Page 152 - Breeding and regulatory opportunities, Renaud

Chapter 4

Northern Italy compared to cultivars that were bred outside of the intended

region. Annicchiarico et al. (2010) also found that when comparing G × M to

G × L, the efect of wheat selected for a speciic bioregion outweighed the efect

of breeding for management system for direct selection of yield. Speciic to

broccoli, Crisp and Gray (1984) reported that to develop cultivars for a speciic

season, populations from diferent maturity groups should be used to take

advantage of high heritability in heading characteristics, head color and time

of maturity.

The stability between the organic and conventional trials across most trials,

and comparable heritability between systems for most traits, would suggest

that selection for broccoli for organic systems would best be carried out under

organic conditions. Lorenzano and Bernardo (2008) suggest that breeding for

adaptation to organic production environments could be conducted under

conventional conditions due to high correlations, with the caveat that advanced

breeding lines be tested under organic conditions for less heritable traits such

as yield. However, in our trials, there was signiicant crossover interaction at

the individual trial level as well as low rank correlation when genotypic classes

were separated in the ranking analysis. Considering these indings (and without

taking costs into account), a separate organic regional, seasonal breeding

program for broccoli can be efective. This is further supported by the fact

that the ratio of correlated response to direct response in our trials for most

traits was close to but below 1.0 implying that selection directly in an organic

environment could result in more rapid genetic gain than indirect selection in

a conventional environment.

The large genotype variance observed in our organic trials relative to

conventional trials indicated that the potential for breeding within an organic

system may beneit cultivar development for both management systems.

Because organic management systems do not use synthetic fertilizers and

pesticides, the potential for a breeder to observe and select parent lines for

nitrogen use eiciency, disease resistance and vigour, under organic systems

may bring beneits to the breeding program. Due to the diferent management

practices, locations and seasonal diferences in organic farming across the

US, such screening could provide additional information about breeding line

performance, and support in determining which lines are most stable across

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