F2 Selection Research Articles

‘Mountain Majesty’: A Tomato Spotted Wilt Virus-resistant Fresh-market Hybrid Tomato and Its Parents NC 714 and NC 1CS

‘Mountain Majesty’, the F1 hybrid of NC 714·NC 1CS (Fig. 1), resulted from a tomato breeding effort to develop a superior largefruited hybrid tomato with improved fruit color based on the crimson (og) gene combined with fusarium wilt, verticillium wilt, and TSWV resistances adapted to vine-ripe production in North Carolina (NC). NC 714 resulted from selfing NC 03113, the F1 hybrid of Fla 8044 · NC 00318–15(x)-1 (Fig. 1). Fla 8044 is a large-fruited, hightemperature fruit set line with desirable horticultural traits and multiple disease resistance genes obtained from the University of Florida tomato breeding program. NC 00318–15(x)-1 is an F2 selection obtained by crossing a male sterile version of NC 84173 with an F3 generation line derived from selfing the North Carolina State University (NCSU)-released hybrid ‘Mountain Crest’ (NC 84173 · NC 1 rinEC) (Gardner, 2006). The crimson gene in NC 714 was derived from the NC 1rinEC parent of ‘Mountain Crest’ and Fla 8044. The objective of breeding NC 714 was to incorporate desirable fruit characteristics and superior combining ability from NC 84173 (Gardner, 1992) together with the crimson gene for increased red fruit color and lycopene content. Single plant selections were made for large fruit size, high yield, and other desirable horticultural traits in the F2 through F5 generations derived from selfing NC 03113. NC 1 CS resulted from selfing NC 056, the F1 hybrid of NC 123S ·NC 0255(x)-1 (Fig. 1). NC 123S, which combines single dominant gene resistances to TSWV, fusarium wilt race 3, and nematodes (Sw-5, I-3, Mi genes) and was released from the NC breeding program. ‘Amelia’ F1 hybrid, from which NC 123S was developed, is a codeveloped hybrid using NC 111F-2(98) as a source of the I-3 gene for fusarium wilt race 3 resistance crossed with a Clause Seed Company proprietary line having the Sw-5 and Mi genes. NC 0255(x)-1 is an outstanding large-fruited selection with the crimson gene that traces its pedigree back to breeding lines and cultivars developed in the NC tomato breeding program over a 25year period (Fig. 1). The source of the crimson gene in NC 0255(x)-1 is ‘Suncoast’, an inbred cultivar released from the University of Florida breeding program.

Selection for Phytophthora field resistance in the F2 generation of organic outdoor tomatoes

Tomatoes are the most important vegeta- ble, globally as well as in Germany. Outdoor tomato production is seriously impaired due to increasing infections with evolving late blight (Phytophthora infestans) populations. Within organic agriculture, research is being conducted to develop regionally adapted and open pollinated cultivars of outdoor tomatoes with late blight field resistance. In the present experiment, three crosses, including wild, cocktail, and beefsteak tomatoes, were selected for field resistance against late blight in F2 at one location per cross. The comparison of positive and negative selection in F3 revealed the selection of single F2 plants to be efficient in all three crosses. F2 selection has proved to be a robust and efficient tool for breeding programs. The correlated response to selection in other traits, including yield, fruit weight, days to maturity, harvest period, and plant height, depended on the cross. It was evident that selection for desired traits combined with field resistance against late blight is promising, even in wide crosses. The most undesired attribute of wild tomatoes is the formation of shoots on leaves and in inflorescences. No correlation was observed between field resistance and shoot formation, allowing the selection of genotypes with improved field resistance and yield, but without morphological disadvantages.

