Yield Of Progeny Research Articles

Studies On the Applicatlon of Male Sterility to Alfalfa Breeding : Heterosis and Combining Ability

Degree of heterosis and relative value of GCA and SCA were discussed in the crosses between male sterile plants and normal plants and between normal plants and normal plants. One hundred and eight hybrids produced by crossing 17 cytoplasmic male sterile plants with 19 normal plants, 158 hybrids produced by crossing 15 normal plants with 18 normal plants and 13 S1 progenies were evaluated with the spaced-planting condition (O.5mXO.25m) for plant height, yielding ability and fall vigor in 1974 and 1975. Forage yields of S1 progenies were quite low and the ratios of mean yield of S1 progeny to mean yield of crossed progenies of their parental plants were 80.4%, 74.6% and 76.2% in total yield in 1974, 1975 and total yield of two years, respectively. MSXNor progenies of which maternal parents were male sterile showed higher yield than NorxNor progenies of which maternal parents were normal. Twenty three hybrids outyielded the check variety, Dupuits by 20% or more and 9 hybrids outyielded DuPuits by 30% or more. GCA in fall vigor was particularly important and it was also important in plant height and yield. SCA was considerably important in plant height and yield and among them, it was relatively more important in first harvest in 1974 and 1975. In pooled population of MS×Nor and Nor×Nor, variance components due to female parents, σ2F greater than those due to male parents, σ2hi. Variance components due to male parents, σ2N for fall vigor, second harvest in 1974 and third harvest in 1975 were greater than those due to female parent, σ2F in MSxNor population. Relative importance of GCA due to male parents in MSXNor population was great in these characteristics. Ratios of genotypic variance to phenotypic variance in fall vigor and second harvest in 1974 were relatively high and those magnitudes ranged from 61.8% to 69.7% SCA variances in these characteristics were especially low.

Method of Diplandroid Formation and Yield of Progeny from Reciprocal (4x-2x) Crosses1

Abstract In 6 families of reciprocal crosses involving 3 tetraploid (2n = 4x = 48) cultivars (‘Wis. 639’, ‘Merrimack’, and ‘Superior’) and 3 diploid (2n = 2x = 24) Phureja-haploid hybrids (W5293.3, W5295.7, and W5845.1), significantly higher tuber yields were obtained in 1970 in families only when the 2x clone W5295.7 was the female parent. The differences in yield in the progeny of these reciprocal crosses were attributed to the mode of 2n gamete formation, since of the 2x clones used, only W5295.7 forms diplandrous gametes by first division restitution. In 1971 with the same materials at 2 locations, significantly higher tuber yields were obtained only in the progeny of 4x × 2x crosses with W5295.7 as the pollen source. These results agree with the hypothesis that the method of diplandroid (2n pollen) formation is responsible for differences in yields of the progeny from reciprocal crosses. Data agreeing with this hypothesis resulted from reciprocal crosses involving four 4x cultivars (‘Kennebec’, ‘Katahdin’, ‘Platte’, and ‘Wis 231’) and two 2x clones (W5295.7 and W5293.3). The progeny from these reciprocal crosses were tested for yield in 1971 and 1972. Differences in yield from progeny of reciprocal crosses again were obtained only with the 2x clone W5295.7 which forms diplandroids by first division restitution.

Characterization of a conditional mutant of Rous sarcoma virus with alterations in early and late functions of cell transformation

Mutants were isolated from γ-irradiated stocks of Schmidt-Ruppin Rous sarcoma virus (SR-RSV-2). One isolate, MI-100, displayed unusual properties in its temperature sensitivity of cell-transforming capabilities. Focus formation, colony formation in soft agar, and increased [ 3H]deoxyglucose uptake by infected cells were all rendered temperature sensitive ( ts); 37° was permissive for expression of these functions while 41° was nonpermissive. Tumorigenicity in chickens was greatly diminished. Virus replication was not defective since virus yields exceeded those of wild-type RSV at 37 and 41°. Yields of infectious progeny may have been higher than shown by titrations, as virions of MI-100 were more heat labile than wild type. Group-specific antigen concentrations in MI-100 infected were almost equivalent at 37 and 41° and greater at both temperatures than those of wild-type-infected cells. Through genetic recombination with Rous-associated virus (RAV-1), subgroup specificity of MI-100 was altered from B to A without correcting the temperature sensitivity of transformation. However, temperature-shift experiments demonstrated a major difference in the ts properties of the mutant and its recombinant. MI-100 was unable to transform cells at 37° if initial incubation after infection was at 41° (irreversible inhibition); also, shifts of infected cells, at any time, from 37 to 41° resulted in loss of the transformed phenotype (reversible inhibition). Cells infected with the recombinant still required permissive temperature in order to express the transformed phenotype, but initial incubation at 41° after infection did not affect the ability to transform cells at 37°. Thus there appeared to be ts lesions in MI-100 affecting transformation, one in an early function and one related to a late function. Recombination with RAV-1 restored the early but not the late functions, suggesting that leukosis viruses possess a gene coding for some initial event in fibroblast transformation but lack the gene(s) required for full expression (maintenance) of the transformed state. Moreover, as shown by the replicative properties of the mutant, the early gene of transformation initiation is apparently not involved in virus replication.

