Page 249 - Breeding and regulatory opportunities, Renaud

Summary

system. The cultivars with the highest concentrations of glucoraphanin had

the lowest for glucobrassicin and neoglucobrassicin. The genotypes with

high concentrations of glucobrassicin and neoglucobrassicin were the same

cultivars and were early maturing Fhybrids. Cultivars highest in tocopherols
1
and carotenoids were open pollinated or early maturing Fhybrids. Distinct
1
locations and seasons where phytochemical performance was higher for each

compound were identiied. Correlations among phytochemicals demonstrated

that glucoraphanin was negatively correlated with the carotenoids and the

carotenoids were correlated with one another. Little or no association between

phytochemical concentration and date of cultivar release was observed,

suggesting that modern breeding has not negatively inluenced the level of

tested compounds. We found no signiicant diferences among cultivars from

diferent seed companies.

In the ield trial component of these studies, the organic trial locations were

intentionally selected to be farms under long term organic management as

less mature organic farms or those in conversion may more closely resemble

conventionally managed farms. Our organic trials produced comparable

head weight to the conventional trial locations, and therefore the level of the

environmental stress that we hypothesized would afect trait performance

and phytochemical content was minimal. For most traits, there was no

management efect across environments. Management main efect was only

identiied at the per trial level, demonstrating that each individual location/

season/year combination constituted a unique environment, and that

genotype by management system interactions resulted from diferent factors

in each environment. Larger genotypic variances in organic environments for

horticultural but not phytochemical traits were observed, demonstrating the

innate heterogeneity in the organic agricultural system and varietal response

to such variation.

As with horticultural traits, management main efect did not play a signiicant

role across trials in the phytochemical component of the trials. At the individual

compound level, genotype main efect was most important for glucoraphanin,

neoglucbrassicin and the carotenoids, while glucobrassicin and the tocopherols

were more inluenced by environment and various interactions. We identiied

distinct positive and negative trait correlations (e.g. glucoraphanin positively

231