Influence of environmental and genetic factors on health-related compounds in strawberry

Strawberry ( Fragaria × ananassa, Duch.) represents a relevant source of micronutrients and phenolic substances, most of which are natural antioxidants and contribute to the high nutritional quality (NQ) of the fruit. Despite its proven health benefits, strawberries also contain allergenic compounds. In particular protein Fra a 1 is considered the main cause of allergic reactions after consumption of these fruits. However, there is a dearth of literature data on the genetic and seasonal influences on the Fra a 1 accumulation in strawberries, and on the quantitative variation of this allergen during fruit ripening. The aim of the present study was to evaluate and compare the total antioxidant capacity and vitamin C, phenolic, protein and allergen contents of four strawberry genotypes. Two commercial varieties, “Adria” and “Sveva”, and two advanced selections originating from the Marche Polytechnic University strawberry breeding program, “AN94.414.52” and “AN00.239.55”, were selected for this study. To assess the genotype and seasonal influence on the strawberry nutritional and non-nutritional traits, strawberries in three different ripening stages were analysed during the fruiting seasons 2007 and 2008. In the 2-year evaluation, the ripe red fruits of the cultivar “Sveva” showed the highest TAC, phenolic and flavonoid contents and interestingly the lowest allergen content. However, the variety “Sveva”, together with the F2 selection “AN00.239.55”, were the most affected by the year-to-year variability of temperature observed in the nutritional and non-nutritional aspects of the fruits. These findings confirmed a relevant genotype-dependent response to environmental stress conditions, which may in part explain the changes in the antioxidant, phenolic and allergenic properties of strawberry fruits in different years.

Association between advanced generations and genealogy in inbred lines of snap bean by the Ward-Modified Location Model

The Ward-MLM strategy first proposed by Franco et al. (Crop Sci 38:1688–1696, 1998) is a useful method for analyzing genetic divergence for genealogical comparisons. However, this method has not yet been applied in conjunction with early generation testing (EGT) and single seed descent (SSD) procedures in autogamous plant species bred to advanced generations. In this study, we quantified the diversity of 120 recombinant snap bean lines from the F6:7 generation, advanced by SSD from the application of EGT in F2, to investigate the association between the grouping of lines and genealogy using the Ward-MLM method. Four F2 populations with high pod yields were selected from crosses among five genotypes. The segregating population was advanced to F6:7 by the SSD method. The traits of plant height, mean pod length, number of seeds per pod, mean number of days to flowering, mean pod fiber content and pod yield were evaluated. Based on the distribution of lines in the groups by the Ward-MLM approach, variability was verified in the four populations. Furthermore, the early selection in F2 did not limit the variability in the expression of genotypes with better agronomic performance. Thirty lines advanced by SSD for each population studied were sufficient to obtain superior genotypes. There was a relationship between the genealogy and groupings in F6:7, as evidenced by Group 1, G1, which contained the greatest number of lines from the crossing that were significantly enriched for their mean pod yield and Group 3, G3, which comprised the highest number of lines with a shorter plant type. These two traits, respectively, are the first and second most important traits for group stratification.

Interspecific hybridisation and genome size analysis in Buddleja

Interspecific hybrids Buddlejadavidii × Buddlejaweyeriana, Buddlejaweyeriana × Buddlejadavidii and Buddlejadavidii × Buddlejalindleyana were generated using in vitro embryo rescue 10–11 weeks after manual pollination. The morphological variation within the F1 populations was limited. The F1 progeny of B. davidii × B. lindleyana was almost sterile and no F2 generation was obtained. From the other hybrids, F2 generations were made by self pollinations and back crosses. Hybrid nature of all F1 and F2 seedlings was confirmed by AFLP. Chromosome counting and genome size measurement for B. weyeriana (F2 selection of (diploid) B. globosa × (tetraploid) B. davidii) revealed a higher chromosome number (76 chromosomes) and genome size than expected, indicating 2n-gametes formation occurred during meiosis of B. globosa. The F1 hybrids B. weyeriana × B. davidii (76 chromosomes) had an intermediate genome size compared with the genome size of the parent plants, proving their hybrid nature. However, the F1 and F2 hybrids of B. davidii × B. weyeriana all had 76 chromosomes but had a lower genome size than expected, suggesting the occurrence of chromosome rearrangements in the genome of the hybrids. B. lindleyana had 38 chromosomes, while the F1 hybrids of B. davidii × B. lindleyana had 76 chromosomes. Also genome size measurements revealed that the F1 seedlings B. davidii × B. lindleyana had higher genome sizes than expected. Both the results of chromosome counting and genome size measurement indicate that 2n-gametes formation took place during meiosis of B. lindleyana.

