Page 234 - Breeding and regulatory opportunities, Renaud

Chapter 6

license for the cultivar. Diversity in a breeding program could be enhanced

if sources of variation in the genus Brassica were exploited to enhance levels

of health-promoting phytochemicals and to broaden the genetic diversity of

commercial broccoli germplasm. A molecular marker survey of Brassica species

could be useful to determine where high levels of genetic variation may exist that

could be used to broaden the genetic base of existing Brassica crops. Enhancing

both the genetic diversity of parental lines in conjunction with breeding for

performance in various environments is needed by the broccoli industry.

The value of genetic diversity in a breeding program could be taken a step

further by considering breeding not for one cultivar at a time, but by considering

the cultivar needs for an entire growing season in order to develop a broccoli

assortment for each slot in a production cycle per region (a spring, summer,

fall ‘seasonally slotted broccoli program’). Crisp and Gray (1984) reported that

to develop broccoli cultivars for a speciic season, populations from diferent

maturity groups should be used to take advantage of high heritability in heading

characteristics, head colour and time of maturity. Direct selection in organically

managed ield conditions for genotypes targeted for organic agriculture ofers

advantages over indirect selection in conventionally managed ield conditions

because breeding populations selected in organic environments have

higher yields when grown organically, compared to conventionally selected

populations that did not perform comparatively well (Kirk et al., 2011). In further

studies, early generation broccoli breeding lines and/or populations should be

compared to attain a better prediction of genetic correlations for organic, and

to explore potential changes that may occur when broccoli breeding lines are

bred in the target environment (location and season) from the initiation of the

program.

Efective utilization of genetic correlations in breeding for health promotion

When considering breeding targeted for consumers concerned with the health

consequences of what they eat, genetic correlations integrating horticultural

and phytochemical traits for crop improvement need to be considered. We

found some positive correlations and some trade-ofs that would apply to

setting priorities in strategizing for breeding initiatives that target health

promotion against cancer (glucoraphanin) and degenerative eye diseases (the

carotenoids). Speciically, the genetic correlations from this study demonstrated

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