Page 220 - Breeding and regulatory opportunities, Renaud

Chapter 6

and the tocopherols were more inluenced by environment and various

interactions. We identiied distinct positive and negative trait correlations (e.g.

glucoraphanin positively correlated with head weight and negatively correlated

with carotenoids). For the content of the glucosinolates, glucobrassicin and

neoglucobrassicin, the early maturing Fhybrids and open pollinated varieties
1
had the highest levels, while for glucoraphanin highest levels were found in the

late maturing Fhybrids. For traits that were strongly associated with genotype
1
main efect (i.e. glucoraphanin and lutein) the cultivars with the highest

concentrations of these compounds were also the most stable across trials.

Season efect was greater compared to the location (Maine versus Oregon) efect

for the phytochemicals compared to the horticulture traits (glucoraphanin being

higher in fall environments; carotenoids higher in spring environments). Unlike

the horticultural traits, phytochemical variances were not larger in organic

compared to conventional growing conditions, but repeatabilities and the ratio

of correlated response to direct response were similar, which would support the

beneit of selecting in organic systems to optimize nutrition targeted breeding

programmes.

We can summarise our indings as follows. The three hypotheses stated at the

start of the research reported in this thesis were: (1) An organic seed regulation

is a necessary step toward an optimized organic seed sector, (2) Cultivars bred

for high input conventional growing conditions may not be optimal for organic

farming systems, and (3) Organic production systems produce crops of higher

nutritional value. Hypothesis 1 and 2 were conirmed by our study. Hypothesis

3 was not conirmed. We found that genotypic, location and season main efects

were more important and that no major diferences were found for nutritional

value by management system. These indings are elaborated in section 6.3.

202