Contribution of growth rate and harvest index to grain yield of oats (Avena sativa L.) following selfing and outcrossing of M1 plants

Summary Three populations of oats, each with 790 lines, were derived from CI 7555: (a) one (M population) consisted of M₂-derived lines obtained from EMS treatment of naked seeds, (b) one (O population) consisted of F₂-derived lines from crosses of M₁ with check plants, and (c) one (C population) consisted of check lines.About 98% of the grain yield (GYD) variation in each population was due to variation in growth rate (GR) and harvest index (HI).There was greater variation for both GR and HI in M and O than in the C population, showing that mutations were induced for both traits. Generally, mutations for these two traits were for reduced expression: high HI and GR are desired in a practical oat breeding program, so most induced mutations were deleterious.Mutation breeding, either with direct selection or outerossing to release the induced mutations, does not appear to be a desirable method for improving GR or HI of oats.Journal Paper No. J-9308 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa 50011. Project No. 1752. This work was supported in part by the International Atomic Energy Agency. Vienna. Austria, in the form of a fellowship for the senior author.National University of Malaysia, Kuala Lumpur, Malaysia (formerly Visiting assistant Professor in Agronomy, Iowa State University).     

Performance of Avena sativa L./Avena fatua L. Backcross lines

Summary Although wild oats (Avena fatua L.) have been considered a potential source of genes for cultivated oat (Avena sativa L.) improvement, most progenies of A. sativa/A. fatua crosses have weak straw and are very susceptible to crown rust (Puccinia coronata CDA. var. avenae Fraser and Led.). Backcrossing to A. sativa has been suggested as a method of improving progeny lines while introducing new genes from wild oats to cultivated oats. In this study, A. sativa/A. fatua F₁ hybrids were backcrossed twice to A. sativa, and lines from three backcross populations were selected on the basis of agronomic performance in segregating generations. The A. sativa recurrent parents were Dal (tall and late) and Stout (short and early).Backcross lines and recurrent parents were evaluated in five performance trails from 1983 through 1985. There was significant variation among backcross lines for most traits, but most backcross lines did not produce higher grain and straw yields than their A. sativa parent. Several backcross lines were higher than their recurrent parent in test weight and groat percentage. A line derived from Stout, 175BC2-6, was considered the most promising backcross line in the study. This line produced more grain, had heavier kernels, and headed 3.3 days earlier than Stout. Although 175BC2-6 does not have sufficient straw strength and crown rust resistance to be released as a cultivar, it is considered to be a new source of high grain yield, high test weight and earliness for oat breeding.     

Repeatability of regression stability indexes for grain yield of oats (Avena sativa L.)

Summary Two lines of descent were established from an F₃ bulk lot of oats (Avena sativa L.) initiated by mixing seeds from approximately 250 crosses. For one line of descent, seeds were radiated with thermal neutrons or X-rays from F₃ through F₆, followed by five generations of bulk propagation. The second was propagated for 10 generations. No artificial selection was practiced in either line of descent. Grain yield data from 20 random strains from each of four generations from the radiated (F₇, F₈, F₉, and F₁₁) and five from the nonradiated (F₃, F₆, F₇, F₈, and F₁₂) line of descent and 20 check cultivars tested in 14 environments were used for estimating regression stability indexes of oat strains.The 14 environments were assigned randomly to two sets of seven, and regression stability indexes were computed for the 180 experimental oat strains for both sets. Intrageneration correlations between regression stability indexes from the two sets of environments ranged from –0.35 to 0.64 (18 d.f.), and only one of nine was significant, indicating poor repeatability for estimates of this statistic computed from different sets of environments.Correlations between regression stability indexes from two sets of environments, one in which the environments varied by soil nitrogen levels and a second in which they varied by soil phosphorus levels, ranged from –0.01 to 0.28, none of which was significant.The relative magnitudes and ranking of the regression stability index values for the oat genotypes were nearly identical when environmental productivity indexes were assessed with any number of check cultivars from 2 to 20.Journal paper No. J-8080 of the Iowa Agriculture and Home Economics Experiment Station. Ames. Iowa. USA 50010. Project 1752.     