RECURRENT SELECTION FOR LINT YIELD AND ITS COMPONENTS OF SOME EGYPTIAN COTTON GENOTYPES

All possible mating among four F2 selections of the highest lint percentage and four F2 selections of the highest seed index were made for three populations (G. 45 x G. 75 (I), G. 87 x G. 89 (II) and G. 86 (III) grown from open-pollinated bulks for four years) to produce desirable recombinations. The 28-hybrids resulted from each population gave the highest means of lint yield/plant, bolls/plant and seeds/boll compared with the means of the better parent for populations I and II. In addition, the 28 hybrids means performance were higher than Giza 86 pure line mean for lint/seed, lint percentage and seed index in population III. The highest predicted genetic advance was achieved for lint yield/plant, bolls/plant, lint/seed and seed index in the three populations. High to low genetic advances were found to associated with high to low values of GCA most studied characters in the three populations.

Herdabilidade dos teores de fibra alimentar e rendimento de grãos em populações de feijoeiro

O objetivo deste trabalho foi determinar a herdabilidade e o ganho na seleção para teor de fibra alimentar (solúvel, insolúvel e total) e para rendimento de grãos, em populações resultantes de cinco diferentes cruzamentos, além de identificar a população mais adequada, considerando-se as diferentes frações da fibra. Os cruzamentos entre os genitores CNFP 8100, FT 96-1282, Varre-Sai e Valente foram realizados em casa de vegetação. As populações obtidas (genitores, F1 e F2) foram avaliadas em campo, durante a primavera/verão de 2003/2004, em delineamento de blocos ao acaso. Diferenças significativas foram obtidas para fibra alimentar total; não foi detectada variabilidade genética para as frações da fibra - solúvel e insolúvel - e para rendimento de grãos nas populações. Correlação fenotípica positiva foi encontrada entre fibra insolúvel e fibra alimentar total. A seleção de plantas F2, em populações segregantes desenvolvidas a partir da combinação Valente x Varre-Sai, pode ser efetiva no desenvolvimento de germoplasma de feijão com maior teor de fibra alimentar total, em virtude da alta herdabilidade e maior ganho por seleção obtidos.

Resistance to Plum Pox Virus (Dideron Isolate RB3.30) in a Group of California Almonds and Transfer of Resistance to Peach

Sharka [(plum pox virus (PPV)] mainly affects Prunus species, including apricot (Prunus armeniaca L.), peach (Prunus persica L.), plum (Prunus salicina Lindl., Prunus domestica L.), and, to a lesser degree, sweet (Prunus avium L.) and sour cherry (Prunus cerasus L.). Level of resistance to a Dideron isolate of PPV in seven California almond [P. dulcis (Miller) D.A. Webb], five processing peach cultivars, and two peach rootstocks was evaluated. In addition, almond and peach selections resulting from interspecific almond × peach hybridization and subsequent gene introgression were tested. Evaluations were conducted in controlled facilities after grafting the test genotypes onto inoculated GF305 peach rootstocks. Leaves were evaluated for PPV symptoms during three consecutive cycles of growth. ELISA-DASI and RT-PCR analysis were also employed to verify the presence or absence of PPV. Peach cultivars and rootstocks showed sharka symptoms and were ELISA-DASI or RT-PCR positive for some growth cycles, indicating their susceptibility to PPV. Almond cultivars and almond × peach hybrids did not show symptoms and were ELISA-DASI and RT-PCR negative, demonstrating resistance to PPV. Two (almond × peach) F2 selections as well as two of three backcrossed peach selections also showed a resistant behavior against the PPV-D isolate. Results demonstrate a high level of resistance in almond and indicate potential for PPV resistance transfer to commercial peach cultivars.