Postemergence Effects of Two Insect Growth Regulators on the Mosquito Culex Tarsalis (Diptera: Culicidae)

After treating 4th-instar larvae of Culex tarsalis Coquillett at 0.1 and 1 ppb of Altosid™ [Isopropyl (2E,4E)-11-methoxy-3,7,11,-trimethyl-2,4-dodecadienoate] and 0.1 and 0.4 ppb of TH-6040 [1-(4-chlorophenyl)-3(2,6-difluorobenzoyl) urea], the adult mortality, fecundity, and egg viability of the resulting adults were assessed and compared with the checks. There was no significant difference in mortality of adults resulting from any of the treatments and that of checks except in the 0.4 ppb TH-6040 treatment where postemergence adult mortality was significantly greater than that in the checks and the other treatments. Adults resulting from 4th-instar larvae treated at 0.4 ppb of TH-6040 produced 43% fewer eggs/female than did the controls, but the greater adult mortality from this concentration was the main reason for this occurrence. When the number of eggs/female-day was calculated, it was found that adults resulting from the 0.4 ppb TH-6040-treated population did not produce fewer eggs/female-day than the controls. However, a 25% reduction in number of eggs/female-day was noted in the 1.0 ppb Altosid treatment relative to the untreated females. As a whole there was a 5% and 14% reduction in number of egg rafts resulting from the 0.1 and 1 ppb Altosid treatments, respectively. There was also a 12% increase and a 40% decrease in number of egg rafts in the 0.1 and 0.4 ppb TH-6040 treatments, respectively. Egg viability was affected at the higher rate (1 ppb) of Altosid, where 30% reduction was obtained. Mosquitoes treated with 0.1 ppb Altosid, 0.1 and 0.4 ppb TH-6040 showed no appreciable difference in percentage of egg hatch. The yield of progeny of adults from the higher rates of both insect growth regulators was depressed in the order of 36–38% in the treatments, as compared to the progeny in the control populations.

YIELD PERFORMANCE OF EIGHT WHEAT CULTIVARS IN TWO- AND THREE-ROW PLOTS

Yield performance of eight wheat cultivars (Triticum aestivum L.) was compared in two-row plots with 38 cm between rows and in three-row plots with 19 cm between rows. The cultivar × row spacing interaction was nonsignificant in each of four tests. The range of cultivar yield from two-row plots as a percentage of the mean was similar to that for cultivar yield from three-row plots. Duncan’s multiple range test was applied to yield of cultivars grown in two-row and three-row plots. The grouping of cultivar yield from two-row plots was very similar to the grouping of cultivar yield from three-row plots. The standard error of a mean and coefficient of variation were consistently lower for three-row plots than for two-row plots. The relationship between yield performance of a line in two-row plots and three-row plots was positive, such that two-row plots would be suitable for early generation progeny yield tests with final evaluation in multiple-row plots.