Effects of S1-recurrent selection for protein yield on seven agronomic traits of oat

Summary Three S₁-recurrent selection programs (designated HG, HP, and HGP) for increasing protein yield of oat (Avena sativa L.) were conducted for five cycles of selection. The selection criteria in each program (line of descent) emphasized different components of protein yield; high grain yield in HG, both high protein concentration of the groats (caryopsis) and high grain yield in HP, and high protein yield per se in HGP. Heading date and height were restricted to no net change. The objectives of this study were to evaluate the agronomic performance of these three lines of descent and the correlated responses in agronomic traits due to selection. Thirty to sixty random S₀-derived lines from each cycle and ten check lines were grown in hill-plot experiments at two locations in 1989. Grain yield increased in all three lines of descent; HG showed the greatest rate of gain followed by HGP and then HP (0.20, 0.10, and 0.07 Mg ha^-1 per cycle, respectively). Test weight decreased in HGP by 2.6 kg m^-3 per cycle and in HP by 4.0 kg m^-3 per cycle, but remained constant in HG. Cycle 5 (C₅) means for straw yield, height, and seed weight were not significantly different from the C₀ means for any line of descent. Groat percent remained unchanged in HGP, increased from 70.1 to 71.7% in HG, and decreased from 69.9 to 67.6% in HP. Heading date decreased by 3 d in HG and HGP, but remained unchanged in HP. HG compares most favorably with commercial cultivars because of its high yield and acceptable agronomic traits, while HP tends to be low in test weight, seed weight, and groat percent.Abbreviations BM- above ground biomass - GP- groat (caryopsis) percent, fraction of average seed weight that is groat rather than hulls - GPC- groat-protein concentration - GPY- groat-protein yield - GTY- groat yield - GY- grain yield - HD- heading date - HG- selection for protein yield through high grain yield - HGP- selection for protein yield per se - HP- selection for protein yield through high grain yield and high groat-protein concentration - HT- height - PY- protein yield - SDWT- seed weight - SY- straw yield - TWT- test weight     

Quantitative trait loci for quality and agronomic traits in two advanced backcross populations in oat (Avena sativa L.)

Using the advanced backcross quantitative trait loci (AB‐QTL) strategy, we successfully transferred and mapped valuable allelic variants from the high β‐glucan (BG) accession IAH611 (PI 502955), into the genome of cultivar ‘Iltis’. By backcrossing one BC₁F₁ plant to ‘Iltis’, we developed two BC₂F_2‐6 populations A and B, comprising 98 and 72 F₂‐individuals, respectively. Genotyping of BC₂F₂ individuals with predominantly AFLP markers resulted in 12 linkage groups with a map size of 455.4 cM for Population A and 11 linkage groups with a map size of 313.5 cM for Population B. Both populations were grown at three sites in Germany over a three‐year period. Individuals were then phenotyped for 13 traits including grain yield (YD) and β‐glucan content (BG). QTL analysis via stepwise regression detected a total of 33 QTLs, most of which were clustered in three linkage groups. Two dense linkage groups A1 and B13 were found to be putatively homologous to groups KO_6 and KO_11 of the ‘Kanota’/‘Ogle’ map, respectively.     

Expression of nuclear-cytoplasmic interactions and heterosis in quantitative traits of oats (Avena spp.)

Summary Nuclear and cytoplasmic genes from 10 diverse Avena sterilis L. accessions were introgressed into four Corn Belt oat (A. sativa L.) cultivars. Grain and straw yield, harvest index, heading date, height, unit straw weight, and vegetative growth index were evaluated in the BC₂ generation of 76 cytoplasmic isopopulations. Means of all seven traits in the BC₂ of Tippecanoe matings were greater than Tippecanoe due to introgression of A. sterilis germplasm, whereas means of all seven traits in BC₂ populations of Ogle were inferior to those of Ogle. BC₂ populations of matings involving CI 9170 and CI 9268 were variable, with some trait means being greater than those of the recurrent parents and some being lower.The phenomena of nuclear-cytoplasmic interaction effects and nuclear-cytoplasmic heterosis also were investigated. In matings where significant differences were present between cytoplasmic isopopulations, those with A. sterilis cytoplasm usually were superior, but no trait exhibited a consistent cytoplasmic effect across all matings. These results suggest that all seven traits were influenced by nuclear-cytoplasmic interactions. Nuclear-cytoplasmic heterosis for grain yield was present in two of 38 isopopulations with A. sterilis cytoplasm; both were from matings involving Tippecanoe. Nuclear-cytoplasmic heterosis for each of the remaining traits was observed in four to eight of the 38 isopopulations with A. sterilis cytoplasm.     

Relationship between genealogical distance and breeding behaviour in oats (Avena sativa L.)

