Page 27 - Breeding and regulatory opportunities, Renaud

General introduction

1.3.3 Organic cultivar requirements for improved nutritional value

The genetic potential of organically-grown cultivars for high nutrient quality had

been a concern for many years of the organic industry. Organic growers shared

a general concern that modern elite cultivars (mostly Fhybrids) might lack
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the nutritional quality of older open pollinated cultivars (Murphy et al., 2008).

Indirect evidence supporting this argument had been published by Davis et al.

(2004), who compared USDA nutrient content data for 43 garden crops, from

their statistical records from 1950 to 1999. Statistically signiicant declines were

noted for 6 nutrients (protein, calcium, potassium, iron, ribolavin, and ascorbic

acid), with declines ranging from 6% for protein to 38% for ribolavin. Davis

et al. (2004) attributed the decreases in nutrient content in part to changes in

the cultivars used. Cultivars in 1950 had been bred to be adapted to speciic

regions and a relatively low input agriculture system, while the more modern

varieties had been selected for yield, disease resistance, broad adaptation in

high input agriculture systems, and for increased‘shipability’and shelf life. It was

hypothesised that selection of cultivars for traits such as growth rate, yield, pest

resistance, or other non-nutrient characteristics, might be subject to metabolic

trade-ofs that result in limitations in the cultivars’ abilities to incorporate soil

minerals, transport them within the plant, or synthesize nutrients such as

proteins, vitamins, and other phytochemicals (Morris and Sands, 2006).

The literature showed that concentrations of health-promoting nutrients in

Brassicas depend on the cultivar, season and management system in which

they were grown, including organic versus conventional conditions (Farnham

et al., 2004; Charron et al., 2005a, 2005b; Meyer and Adams, 2008). It was widely

accepted that genotype played an important role in determining the level of

nutrients in a crop cultivar (Munger, 1979; Welch and Graham, 2004). What was

unclear, however, was to what extent there is a genotypic efect and trade-ofs

between diferent nutritional compounds and whether the nutritional content

of a cultivar was associated with certain genotypic classes, e.g. open pollinated

versus Fhybrid. There was also no clear diferentiation as to whether nutritional
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content in a crop was driven by genotypic class or whether it varies due to

genotype by environment interaction. It was hypothesized that identiication

of growing conditions and genotypes that can provide products with various

phytochemical content and putative disease-prevention activity could ofer

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