each pair treated with insecticide and the other row left untreated. WCR in- jury was evaluated using a rating of root size and root re- growth (1-6 scale), root injury (0-3 Node-Injury Scale), root mass, lodging, and yield. The results indicated signif- icant differences among the Serbian hybrids in the pres- ence of moderate-to-high levels of western corn root- worms. The relative benefit of insecticide treatments for maize hybrids was a useful tool in evaluating resistant germplasm. However, conducting analyses on relative dif- ferences between insecticide treated and untreated plots was not as effective at detecting differences as comparing the plots independently.
{"title":"Evaluation of Serbian commercial corn hybrid tolerance to feeding by larval western corn rootworm (Diabrotica virgifera virgifera Leconte) using the novel difference approach","authors":"Stephanie Rose Kadlicko","doi":"10.31274/RTD-180813-16647","DOIUrl":"https://doi.org/10.31274/RTD-180813-16647","url":null,"abstract":"Since the discovery of the pest in 1992, western corn rootworm (Diabrotica virgifera virgifera LeConte (WCR)) populations in Serbia have successfully been kept low with crop rotation. This has reduced the efficiency of screening maize for WCR resistance. A coop- erative project between Iowa State University and the Maize Research Institute, Zemun Polje evaluated 13 Ser- bian commercial maize varieties in Ames, Iowa over a two-year period using the difference approach. Maize hy- brids were planted on trap crops where high WCR popu- lations were assumed. Hybrids were evaluated for WCR resistance using a randomized complete block design with four replications. Treatments were paired-rows arranged in split plots with one row in each pair treated with insecticide and the other row left untreated. WCR in- jury was evaluated using a rating of root size and root re- growth (1-6 scale), root injury (0-3 Node-Injury Scale), root mass, lodging, and yield. The results indicated signif- icant differences among the Serbian hybrids in the pres- ence of moderate-to-high levels of western corn root- worms. The relative benefit of insecticide treatments for maize hybrids was a useful tool in evaluating resistant germplasm. However, conducting analyses on relative dif- ferences between insecticide treated and untreated plots was not as effective at detecting differences as comparing the plots independently.","PeriodicalId":49850,"journal":{"name":"Maydica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82451619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-01-01DOI: 10.31274/RTD-180813-11005
B. L. Peiris
Haif-sih and full-sib reciprocal recurrent selection (RRS) have been successful methods of reciprocal improvement of two maize (Zca mays L.) populations to maximize the performance of the population cross. The objective of our study was to use computer simulation to compare responses to selection of populations themselves and their crosses for half-sib and full-sib RRS and one modification. The modification included an additional generation of inbreeding before producing testcrosses (S 2 plants as recombination units). Parental populations included 110 individuals throughout 20 cycles of selection. Evaluation of each individual in both RRS methods was based on the mean performance of 10 testcross progeny. Selection intensity was 10% in all instances. Assumptions for the simulation studies included diploid individuals with two alleles per locus, where expression of the quantitative trail was determined by 40 independent loci; genotype x environmental interaction was not included. There were 22 initial conditions corresponding to two sets of initial parental population allele frequencies and 11 genetic models. The two sets of initial parental populations were equal and unequal allele frequencies. The 11 genetic models included additive genetic variance, three levels of dominance, and seven epistasis combinations. Half-sib and full-sill RRS and their modification were simulated for each of the 22 initial conditions with three replications of each condition for 20 cycles of RRS selection. Genetic response of full-sib RRS was similar to half-sib RRS for 21 initial conditions with S 1 s as the recombination units. The linear response of half-sib RRS was 1.7 times (P ≤ 0.01) greater than full-sib RRS for the genetic model that included complete dominance and dominance x dominance epistasis with S 1 recombination units. There were no significant differences between half-sib and full-sib RRS with S 2 s as recombination units but use of S 2 s increased selection response for both half-sib and full-sib RRS. Compared with half-sib RRS, full-sib RRS requires 50% fewer test-crosses, but full-silo RRS has the same selection response as half-sib RRS. Full-silo RRS with S 2 s as the recombination units would lie the more efficient method of interpopulation improvement in maize breeding.
