Page 164 - Breeding and regulatory opportunities, Renaud

Chapter 5

Previous studies comparing organically versus conventionally grown broccoli for

nutritional quality have been‘market basket’(of-the-shelf ) studies (Wunderlich

et al., 2008; Koh et al., 2009). Harker (2004) explained that the limitation of

market basket studies is that they either have purchased the products from

the store shelf and cannot relate diferences to speciic growing conditions or

that the number of cultivars is too small to generalize the results. While other

studies have compared cultivars from one production season time period to

another, knowledge of the actual cultivar and production system (soil quality,

temperature, rainfall) was not available (Benbrook, 2012; Davis et al., 2004). The

concentrations and form of health-promoting nutrients in Brassica vegetables

have been reported to vary signiicantly due to (1) genotype (cultivar and

genotypic class) (Carlson et al., 1987; Kushad et al., 1999; Schonhof et al., 2004;

Farnham et al., 2005; 2009; Ibrahim and Juvik, 2009; Wang et al., 2012; Traka

et al., 2013), (2) environmental conditions such as season (Rosa et al., 2001;

Vallejo et al., 2003ab; Charron et al., 2005ab; Aires et al., 2011), light (Brown

et al., 2002), max/min temperature, irrigation (Pek et al., 2012; Schonhof et al.,

2007), (3) genotype by environment interactions (Brown et al., 2002; Farnham et

al., 2004; Björkman et al., 2011); (4) management system including soil fertility

(Robbins et al., 2005; Xu et al., 2010 ), organic versus conventional (Meyer and

Adams, 2008; Naguib et al., 2012; Picchi et al., 2012), days to harvest (Vallejo et

al., 2003ab), and (5) post-harvest management (Hansen et al., 1995; Tiwari and

Cummins, 2013). Identifying speciic growing conditions and genotypes that

produce cultivars with varying phytochemical content and putative disease-

prevention activity could ofer value-added commercial opportunities to the

seed and food industry.

In addition to research conducted on how broccoli genotypes, management

system and environment interact for horticultural traits (Renaud et al., 2014), we

address in this chapter the question of how do genotypes, management system

and environment interact to determine the nutritional contributions of broccoli

to the human diet. We studied the relative importance and interaction among

genotypes (cultivars, genotypic classes) and environment {management system

[M: organic (O) or conventional (C)], season (S, a combination of year and season

within year, i.e., fall 2006, spring 2007, fall 2007, spring 2008), location (E)} in a

set of 23 broccoli cultivars for loret glucosinolate, tocopherol and carotenoid

concentrations grown under organic and conventional production systems

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