Studies on Intra‐ and Inter‐Specific Competition in Drosophila

Of eight species of Drosophila (ananassae, funebris, melanogaster, nebulosa, pseudobscura, simulans, virilis, and willistoni), the number of progeny produced per culture vial increases with the number of female parents for D. melanogaster, D. simulans, D. willistoni, D. ananassae, and D. nebulosa; in contrast, the progeny yield is a constant that is independent of the number of parental females per vial for D. funebris, D. pseudoobscura, and D. virilis. Forall species, however, the per capita yield decreases more or less exponentially with the square—root of the number of parental females per vial. The outcome of mixed—species competition depends largely upon the two species concerned. Drosophila simulans seemingly benefits by increases in number of its own females; four or five D. simulans females yield more progeny in the presence of D. funebris, for example, than produces D. simulans. Drosophila simulans alsoproduces greater number of progeny per vial as the number of competing D. funebris females is increased. Drosophila melanogaster and D. simulans females competing in individual culturesyield mixed progeny; the two species share the resources of each vial. In contrast, the progeny of D. pseudoobscura and D. virilis females in individual mixed—culture vials tend to be of one species or the other many cultures containing these two types of females yield few or no flies of either species. For most species—pairs the logarithm of the ratio of the two species among offspring varies directly with that among parents (slope of the regression = 1.00). For three species—pairs, however, the slope of this regression is significantly less than 1.00. If the same relationship were to hold among freelybreeding populations of the two species, the species should establish stable equilibrium proportions. Analyses of the competing species by means of replacement series reveals that the members of individual pairs may enhance or interfere with each other's development, or do neither. Similarly, the competitive abilities of the species differ considerably. The ease with which each species uses different resources within the culture vials differs. Thus, intra— and interspecific competition differentially affect the per capita progeny production of conspecific and heterospecific females. Because the competition between conspecific females differs demonstrably from that between heterospecific ones, it appears that inter—specific frequency—dependent selection may reflect the relative proportions of resources that are used with contrasting ease by the competing species. If so, frequency—dependent selection is precisely the sort of evidence needed to demonstrate that two species are not competing identically for identical resources, the type of competition that is expected to lead to competitive exclusion.

Comparison of S1 and Testcross Evaluation after Two Cycles of Recurrent Selection in Maize1

Two populations of maize (Zea mays L.), Virginia Corn Belt‐Southern Synthetic (VCBS) which was developed from a broad genetic base, and Virginia Long Ear Synthetic (VLE) which was developed from intercrosses of seven Corn Belt inbred lines, were advanced two cycles of recurrent selection based on S1 and testcross progeny yield. The 10 populations and their diallel crosses were grown at 3 locations with 6 replications at each location. Significant improvement in population yield and combining ability was achieved only with VCBS.S1 selection in VCBS was more effective than testcross selection in increasing both population yield and combining ability. Testcross selection was effective in increasing the frequency of genes that contribute to yield in crosses but not in populations per se whereas S1 selection increased both combining ability and population yield. The yield of the second‐cycle S1 selection population yielded 9.0 q/ha (11%) more than the second‐cycle testcross population and its mean population cross yield was 1.5 q/ha higher. The two populations derived from VCBS by S1 selection produced significantly higher yields when intercrossed or crossed with VCBS than either population derived by testcross selection. S1 selection in VCBS was as effective as testcross selection in increasing the frequencies of genes that contribute to yield, whether in inbred (derived) or hybrid populations.

Defective interfering particles of poliovirus. 3. Interference and enrichment.

Interference with standard poliovirus growth resulting from co-infection of cells with standard virus and defective interfering particles has been investigated. At all time following infection, co-infected cells produced less standard progeny than cells infected only by standard virus. The total yield of physical particles and the percentage of standard virus among these particles was a linear function of the percentage of standard virus in the inoculum. The actual yield of standard virus thus varied as the square of the percentage of standard virus in the inoculum. The extent of interference could also be controlled by varying the time interval between initial infection of cells by one type of particle and superinfection by the other. Identical amounts of viral RNA and virus-specific polyribosomes are formed in co-infected or singly infected cells. Interference apparently results from the partitioning of these limited synthetic capacities between standard and defective interfering-specific RNA and protein synthesis. Standard and DI RNA appear to serve equally well as messenger RNAs because standard and DI-specific viral proteins are synthesized in ratios proportional to the ratio of standard to DI particles in the inoculum. Only standard RNA can direct the formation of capsid protein, so co-infected cells contain reduced amounts of the virion protein precursor, the procapsid. Standard and DI RNA are encapsidated with approximately equal efficiency. Thus interference results from equal participation in the intracellular events of the infection cycle by both types of particles. The progeny yield from co-infected cells was always enriched about 5 to 8% in DI particles. Progeny were produced in the enriched ratio throughout the infection cycle.