Tomato Bacterial Spot Resistance Derived from PI 114490; Inheritance of Resistance to Race T2 and Relationship across Three Pathogen Races

Crosses were made between tomato (Lycopersicon esculentum Mill.) inbreds susceptible to races T2 and T3 of bacterial spot (Xanthomonas vesicatoria and Xanthomonas campestris pv. vesicatoria, respectively) and accession PI 114490 with resistance to races T1, T2, and T3. Resistance to race T2 was analyzed using the parents, F1, and F2 generations from one of the crosses. The F1 was intermediate between the parents for disease severity suggesting additive gene action. The segregation of F2 progeny fit a two-locus model (χ2 = 0.96, P = 0.9-0.5) where four resistance alleles are required for a high resistance level, two or three resistance alleles provide intermediate resistance, and zero or one resistance allele results in susceptibility. The narrow sense heritability of resistance to T2 strains was estimated to be 0.37 ± 0.1 based on F2 to F3 parent-offspring regression. A second cross was developed into an inbred backcross (IBC) population to facilitate multilocation replicated testing with multiple races. Segregation for T2 resistance in the inbred backcross population also suggested control was by two loci, lending support to the two-locus model hypothesized based on the F2 segregation. To determine if the same loci conferred resistance to the other races, selections for race T2 resistance were made in the F2 and F3 generations and for race T3 resistance in the F2 through F4 generations. Six T3 selections (F5), 13 T2 selections (F4's that diverged from seven F2 selections), and control lines were then evaluated for disease severity to races T1, T2, and T3 over two seasons. Linear correlations were used to estimate the efficiency of selecting for resistance to multiple races based on a disease nursery inoculated with a single race. Race T1 and race T2 disease severities were correlated (r ≥ 0.80, P< 0.001) within and between years while neither was correlated to race T3 either year. These results suggest that selecting for race T2 resistance in progeny derived from crosses to PI 114490 would be an effective strategy to obtain resistance to both race T1 and T2 in the populations tested. In contrast, selection for race T3 or T2 will be less likely to result in lines with resistance to the other race. PI 114490 had less resistance to T3 than to T2 or T1. Independent segregation of T2 and T3 resistance from the IBC population derived from PI 114490 suggests that T3 resistance is not controlled by the same genes as T2 resistance, supporting the linear correlation data.

Inheritance of Scarlet Color and Vein Pattern in Flowers and Oxblood Red Seedcoat Color Derived from the Interspecific Cross of Common Bean with Scarlet Runner Bean (Phaseolus coccineus L.)

The genetics of the vermilion flower color (more orange than scarlet or salmon red) of Phaseolus coccineus L. is largely unknown, but the gene Sal for salmon red is the gene essential for its expression. Lamprecht line M0169 (PI 527868) expresses salmon red flowers with vein pattern on the wing petals and black seedcoats. M0169 (Sal Am and an unknown gene that inhibits the scarlet flower color expression of Am) was crossed with v BC3 5-593 (sal am and no inhibitor gene, expressing white flowers and mineral brown seedcoats). Line 5-593 is a Florida dry bean (Phaseolus vulgaris L.) line used as the recurrent parent for development of genetic stocks. The F2 from Sal Am Vwf BC1 5-593 (scarlet flowers, black seedcoats) × v BC3 5-593 (white flowers, mineral brown seedcoats) supported the hypothesis that a partly dominant gene Am changes salmon red to scarlet flower color and that Am has no expression with sal. The F3 progeny test of 27 random F2 parents from the above cross supported the hypothesis of a single partly dominant factor (Am) with no expression without Sal, where only Sal/Sal Am/Am completely eliminates the flower vein pattern (VP) of Sal. F4 progeny tests of 29 random F3 parents derived from a F2 selection with Sal/Sal Am/am Vwf/v supported the hypothesis that Am is linked to V (cM = 9.4 ± 1.93) and the hypothesis that Am is linked with a dominant gene (tentative symbol Oxb) that (with Sal v) changes seedcoat color from mineral brown with red haze to oxblood red. Another F4 progeny test of seven selected F3 parents with Sal/Sal Am/am v/v and oxblood seedcoat color supported the hypothesis that the Oxb gene (linked with Am and derived from M0169) with Sal v expresses oxblood seedcoat color. The gene symbol Am is proposed for the gene from M0169 that with Sal v expresses two pleiotropic effects: changes salmon red to scarlet flower color and eliminates the VP of salmon red. The interaction of Sal with Am for flower color and VP expression is discussed for all gene combinations.