Summary Eight oat cultivars and experimental lines from four germplasm sources were crossed in a diallel mating design without reciprocals. F₁ heterosis for grain yield was evaluated in two experiments, and 48 F₂-derived lines from each of the 28 matings were evaluated for bundle weight, grain yield, straw yield, harvest index, height, and heading date in two experiments. Number of transgressive segregates per trait and generalized genetic variance were calculated for each mating. Genealogical distance for each mating was obtained by using coefficient of kinship based on the pedigree of the parents. The relationship between genealogical distance and the three types of breeding behaviour was examined via correlation and regression. Significant correlations occurred only for genealogical distance with numbers of transgressive segregates for height and with generalized genetic variances. Both were positive. Significant heterosis was observed for matings of more distantly related parents. Regressions on genealogical distance, when significant, were linear. Genealogical distance between parents was positive associated with diversity on the basis of breeding behavior.Journal Paper No. J-11874 of the Iowa Agriculture and Home Economics Station, Iowa State Univ., Ames, IA 50011. Project 2447.     

Inheritance of groat protein percentage in Avena sativa L. × A. Fatua L. Crosses

Summary Gene action and heritability of groat protein percentage were determined in F₁, F₂, and F₃ generations of nine crosses between three Avena sativa L. cultivars and three A. fatua L. selections. Relationships among groat protein percentage, grain yield, and 100-seed weight also were evaluated. The three A. sativa parents were Dal (high grain yield and intermediate groat protein percentage), Goodland (low grain yield and high groat protein percentage), and Stout (high grain yield and low groat protein percentage). The three A. fatua parents were chosen for the study on the basis of vigorous plant growth and high groat protein percentage. The study was conducted at Madison, Wisconsin in 1979 and 1980.There was partial dominance towards low groat protein percentage. Narrow sense heritability estimates for groat protein percentage were low in Dal and Goodland crosses and intermediate in Stout crosses. In the F₂ generation, groat protein percentage was significantly higher in shattering than in nonshattering plants in 1979, but not in 1980. There were significant, positive correlations between groat protein percentage, 100-seed weight, and grain yield in F₁ and F₂ generations, but they were not large numerically. Relationships among these traits were either negative or nonsignificant in the F₃ generation. Although our results indicated that selection for higher groat protein percentage is possible when a low protein A. sativa cultivar is used, most of our simple cross progenies from A. sativa x A. fatua crosses had weak straw and were susceptible to crown rust (Puccinia coronata Cda. var. avenae Fraser and Led.).     

Association of gene for grain colour with monosome XIV of Avena sativa L.

Summary The F₂'s from crosses between Dyfed (S.240; a black grained cultivar) and monosomics of Sun II (non-black cultivar) were analysed. With the exception of F₂ progenies involving monosomes, II, VI, VII, X, XI, XII, XIII and XIV, all other deviated from the genetic ratio 3 black: 1 non-black. The cytological examination of the non-black individuals belonging to those families that did not deviate from the 3:1 ratio showed that they were either 41- or 42-chromosome plants. However, non-black individuals involving monosome XIV were 40-chromosome plants. The gene conferring the black colour to the grains in Avena sativa cv. Dyfed (S.240) is located on chromosome XIV.Department of Plant Breeding and Genetics, Sind Agriculture University. Tando Jam. Pakistan.     

Grain yield response and stability for oat lines with low-, medium-, and high-yielding ability

Summary Relationships that exist among grain yielding ability and response and stability of grain yields when tested over variable environments were examined. Two sets of oats lines were tested over many environments that had wide ranges in productivities. The lines in each set were divided into high-, medium-, and low-yielding groups on the basis of means across all environments, and variance components for genotype × environment interactions and means of regression responses and coefficients of determination were computed for the three yield categories in each set.Mean grain yields for the high-, medium-, and low-yielding groups across both sets of oats lines were 2.7, 2.3, and 1.9 Mg ha^-1, respectively. Coefficients of variability for the genotype × environment interaction were 18%, 16%, and 12% for the high-, medium-, and low-yielding categories, respectively. Means for regression responses were 1.22 for the high group, 0.99 for the medium, and 0.78 for the low. Most responses for the high and low groups were significantly different from 1.0. Means for coefficients of contingency were 0.63, 0.56, and 0.51 for the high-, medium-, and lowyielding groups, respectively.There was a positive relationship between mean grain yield and response of grain yield to improving environments. Thus, high yielding lines are also the responsive lines. Our study gave conflicting results about stability of production for the three yield groups. Coefficients of variation for genotype × environment interaction indicated that the high-yielding group was more interactive with environments than were the medium- and low-yielding ones: However, the means for coefficients of contingency indicated that the high yielding group was the most stable.Journal Paper No. J-12128 of the Iowa Agric. and Home Econ. Exp. Stn., Ames, IA 50011. Project 2447.     