{"title":"Comparison of half-sib and full-sib reciprocal recurrent selection and their modifications in simulated populations","authors":"B. L. Peiris","doi":"10.31274/RTD-180813-11005","DOIUrl":"https://doi.org/10.31274/RTD-180813-11005","url":null,"abstract":"Haif-sih and full-sib reciprocal recurrent selection (RRS) have been successful methods of reciprocal improvement of two maize (Zca mays L.) populations to maximize the performance of the population cross. The objective of our study was to use computer simulation to compare responses to selection of populations themselves and their crosses for half-sib and full-sib RRS and one modification. The modification included an additional generation of inbreeding before producing testcrosses (S 2 plants as recombination units). Parental populations included 110 individuals throughout 20 cycles of selection. Evaluation of each individual in both RRS methods was based on the mean performance of 10 testcross progeny. Selection intensity was 10% in all instances. Assumptions for the simulation studies included diploid individuals with two alleles per locus, where expression of the quantitative trail was determined by 40 independent loci; genotype x environmental interaction was not included. There were 22 initial conditions corresponding to two sets of initial parental population allele frequencies and 11 genetic models. The two sets of initial parental populations were equal and unequal allele frequencies. The 11 genetic models included additive genetic variance, three levels of dominance, and seven epistasis combinations. Half-sib and full-sill RRS and their modification were simulated for each of the 22 initial conditions with three replications of each condition for 20 cycles of RRS selection. Genetic response of full-sib RRS was similar to half-sib RRS for 21 initial conditions with S 1 s as the recombination units. The linear response of half-sib RRS was 1.7 times (P ≤ 0.01) greater than full-sib RRS for the genetic model that included complete dominance and dominance x dominance epistasis with S 1 recombination units. There were no significant differences between half-sib and full-sib RRS with S 2 s as recombination units but use of S 2 s increased selection response for both half-sib and full-sib RRS. Compared with half-sib RRS, full-sib RRS requires 50% fewer test-crosses, but full-silo RRS has the same selection response as half-sib RRS. Full-silo RRS with S 2 s as the recombination units would lie the more efficient method of interpopulation improvement in maize breeding.","PeriodicalId":49850,"journal":{"name":"Maydica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81371957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-01-01DOI: 10.31274/RTD-180813-11674
J. S. Castellanos, A. Hallauer, H. Córdova
Tesrcross evaluarion is used to determine the relative potential of corn (Zea mays L.) lines in a hyhrid hreeding program. Choice o f rester is important fo r effi cient selection :IITIong lines for their potential in hybrids. Testcrosses among 21 lines and seven testers were evalUat ed at se ven environments in Guatemala. The experimental des ign was a randomized complete block with a split-plot arrangement. where lines were assigned to whole plots and testel.'> to subplots. The objectives of the study w ere to ohtain informatio n for choice o f testers and to identify the more convenient tester to use in early tes ting for a hyhrid program in which three-way and double-cross hybrids ,He commonly used . Data for yield and agronomic traits were recorded. but the combined analysis for yield (r/ ha) was th e main trait of interest. Differences among lines and :lmong testers across environments w ere highly significant (I' :s; 0.01). Highly significant differences t()r the testers x lines interaction indicateci that the te sters ranked the lines differently. Coefficient of concordance (1(1) and Pea rson correlations (I') suggested that the ranking of lines across testers was relatively consistent. Testcrosses with a single cross had the greatest average yield (6.48 t/ ha). Based on the v:niance among testcrosses. estimates of general C0111 hining ability. correlatio n with the other testers, and ac cept:lble performance itself, the single c ross tester was sug gested as the tester for the hybrid breeding program in Guatemala. Lines with good general combining ability for different hybrid combinations were identified. Three-way testcrosses superi or to the hes t check (lCTA HB-85) w ere icientified for further evaluat ion as potential new hybrids for release. Significant correlations between yield and dis eases (Southern corn rust caused hy Puccinia po~ysorct L:nclerw. and Northern corn lelf hlight caused by Exserohi /11111 lurcicul1I Pass. = Helmintbo.,poriul1l t"rcicllm Pa ss.)