080 Postharvest Longevity Analysis of Advance Generations in Antirrhinum majus L.

Cut flowers of Antirrhinum majus L. (snapdragon) P1, P2, F1, F3, and F2 × F2 plants were harvested after the first five flowers were open and were evaluated for postharvest longevity to further evaluate genes conditioning postharvest longevity. F3 progeny evaluated were derived by selfing F2 selections of long keeping, mid-range, and short keeping types. F2 × F2 progeny evaluated were derived from crosses within and between postharvest longevity categories. Populations for evaluation were grown in the greenhouse in winter 1998-1999 in a randomized complete-block design according to standard forcing procedures. Thirty plants of each genotype were held in the laboratory in deionized water under continuous fluorescent lighting at 22 °C for postharvest assessment. The end of postharvest life was defined as 50% of the flowers drying, browning, or wilting. Data will be presented on postharvest longevity and allelic relationships within populations.

Chemical Ecology of Cottonwood Leaf Beetle Adult Feeding Preferences on Populus

The effect of select Populus clones on adult cottonwood leaf beetle feeding preferences was examined. Field-planted University of Washington poplar pedigree materials—parent clones ILL-129 (Populus delloides) and 93-968 (Populus trichocarpa), F1 clones 53-242 and 53-246, and 87 F2 selections—were used. Both field cage feeding tests with parent and F1 clones, and leaf disc feeding tests with all 91 clones were performed. Feeding stimulants on the leaf surface, long-chain fatty alcohols and α-tocopherylquinone (α-TQ), and phenolic glycosides, tremulacin and salicortin, were analyzed to correlate chemical abundance with cottonwood leaf beetle Chrysomela scripta adult feeding preference. The beetles showed varied feeding preferences among parent clones, F1 clones, and F2 clones. Contents of alcohols, tremulacin, and salicortin did not explain adult beetle feeding preference. Content of α-TQ on the leaf surface did explain the adult beetle feeding preference. The beetles preferred to feed on clones with α-TQ rather than clones without α-TQ. As the amount of α-TQ increased, the feeding preference increased, and then decreased as the amount of α-TQ increased further.

Anther culture of indica/Basmati rice heterotic F1 and F2 hybrids and selection of desirable double haploid lines

Anther culture of indica/Basmati rice heterotic F1 and F2 hybrids and selection of desirable double haploid lines

Florida Red Ruffles and Florida Irish Lace: Two New Lance-leaf Caladium Cultivars

Two lance-leaf caladium cultivars are to be released from the ornamental breeding program at the University of Florida. `Red Ruffles', whose pedigree is Red Frill × (`Red Frill' × `Candidum Jr.'), has elongated medium red leaves with ruffled green margins. Plants are upright with strong petioles, have leaf blades 25 cm long and 14 cm wide, and attain a height of 61 cm when grown in full sun in the field. Plants have more leaves and are more cold tolerant than `Red Frill', the major red lance-leaf cultivar of commerce. Tuber yields of `Red Ruffles' are similar to `Red Frill' but less than `Rosalie', with production indices of 95.0, 97.8, and 121.0, respectively. Foliage of `Red Ruffles' is more upright and less likely to elongate under reduced light than the other cultivars. `Irish Lace', an F2 selection from a cross of “Candidum Jr.' × “Red Frill', has elongated dark green leaves with heavily ruffled margins, which are etched with a thin red border. Leaf blades are 26 cm long and 8 cm wide and have heavy substance. Plant height is 65 cm in the field. Tuber yields of `Irish Lace' are greater than `White Wing', a major green/white cultivar. Use of a green caladium would be as a border or a mixture with red or white lance-leaf cultivars.

