Inter-plot competition in yield trials of swedes (Brassica napus ssp. rapifera L.)

Bradshaw, J. E.

doi:10.1007/bf00042624

Cited by 17 publications

(17 citation statements)

References 6 publications

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“…(1986) showed that interplot competition of differentheight triticale and wheat genotypes caused significant bias and cautioned that ordinary randomization or increased replication would not eliminate the bias . Results more relevant to early generation selection were reported by Bradshaw (1989) spacing are unsatisfactory for yield assessment . Kramer et al .…”

Section: Discussionmentioning

confidence: 99%

Correlations between auto-, allo- and nil-competition and their implications in plant breeding

Fasoula

1990

Euphytica

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This study was undertaken to explore the relation between auto-, allo-and nil-competition using a long established pure line cultivar of bread wheat, where genes controlling yielding and competing ability co-exist and co-interact . The investigation lasted three growing periods, the first two with trials grown at nilcompetition (100 cm), and the third with trials grown at the three conditions of competition . In the first growing period, divergent single plant honeycomb selection for high and low yield was applied in the cultivar Siete Cerros, to continue in the second growing period with divergent line honeycomb selection . In the third growing period, top and bottom lines selected under nil-competition were compared with the mother variety Siete Cerros under auto-, allo-and nil-competition .Correlation coefficient estimates between auto-, allo-and nil-competition demonstrated that auto-competition and nil-competition are correlated positively interse and negatively with allo-competition . In general, the results suggest that yielding and competing ability are correlated negatively .The implications of the findings are discussed in relation to the possibility of (1) selecting for heritable high yield on a single plant basis, (2) avoiding biased results due to interplot competition, (3) substituting cultivar degeneration for cultivar improvement .

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Section: Discussionmentioning

confidence: 99%

Correlations between auto-, allo- and nil-competition and their implications in plant breeding

Fasoula

1990

Euphytica

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“…Their assessment in single-row plots would not require unrealistically high levels of resources if there were few replicates. Interplot competition is unlikely to be a serious problem in an outbreeding root crop such as turnip, where the aim is an open-pollinated cultivar, in contrast to kale, where competition arises from height differences and very tall cultivars are undesirable (Bradshaw 1986), and swede, which is a root crop where inbred cultivars are grown in pure stands (Bradshaw 1989). The formula for the response to selection given earlier was used to determine the optimum balance between the intensity of selection and heritability as affected by the number of trials and replicates within trials for a fixed total number of plots.…”

Section: Discussionmentioning

confidence: 99%

Turnip (Brassica rapa L. ssp. rapifera Metzg.) population improvement and cultivar production

Bradshaw¹,

Gemmell²,

Gowers³

et al. 2002

Plant Breeding

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In 1977, a fodder turnip breeding programme was started from seven cultivars with the primary aim of increasing dry-matter yield. The breeding method chosen was population improvement by half-sib family selection on a biennial cycle. Seed production in polythene tunnels with blowflies as pollinators was followed by assessing the resulting progenies in replicated yield trials and observation plots from which plants were selected for the next cycle. Six generations of selection resulted in a population with a yield that was 25% higher than the mean of the initial seven cultivars. This was remarkably close to the predicted superiority of the population, despite a significant discrepancy in one generation. It is concluded that the greatest response to selection per year would be achieved by selecting eight families from 128 assessed for 1 year in trials at two or three sites with an overall total of six replicates, given a resource limit of 800 plots.

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“…There was, after all, reasonable agreement between the predictions from the TTC and those based on the F3 generation, despite the latter containing a small dominance component. The effects of interplot competition in early generation trials could be reduced by statistical modelling (Bradshaw, 1989), and more than one sowing date in the F5 generation might provide useful genotype x environment interaction information before deciding which lines to multiply as potential cultivars. Finally, it should be possible to use the genetical information from the two crosses in computer simulations of various inbreeding and selection schemes in order to choose the best scheme to use in practice.…”

Section: Discussionmentioning

confidence: 99%

The inheritance of quantitative traits in Brassica napus ssp. rapifera(swedes): augmented triple test cross analysis of yield

Ramsay

Bradshaw²,

Kearsey

1994

Heredity

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Two augmented triple test crosses were produced from inbred lines of swede (Brassica napus ssp. rapifera L.) and assessed in field trials at Dundee in 1988 and 1989, respectively. The first cross was between lines derived from cvs. Criffel and Marian and the second between the same Criffel line and one from Bangholm Wilby. The genetic architectures of the two components of dry weight yield were clearly different. Dry-matter percentage was mainly under the control of additive genetical variation whereas fresh weight yield was under the control of additive and dominance variation. Although there was unidirectional dominance (positive [h]) for high yield, the dominance ratio was less than unity in both crosses. Dry weight yield was also under the control of genes showing both additive and dominance variation. In both crosses fh] was larger than [d} and the F1 outyielded the better parent by 14 and 12 per cent, respectively. The dominance ratio was less than unity, being 0.50 and 0.94 respectively. There was no evidence of overdominance. Whilst epistasis was not a major feature of the genetic architecture of dry matter yield and its components, there were large and unexpected reciprocal differences, particularly for fresh and dry weight yield in all TTC generations and the F3 of the first cross. These require further investigation. Finally it was concluded that it should be possible to produce inbred cultivars of swede which outyield F1 hybrids in a modest sized breeding programme because 12 and 2 per cent, respectively, of the recombinant inbred lines from the two crosses were predicted to outyield the F1.

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Inter-plot competition in yield trials of swedes (Brassica napus ssp. rapifera L.)

Cited by 17 publications

References 6 publications

Correlations between auto-, allo- and nil-competition and their implications in plant breeding

Correlations between auto-, allo- and nil-competition and their implications in plant breeding

Turnip (Brassica rapa L. ssp. rapifera Metzg.) population improvement and cultivar production

The inheritance of quantitative traits in Brassica napus ssp. rapifera(swedes): augmented triple test cross analysis of yield

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