{"title":"Relative performance of testers to identify elite lines of corn (Zea mays L.)","authors":"J. S. Castellanos, A. Hallauer, H. Córdova","doi":"10.31274/RTD-180813-11674","DOIUrl":"https://doi.org/10.31274/RTD-180813-11674","url":null,"abstract":"Tesrcross evaluarion is used to determine the relative potential of corn (Zea mays L.) lines in a hyhrid hreeding program. Choice o f rester is important fo r effi cient selection :IITIong lines for their potential in hybrids. Testcrosses among 21 lines and seven testers were evalUat ed at se ven environments in Guatemala. The experimental des ign was a randomized complete block with a split-plot arrangement. where lines were assigned to whole plots and testel.'> to subplots. The objectives of the study w ere to ohtain informatio n for choice o f testers and to identify the more convenient tester to use in early tes ting for a hyhrid program in which three-way and double-cross hybrids ,He commonly used . Data for yield and agronomic traits were recorded. but the combined analysis for yield (r/ ha) was th e main trait of interest. Differences among lines and :lmong testers across environments w ere highly significant (I' :s; 0.01). Highly significant differences t()r the testers x lines interaction indicateci that the te sters ranked the lines differently. Coefficient of concordance (1(1) and Pea rson correlations (I') suggested that the ranking of lines across testers was relatively consistent. Testcrosses with a single cross had the greatest average yield (6.48 t/ ha). Based on the v:niance among testcrosses. estimates of general C0111 hining ability. correlatio n with the other testers, and ac cept:lble performance itself, the single c ross tester was sug gested as the tester for the hybrid breeding program in Guatemala. Lines with good general combining ability for different hybrid combinations were identified. Three-way testcrosses superi or to the hes t check (lCTA HB-85) w ere icientified for further evaluat ion as potential new hybrids for release. Significant correlations between yield and dis eases (Southern corn rust caused hy Puccinia po~ysorct L:nclerw. and Northern corn lelf hlight caused by Exserohi /11111 lurcicul1I Pass. = Helmintbo.,poriul1l t\"rcicllm Pa ss.)","PeriodicalId":49850,"journal":{"name":"Maydica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88400546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1993-01-01DOI: 10.31274/RTD-180813-12230
L. Michelini, A. Hallauer
Exotic germplasm may be used to increase the genetic variability in the U.S. maize populations. The objectives of this study were to determine the relative performance of exotic germplasm to two widely used U.S. Corn Belt populations, to determine the proportions of exotic to adapted germplasm that exhibited superior performance, and to determine the heterotic patterns between the exotic populations and the two widely used Corn Belt populations. A 13x13 simple lattice design was used and the study was conducted in seven Iowa environments. The treatments included the adapted (0% exotic) and exotic germplasm (100% exotic), the crosses (50% exotic) and backcrosses (75% or 25% exotic germplasm) between them, and the check varieties. The results for grain yield (q/ha) suggest that the best percentage of exotic germplasm used was 50%. Exceptions were observed in the crosses of Cateto by BS26 (51.5 q/ha), Caribbean Flint by BS26 (56.1 q/ha), where the highest yield was observed for no exotic germplasm, BS26 (57.1 q/ha), and in the cross of Tuxpeno by BS26, where the highest yield was observed for the treatment with 25% exotic germplasm (58.8 q/ha). Suwan 1 and Tuxpeno exotic germplasms have greater potential for continuing development. Both germplasms had mild selection for adaptation in the U.S. Corn Belt compared with the other exotic germplasms. Despite no selection for adaptation and without considering the reciprocal crosses, the crosses Tuxpeno by BS13 (72.0 q/ha) and BS13 by Suwan 1 (69.1 q/ha), ranked fourth and fifth in the treatments per se, where the top ranked treatment was the
{"title":"Evaluation of exotic and adapted maize (Zea mays L.) germplasm crosses.","authors":"L. Michelini, A. Hallauer","doi":"10.31274/RTD-180813-12230","DOIUrl":"https://doi.org/10.31274/RTD-180813-12230","url":null,"abstract":"Exotic germplasm may be used to increase the genetic variability in the U.S. maize populations. The objectives of this study were to determine the relative performance of exotic germplasm to two widely used U.S. Corn Belt populations, to determine the proportions of exotic to adapted germplasm that exhibited superior performance, and to determine the heterotic patterns between the exotic populations and the two widely used Corn Belt populations. A 13x13 simple lattice design was used and the study was conducted in seven Iowa environments. The treatments included the adapted (0% exotic) and exotic germplasm (100% exotic), the crosses (50% exotic) and backcrosses (75% or 25% exotic germplasm) between them, and the check varieties. The results for grain yield (q/ha) suggest that the best percentage of exotic germplasm used was 50%. Exceptions were observed in the crosses of Cateto by BS26 (51.5 q/ha), Caribbean Flint by BS26 (56.1 q/ha), where the highest yield was observed for no exotic germplasm, BS26 (57.1 q/ha), and in the cross of Tuxpeno by BS26, where the highest yield was observed for the treatment with 25% exotic germplasm (58.8 q/ha). Suwan 1 and Tuxpeno exotic germplasms have greater potential for continuing development. Both germplasms had mild selection for adaptation in the U.S. Corn Belt compared with the other exotic germplasms. Despite no selection for adaptation and without considering the reciprocal crosses, the crosses Tuxpeno by BS13 (72.0 q/ha) and BS13 by Suwan 1 (69.1 q/ha), ranked fourth and fifth in the treatments per se, where the top ranked treatment was the","PeriodicalId":49850,"journal":{"name":"Maydica","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"1993-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85263952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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