Intra-varietal variability and response to single plant selection in Gossypium hirsutum L.: III. Response to selection

SummaryResponse to selection primarily for lint yield among spaced plant populations of four American and one African variety of Gossypium hirsutum L., established in 1965—6 at Kimberley Research Station, was studied in three experiments conducted between 1966 and 1970.In the first experiment, in which single-hill micro-plots of 3–5 plants per hill were used, the mean lint yield of progenies was larger than predicted from single plant heritabilities. In the second experiment, in which single-row plots were used, response to selection for lint yield was generally less than expected. In the third experiment, in which three-row plots were used, response to selection for lint yield was again less than expected and less than manifested in the second experiment. However, in all experiments responses to selection for lint percentage, lint quality properties, and height were close to expectations while some individual progenies substantially out-yielded their unselected parents.The progressive decline in response to selection for lint yield from the first to thethird experiment, and the discrepancies between the actual responses and the expected responses for lint yield in all experiments, were interpreted mainly on a basis of intergenotypic competitive effects differing in sympathy with plot size and plant disposition.It was concluded that the objective methods of selection practised were successful when judged on plant breeding criteria. It was also concluded that intra-varietal selection is an important technique by which genetic improvement can be achieved at regional breeding centres with limited resources.

Abortive infection of Japanese quail cells with avian sarcoma viruses

The replication of Prague strains of Rous sarcoma virus (PR RSV) and avian sarcoma virus B77 in Japanese quail cells is abortive in a quantitative sense. Although efficient infection of quail cells, as evidenced by transformation, was obtained with these viruses, the yield of progeny was suppressed by 10 2-fold or more relative to the chick cell host, and for many clones of transformed quail cells tested, no yield could be detected. Infectious center assays, however, indicated that each transformed cell produces a small yield of progeny. The yield of progeny can be enhanced by prior infection of quail cells with avian leukosis viruses or rescued by superinfection with avian sarcoma viruses inoculated at higher multiplicity than the initial infecting virus. B77-transformed, abortively infected quail cells synthesize viral envelope proteins as evidenced by the complementation of the defective Bryan high titer strain of Rous sarcoma virus (BH RSV); the dominant progeny species of such complementation is, however, genotypically BH RSV. The possibility that the replication of the B77 genome in quail cells is inefficient is suggested.

Comparison of S1 and Open‐Pollination Progenies of Astragalus cicer L. for Certain Agronomic Characters1

Self‐ (S1) and open‐pollination (O.P.) progenies of 24 self‐compatible S0 plants of cicer milkvetch (Astragalus cicer L.) were evaluated in the field for forage yield, height, spread, vigor score, and date of flowering. One generation of inbreeding had such a deleterious effect on plant vigor that paired S1 and O.P. progenies could be differentiated visually. Forage yields of the S1 progenies were approximately 50% of the forage yields of O.P. progenies. Considerable variation occurred among S0 plants for inbreeding depression. Inbreeding delayed flowering approximately 10 days in the seedling year, but there was little difference between the S1 and O.P. progenies for mean date of flowering in subsequent growth periods. There was no relationship between the self‐compatibility of the S0 parents and forage yields of their S1 and O.P. progenies.There were significant differences among S0 parents for general combining ability. Open‐pollination progenies of several S0 plants with average vigor performed better than similar progenies of S0 plants with excellent vigor.Simple correlation coefficients between forage yield, height, spread, vigor score, and date of flowering were highly significant. The associations between vigor score and forage yield were the highest with coefficients of —0.93, —0.91, and —0.92 for the one harvest in 1970 and the first and second harvests in 1971, respectively.

UV-induced recombination and repair of parental lambda bacteriophages labeled by means of host-controlled modification

The UV-enhancement of λ bacteriophage recombination has been examined utilizing parental phages labeled by means of host-controlled modification. Light UV - irradiation of λ phages infecting HCR + or HCR − Escherichia coli bacteria causes similar absolute increases in the frequencies of recombinants among all progeny phages and among progeny that contain HCM-labeled—λ · K12(P1)—parental DNA strands. The UV-induced recombination involves breakage and reunion of parental DNA strands. With increasing UV dose to the infecting phages there is a decrease in the relative yield of progeny that retain a parental HCM label. The HCM-labeled λ progeny recovered from multiple infections with UV-irradiated phages of excision-defective HCR −, but not HCR +, bacteria contain nearly as many host-cell reactivable UV lesions as the infecting phages; these HCM-labeled progeny probably contain mainly conserved parental DNA. The possibility that there may be a selection against recovery of semiconserved parental DNA from infections with UV-irradiated phages is discussed. UV-induced recombinants may be formed prior to replication of the infecting phage DNA.

Maturation of infectious simian virus 40 in the presence of ethidium bromide.