Epistasis in an Elite Maize Hybrid and Choice of Generation for Inbred Line Development

Second cycle breeding, utilizing backcross and F2 generations, has become the predominant type of line development program in the U.S. maize (Zea mays L.) industry. Epistasis and linkage have been identified as possible limits to progress from selection in F2 and backcross populations. Objectives of this study were to determine the importance of epistasis in an elite maize hybrid and to determine the appropriate generation for initiation of inbred line development. Six generations of progeny were developed from B73 and B84: the two parental generations, Pl (B73) and P2 (B84); the F2 generation [(B73 × B84) F2]; the BCP1 generation [(B73 × B84) × B73]; the BCP2 generation [(B73 × B84) × B84]; and the F2‐Syn 8 generation (the F2 generation random mated for eight generations). Testcross progeny were produced by crossing random S9 plants from each of the six generations onto the inbred tester Mo17. One‐hundred progeny of F2 × Mo17 and F2‐Syn 8 × Mo17 and 50 progeny of BCP1 × Mo17 and BCP2 × Mo17, as well as the parental testcrosses, were harvested. The experiment was evaluated at four locations in 1990 and three locations in 1991. Epistatic effects were significant for grain yield and grain moisture, and accounted for 21 and 18% of the variation among generation means, respectively. The genetic variance and heritability for grain yield ranked F2‐Syn 8 > F2 > BCP1 > BCP2, but differences among generations were not significant. The predicted gains for each generation ranked in agreement with the heritability. Under low selection intensities (a = 20%), the predicted mean (usefulness) ranked the generations BCP22 > F2 >> F2‐Syn 8 > BCPI. Under high selection intensity (a = 1%), usefulness ranked the generations F2 > F2‐Syn 8 > BCP2 > BCP1. The choice between F2 and backcrosses as source populations is primarily a function of selection intensity. Our results suggest little to no advantage of random mating the F2 before initiating selection and inbreeding.

Inheritance of Aroma in Two Rice Crosses

Two nonscented varieties, ADT38 and ADT39, were crossed with a scented variety, Badshabhog, to study the inheritance of aroma in rice. The parents, F1 and F2 were grown in Nov 1992. For each cross, 2 g of leaf blades from randomly selected parent and F1 plants and 200 F2 plants were soaked in 10 ml of 1.7 percent KOH solution in test tubes and evaluated for scent after 10 min by smelling the contents. All F1 plants were nonaromatic, indicating the recessive nature of the gene controlling aroma. A 15 non-aromatic: 1 aromatic segregation occurred for F2 plants in both crosses, suggesting that two recessive genes control aroma in Badshabhog. Pedigree breeding with a larger population for F2 selection is suggested for introducing scent into nonscented varieties

Selection For Flag Leaf Stomatal Frequency In Bread Wheat

AbstractTwo Cultivars Of Bread Wheat (Triticum Aestivum L.) Showing Significant Differences In Stomatal Frequency On The Adaxial Surface Of The Flag Leaf Blade, Were Hybridized. Transgressive Segregation For Stomatal Frequency Was Observed In The F2 Generation and Selections Were Made For High and Low Stomatal Frequency. In The F9 Generation Two Selections Had Significantly Higher Frequencies Than The Higher Parent. Heritability For Stomatal Frequency Based On Parent‐Progeny Regression Were 42 % (F3—F4) and 81 % (F4—F5). Stomatal Frequency Was Negatively Correlated With The Flag Leaf Blade Area, Mesophyll Cell Size and Grain Size, However, Exceptions Were Observed.