Domestication of the protein-rich tetraploid wild oats Avena magna and A. Murphyi

Summary The first stage in the domestication of the protein-rich tetraploid oats Avena magna and A. murphyi has been achieved by introducing seed non-shattering from the cultivated hexaploid oats A. sativa. A great variation in the protein content was encountered in the tetraploid domesticated types and plants having up to 27 31% protein were selected. The potential of these newly domesticated oats in increasing protein yields is briefly diseussed: also the significance of the tetraploids A magna and A. murphyi in improving the protein content of the hexaploid cultivars is stressed.     

Unfecund, gigantic mutant of oats (Avena sativa) shows fecundity overdominance and difference in DNA methylation properties

Summary The fecundity heterosis of the gig/+oats (Avena sativa) was examined in a population showing segregation of the gene under the long photoperiods in S Finland. Segregating isolines of cv Hannes and of cv Kyrö were raised at two plant densities and the grain yield of heterozygotes and nonmutant homozygotes were evaluated. The heterozygotes in mean outyielded the homozygotes. The overdominance of grain number explains the persistance of this mutant at a relatively high frequency in oats in Finland, though the fecundity of the extremely late homozygous mutant is zero. Previous and current data indicate that the heterozygotes show heterosis of fecundity depending on genetic background, season or other environmental conditions. Grafting of cut stems of nonmutants onto wounded nodes of mutants did not transfer any observable florescence inductor. Hypomethylation of DNA, as revealed with HpaII digestion, occurred in topmost leaves of non-mutants, being absent or occurring to a lesser extent in the comparative leaves of mutants.     

The introgression of characters of the wild oat Avena magna (2n=4x=28) into the cultivated oat A. sativa (2n=6x=42)

Summary A study of derivatives from the hybrid Avena sativa × A. magna backcrossed to A. sativa clearly indicate that it is possible to introduce characters of the wild oat into the cultivated oat. Progeny with improved grain characters and crude protein content of the groat have been isolated and their use as breeding material is discussed.     

Inheritance of groat-oil content and high-oil selection in oats (Avena sativa L.)

Summary The potential for breeding for high groat-oil content in oats was investigated by (a) conducting generation means analyses on data from three matings among adapted Avena sativa L. cultivars, (b) practicing one cycle of phenotypic recurrent selection in a segregating population derived from eight species backcrosses (Avena sativa x (A. sativa x A. sterilis)) among 24 parents, and (c) identifying transgressive segregates from interspecific (A. sativa x A. sterilis) matings.Additive gene action was the most important component in explaining the variation among generation means for groat-oil content. Dominance and epistatic interactions involving dominance were not significant in any mating. Significant residual genetic variation occurred in one mating, even after additive, dominance, and three digenic interactions were fitted. The importance of additive genes action implies that desired allelic combinations for high groat-oil content can be obtained in pure-line cultivars.One cycle of phenotypic recurrent selection using single plants as the selection units resulted in a genetic gain of 1.7 to 2.1% in groat-oil content. Individual plants selected for initiating the second cycle had from 9.5 to 12.6% groat oil.Over all 12 interspecific matings, the F₂ progeny means were similar to the midparent values. Only two were significantly deviant. Transgressive segregates for high and low groat-oil content from these matings provided evidence that A. sterilis possesses alleles for high and low groat-oil content that are different from those in the gene pool of cultivated oats.Journal Paper No. J-11340 of the Iowa Agric. and Home ECon. Exp. Stn., Ames, Iowa 50011. Project 2447. This study was supported in parts by grants from the Iowa Committee for Agricultural Development and the International Harvester Company.     

Increasing grain yield of oats by independent culling for harvest index and vegetative growth index or unit straw weight

Summary Most variation in grain yield of oats is due to variation in harvest index and vegetative growth index, but the latter traits are negatively associated. Therefore we used independent culling levels to select oat genotypes with high levels of vigor traits and a desirable level of harvest index in an attempts to maximize grain yield. Harvest index and vegetative growth index or harvest index and unit straw weight were selected at various culling levels. Intensive selection for harvest index resulted in high harvest index but no grain yield improvement, because the selected lines had poor vigor. Intensive selection for vegetative growth index or unit straw weight resulted in high biomass but low harvest index.The most effective combination of culling levels was to select 25% of the original population for harvest index and, subsequently, to select for vegetative growth index or unit straw weight at an 8% intensity in the remnant population.Journal Paper No. J-11272 of the Iowa Agric. and Home Econ. Exp. Stn., Ames, IA 50011. Project 2447. This work was supported in part by the World Food Institute, Iowa State Univ., in the form of a Senior Fellowship for the senior author.     

