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Broccoli phytochemical content

By location and season

For the glucosinolates, glucoraphanin and glucobrassicin repeatability at

each location, season and treatment trial were comparable and generally

high (0.83-0.97) between organic and conventional trials, while no clear

trend for neoglucobrassicin repeatabilities was observed between organic

and conventional aside from being much lower than glucoraphanin and

glucobrassicin (Supplemental Table 5.3). For γ- and α-tocopherol, repeatabilities

were comparable between organic and conventional, while for δ-tocopherol

repeatabilities were comparable between systems or higher in conventional

except for one paired trial. For the carotenoids, repeatabilities were comparable

or higher in organic for all paired trials, while for lutein in seven of the eight paired

trials organic was comparable or greater than conventional. Repeatabilities for

zeaxanthin concentrations were comparable for six of the eight paired trials.

Table 5.4 Repeatabilities, genetic correlation and ratio of correlated response to direct response for

broccoli phytochemicals comparing organic versus conventional management systems over all trial
season/location combinations, 2006-2008.

Repeatability (H)

ra CR /R b A org org
CO

Glucoraphanin 0.84 0.82 0.84 0.83
Glucobrassicin 0.70 0.64 0.88 0.84

Neoglucobrassicin 0.75 0.76 0.94 0.94

δ-Tocopherol 0.50 0.42 0.73 0.66

γ-Tocopherol 0.75 0.72 0.95 0.93

α-Tocopherol 0.23 0.35 0.61 0.76

Lutein
0.83 0.85 0.93 0.94

Zeaxanthin 0.76 0.77 0.77 0.78

β-Carotene
0.62 0.72
0.63 0.68

a Average genetic correlation between conventional and organic production systems across locations.

b Ratio of correlated response to direct response.

5.3.4 Comparison of cultivar ranking for phytochemical concentration

and stability across trials

To determine trends in cultivars with both the highest concentration of

phytochemical groups most stable across locations, seasons and production

systems, phytochemical concentrations were plotted against stability per

genotype across trials. A group of cultivars were identiied as both highest

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