Epistasis of rj1 Nonnodulation of Soybean to Nodulation by Sinorhizobium fredii

Utilization of highly efficient N‐fixing, improved strains of Bradyrhizobium japonicum in soybean [Glycine max (L.) Merr.] inoculants has been hampered because these strains cannot compete in the rhizospbere with indigenous strains. Development of host genotypes that selectively nodulate with introduced strains could improve the field response of soybean to inoculation. Our objective was to determine whether Sinorhizobium fredii USDA 205 could overcome the nodulation block in soybean plants homozygous for the rj1 gene. The rj1 gene produces a nonnondulating phenotype with most strains of B.japonicum. ‘Peking’ is homozygous for the recessive allele conferring the ability to nodulate with S. fredii. Peking was crossed with an isoline of ‘Harosoy’ bearing rj1. We identified F2 plants homozygous for the recessive allele for S. fredii nodulation by selecting for the ability to form nodules with S. fredii. F3 progeny of these F2 selections segregated for the ability to nodulate with B. japonicum 110, indicating segregation for rj1. The results indicate that the two traits are controlled by different loci that are not tightly linked. In a separate test, F2 plants homozygous for rj1 were selected and allowed to self. Ten seeds from each of four F2 rj1 plants were inoculated with S. fredii, but none formed nodules, showing that rj1 nonnodulation is epistatic to nodulatlon by S. fredii. We surmise that rj1 cannot be used in conjunction with an S. fredii inoculum to overcome the problem of bacterial competition for nodule occupancy.

Modified Early Generation Testing Procedure for Yield Selection in Soybean

An early generation testing program to identify crosses with superior yield potential and F2 plants within these crosses which receive a superior complement of yield genes would be useful in soybean [Glycine max (L.) Merr.] breeding. Early generation testing is effective in identifying superior yielding pure lines, but requires extra yield testing. This paper describes a modified early generation testing procedure where the number of yield test plots required per cross has been reduced from 1860 to 175 plots, allowing a 10‐fold increase in the number of crosses that are evaluated per year. This was accomplished by reducing the number of F2‐derived lines per cross from 300 to 30 and by using single location, single replication data as a basis for selection in F2.3 through F2.4.6. This modified early generation testing procedure has been used in a soybean breeding program since 1972, resulting in the release of eight high‐yielding soybean cultivars.

F3 response to F2 selection for quality and its effect on F3 yield distribution

Seed of F2 single plant selections from two crosses was evaluated using a number of small-scale quality tests.F2 quality test values were significantly correlated with farinograph and extensograph properties in the F3, but no one test was correlated with all of the physical dough measures. The Pelshenke time and the proportion of residue protein were the small-scale measures most consistently correlated with dough strength (farinograph dough breakdown and extensograph maximum resistance) in the F3 and between the F2 and F3 generations.Applications of independent culling in the F2 for each test did not alter the subsequent nature of the F3 yield distribution except for flour protein content and Zeleny volume, where there was a preferential loss of lines from the higher yielding end. This resulted from the negative correlations between flour protein content and yield, both within the F3 (r=-0.66**) and between the F2 and F3 (r= -0-44**). The negative relationship between grain yield and Zeleny volume was due to the effect of protein content on Zeleny volume.Application of quality testing regimes that estimated grain hardness, protein content and dough strength in the F2 did not adversely affect the nature of the F3 yield distribution, yet permitted up to 71% of the population to be removed because of unsatisfactory balance of quality attributes. These results have considerable implications for the planning of wheat breeding programmes.Additional keywords: Bread wheat (Triticum aestivum L.), sodium dodecyl sulfate sedimentation volume, Zeleny sedimentation volume, Pelshenke wheatmeal fermentation time, residue protein content.