Associations among productivity,production response,and stability indexes in oat varieties

Summary We tested three sets of oat varieties for grain yield in a series of environments and observed that generally more than 80% of the yield variation for individual varieties was due to linear regression response. Mean yields for varieties were significantly variable in all three sets, and regression response indexes were significantly variable in two of them.Mean yields over the three sets were correlated with regression response indexes with r=0.61. Associations of mean yield with the three stability parameters (i.e., coefficient of determination, mean square for deviations from regression, and ecovalence) were low and usually not significant. The correlation of regression response indexes with coefficients of determination was 0.42, but neither of the other stability parameters was associated with the response indexes. The three stability parameters were closely correlated with one another.Our materials were selected varieties, so evidently our results suggest what can be accomplished in breeding for combinations of mean production, production response, and productiom stability.Journal Paper No.J-9092 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, USA 50011. Project 1752. This work was supported in part by the International Atomic Energy Agency, vienna, Austria, in the form of a fellowship for the senior author.     

Interfering with regular meiotic behaviour in Avena sativa as a method of incorporating the gene for mildew resistance from A. barbata

Summary The regular meiotic behaviour of the cultivated oat Avena sativa (2n=6x=42) is genetically controlled. The factors which control the diploid-like meiotic behaviour also restrict the amount of pairing that occurs between alien chromosomes and their homoeologues in A.sativa, and hence increases the difficulties of introducing desirable variation from wild species into the cultivated oat. A genotype of the diploid species A.longiglumis which interferes with the regular meiotic behaviour of A. sativa can be used to induce pairing between alien chromosomes and their corresponding chromosomes in A. sativa. Using this procedure the dominant gene conferring mildew resistance has been transferred from the tetraploid weed species A. barbata into the cultivated oat.     

The structure and breeding behaviour of a translocation involving the transfer of mildew resistance from Avena barbata Pott. into the cultivated oat

Summary The gene for mildew resistance has been succesfully transferred into the cultivated oat from the wild oat species Avena barbata by means of an irradiation-induced translocation. The translocation has been shown to involve the long arm of chromosome ST21 of A. sativa, the short arm, the centromere and a segment of the long arm of the barbata chromosome.The transmission of the translocation is normal in the cultivar Manod in which it was originally isolated. When the translocation was transferred into other cultivars of oats, transmission through the male gametes was found to be impaired in some genotypic backgrounds. However, there was no evidence that the translocation had any deleterious effect on development and fertility in a range of cultivars.The translocation was shown to involve an exchange between nonhomoeologous chromosomes.The behaviour of the translocation in diverse genotypes indicated that the translocation was a new source of mildew resistance that could be easily used in a breeding programme.     

Protein yield of oats as determined by protein percentage and grain yield

Summary Relationships among the traits protein percentage, grain yield, and protein yield of oats were studied with F₂-derived lines in F₃ and F₄ from 27 matings obtained by crossing high-protein with high-yield oat lines. High-protein parents were (a) selections from an Avena sativa bulk, (b) selections from three-way matings in which an initial parent was A. sterilss, and (c) cultivars. High-yield parents were derived from backcross populations involving A. sterilis accessions as donor parents.Significnnt genetic variation existed among F₂-derived lines for grain and protein yield in all matings and for protein percentage in all but one mating.Protein percentage had a highly significant negative correlation with grain yield (r=–0.33^**) when pooled over all matings, but in five, these two traits were not correlated. Overall, protein percentage showed a small negative correlation with protein yield (r=–0.09^*), and protein and grain yields had a high positive association (r=0.98^**). F₂-derived lines with both high protein percentage and high grain yield were obtained.High transgressive segregates for protein percentage occurred in two matings, for grain yield in nine, and for protein yield in 14. Most high transgressive segregates for protein yield were high because of high grain yield only, but in four matings, lines were found where protein yield was increased by concurrent increases in both protein percentage and grain yield.Only a few specific parental combinations between high-protein and high-yield parents produced segregates in which increased protein percentage contributed materially to high-protein yields.Journal Paper No. J-11264 of the Iowa Agriculture and Home Economics Experiment Stn., Ames, Iowa 50011. Project 2447.