SUMMARY We have investigated the effect of ethidium bromide (EB) on synthesis of nuclear, virus and mitochondrial DNA in permissive cells infected with simian virus 40 (SV 40). In the presence of EB, no newly formed, closed-circular, mitochondrial DNA (M-DNA) could be detected by isopycnic EB-CsCl gradient centrifugation. Synthesis of nuclear and virus DNA was not inhibited by a concentration of 8 µg./ml., even though SV40-DNA and M-DNA are similar in their tertiary structure, in that both are supercoiled, closed-circular, double-stranded molecules. The yield of SV40 progeny under these conditions was not reduced nor was their specific infectivity affected, as compared to control values.

EVALUATION OF NINE OAT VARIETIES AS PARENTS IN BREEDING FOR SHORT STOUT STRAW WITH HIGH GRAIN YIELD USING F1, F2, AND F3 BULKED PROGENIES

Twenty-one oat hybrids from Stormont, Kelsey, and Dorval crossed with each other and with Tyler, Goodfield, Egdolon-26, Orbit, O.A. 123-91, and P.I. 193027 were evaluated in F2 and F3 field trials using index selection. Desired goals for plant height, stem diameter, 1000 kernel weight, and grain yield were defined in terms of lodging-resistance components similar to those of Stormont but with higher yield. Stormont × Orbit was the outstanding cross. General combining ability effects showed that the outstanding parents were Egdolon and Stormont for short stout stems, and Orbit for 1000 kernel weight and yield. Data from F1 spaced plants growing in an optimum environment was of no value for predicting F2 and F3 field performance. Midparent values, calculated from parents included in the field trials, were good predictors for stem dimensions and 1000 kernel weight, but were only fair predictors of progeny yields.

Effect of Seed Source on Seedling Vigor, Yield, and Lint Characteristics of Upland Cotton, Gossypmm hirsutum L.1

Seed of ‘Empire WR 61’ and ‘Coker 100A WR’ Upland cotton (Gossypium hirsutum L.) from a common source were selfed or grown in isolated blocks for one generation at nine locations (sources). These seed were subsequently planted at Experiment, Georgia, in 1965 and 1966. Lint yield and seedling vigor data indicated that differences in progeny performance each year, and for both years combined, were associated with seed source. Seed source did not affect lint percent, seed index, boll size, fiber length, fiber strength, and fiber fineness either year. Correlations between progeny yield and vigor rating (r = 0.988 in 1965, r = 0.977 in 1966, and r = 0.988 for the combined data) were highly significant (P≤.Ol) indicating that vigor ratings were good indicators of progeny performance. Correlations between progeny yield and September minimum temperature at seed source (r = _0.519 in 1965, r = _0.553 in 1966, and r = _0.540 for the combined data), and between progeny yield and August rainfall at seed source (r = 0.524 in 1965, r = 0.535 in 1966, and r = 0.532 for the combined data) were significant (P≤.05) and each accounted for about 27% of the variability among seed sources. Higher temperatures and lower rainfall were associated with lower yield and poorer seedling vigor.

The phenology of skin spot (Oospora pustulans Owen &Wakef.) and other fungal diseases of potato tubers

SUMMARYUnderground stems and roots of the potato varieties King Edward and Majestic became more severely infected by Oospora pustulans (skin spot) as the growing season advanced. Tubers became infected at their initiation in June and July but the proportion of infected eyes usually increased during both the growth of the crop and bulk storage. Some buds on tubers in bulk stores died in December, but few were killed until after January, when attacks increased until by March about a quarter of Majestic eyes were usually dead. Boxing (chitting) not only prevented most eyes from dying but also prevented much skin spotting on tubers. At High Mowthorpe, Majestic seed unboxed or boxed in March yielded, respectively, 3 and 1 ton/acre less than seed boxed by January. Early boxing increased the yield of seed–sized tubers but did not affect the infection of progeny tubers. Dipping Majestic seed tubers in organo–mercurial fungicide and then boxing soon after lifting decreased their infection by O. pustulans; it also lessened infection on plants they produced and increased the yield of progeny seed–sized tubers. However, dipping, even in successive years, had little effect on the infection of progeny tubers by O. pustulans. Rhizoctonia solani and Helminihosporum atrovirens became increasingly prevalent on tubers during growth after July and during bulk storage. H. atrovirens was decreased by early boxing or dipping tubers in fungicide. Verticillate conidiophores often grew on incubated tuber plugs but their prevalence was affected by past storage.The results suggest that some of the benefit for chitting may be from disease control, it was not possible to measure the extent to which benefits from chitting depend on effects on disease or on the physiology of the tuber.

