Page 182 - Breeding and regulatory opportunities, Renaud

Chapter 5

the experiment was conducted in only one location over two growing seasons.

For the other compounds such as α-tocopherol and β-carotene, L×S and the

G×L×S interactions were most important.

Overall we found high genetic correlations between glucosinolates in organic

and conventional trials. When trial locations were analysed separately, M

main efect was present for glucobrassicin and neoglucobrassicin. The

mean concentrations of glucobrassicin and neoglucobrassicin in broccoli

from Oregon organic trials had higher concentrations compared to Oregon

conventional trials, while Maine trials were comparable between management

systems (Table 5.2, Supplemental Figure 5.1A-C). These results can be

explained by the larger environment efect on glucobrassicin and genotype

by environment efect on neoglucobrassicin found in the variance component

analysis indicating sensitivity of these compounds to abiotic and/or biotic

stresses. Our location speciic indings are supported by those of Meyer and

Adam (2008) who performed a comparative study of the glucosinolate content

of store bought organic and conventional broccoli and determined that the

indolyl glucosinolates, glucobrassicin and neoglucobrassicin were signiicantly

higher in the organically grown versus the conventionally grown. Evaluation of

10 broccoli genotypes over two years by Brown et al. (2002) further supports

our indings and those of Rosa and Rodrigues (2001), Vallejo et al. (2003), and

Farnham et al. (2004), that variation in concentration for glucoraphanin was

primarily due to genetic variation, while diferences in glucobrassicin was

due to environmental variation (e.g. season, temperature) and genotype by

environment interaction. The signiicantly higher levels of glucobrassicin in

Oregon in the Fall harvested trials compared to Maine could be attributed to

the higher maximum temperatures and GDD in Oregon compared to Maine.

Compared to glucosinolates, there is substantially less research on the genotype

by environment interaction of tocopherol and carotenoid phytochemical

groups in broccoli, and no speciic studies exploring the inluence of organic

production system. In our study, minor management system efect at the overall

trial analysis level was observed for the tocopherols and for carotenoids, there

was management system efect only for lutein in Oregon Spring trials. Picchi

et al. (2012) also did not ind diferences in levels of carotenoids in caulilower

in organic versus conventional systems. In the tocopherols, there were no

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