Comparison of Selection Based on Yield of Topcross Progenies and of S2 Progenies in Maize (Zea mays L.)1

Three methods of breeding for higher grain yield in maize (Zea mays L.) were compared: (a) recurrent selection for combining ability with the parental population (Parental Tester method), (b) recurrent selection for combining ability with an unrelated inbred line (Inbred Tester method), and (c) recurrent selection for yield of S2 progenies per se (S2 Progeny method).After three cycles of selection for grain yield had been completed with each of the three methods, the nine resulting selected populations were evaluated for grain yield (a) as random‐mated populations (synthetics), (b) as selfed populations (bulked S1 lines), and (c) in crosses with 11 unrelated testers. Significant differences among the breeding methods were noted for the second and third cycles of selection, but not for the first cycle. The Parental Tester method produced the highest yielding random‐mated (syn‐3) population; whereas the S2 Progeny method produced the highest yielding selfed population. Average combining ability with unrelated testers for all three methods was increased significantly (5.2%) by the second and third cycles of selection, but there was no significant difference among methods. Although the Inbred Tester method resulted in significant improvement in yield of selfed populations, it was inferior to the other two methods for population improvement in the over‐all evaluation.Selfing one generation resulted in over 70% reduction in yield of the first cycle populations, which indicates that dominance is of considerable importance in the base population. Inbreeding depression was progressively less drastic in the second and third cycle populations, particularly with the S2 Progeny method.

Developmental inhibition in Drosophila using dihydroxybenzoic acid isomers

Five isomers of dihydroxybenzoic acid were added to a standard culture medium of Drosophila melanogaster and their effect on development time and progeny yield examined. Each isomer produced a distinct level of inhibitive influence throughout continuous inbred generations. The degree of developmental perturbation from a particular isomer was dependent on its protondonating power. Details of the alterations indicated enzyme inhibitions associated with the reaction kinetics of oxidative processes. A simple withdrawal of oxygen by briefly submerging pupae in water also altered the ontogenetic cycle suggesting an analogue of the isomer effect. Lengthened development produced by oxygen withdrawal in first-generation pupae was transferred to succeeding inbred generations. Published pharmacological studies in which drugs were introduced into Drosophila medium are given an interpretation based on the findings with the dihydroxybenzoic acid isomers.

Biochemical studies on influenza virus multiplication at reduced temperatures.

Summary At 25° all components of fowl plague virus were synthesized in chick embryo fibroblasts. The rate of formation was about a quarter of that at 37°, but the final yield was the same. Infectious virus, however, was not formed at 25°. If infected cells were preincubated at 25° for 20 hr and thereafter kept at 37°, a normal yield of infectious progeny was found. With longer preincubation at 25° a decreasing yield of infectious virus was found. This effect may have been due to the synthesis at 25° of a viral component responsible for the cytopathic effect which acts only at the higher temperature. Preincubation of infected cells at 37° for different times and further incubation at 25° revealed a virus-specific precursor synthesized early in the infectious cycle which was rate limiting at 25°.

Polycross‐Progeny Testing of Red Clover (trifolium pratense L.1

Investigations were conducted into the feasibility of breeding red clover (Trifolium pratense L.) for persistence utilizing polycross‐progeny testing. Approximately 1,500 clones of red clover were vegetatively increased and selected for virus tolerance in nurseries. Ultimately, 20 clones were selected for polycross progeny testing. Seed produced on the 20 clones under conditions of random pollination were sown at two locations. Persistence of clones was correlated with persistence of progenies, but the value of progeny testing was indicated because only a portion of the variability in persistence could be recognized by clonal evaluation alone. Yields of progenies were greatly different only in the 3rd year at which time persistence was expressed. Earliness of bloom of the first growth was implicated in previous and in the present research as being associated with lack of persistence. No correlation existed between earliness of the first crop with that of the second crop. Earliness of the first growth was transmitted to progenies but because of the practice of harvesting seed from the second‐crop growth, selection for earlinesss was eliminated in these genetic materials. Use of the polycross test in the breeding of red clover for persistence appears to have been effective in view of the genetic gain made in the selected materials. Further gains should be possible when the most persistent of the 20 clones are combined into a synthetic variety.