Page 160 - Breeding and regulatory opportunities, Renaud

Chapter 5

Variation in broccoli cultivar phytochemical content under organic and

conventional management systems: Implications in breeding for nutrition

Erica N.C. Renaud, Edith T. Lammerts van Bueren, James R. Myers,

Maria João Paulo, Fred A. van Eeuwijk, Ning Zhu, John A. Juvik

(accepted by PLOS ONE, in press)

Abstract

Organic agriculture requires cultivars that can adapt to organic crop

management systems without the use of synthetic pesticides as well as

genotypes with improved nutritional value. The aim of this study encompassing

16 experiments was to compare 23 broccoli cultivars for the content of

phytochemicals associated with health promotion grown under organic and

conventional management in spring and fall plantings in two broccoli growing

regions in the US (Oregon and Maine). The phytochemicals quantiied included:

glucosinolates (glucoraphanin, glucobrassicin, neoglucobrassin), tocopherols

(δ-, γ-, α-tocopherol) and carotenoids (lutein, zeaxanthin, β-carotene). For

glucoraphanin (17.5%) and lutein (13%), genotype was the major source of

total variation; for glucobrassicin, region (36%) and the interaction of location

and season (27.5%); and for neoglucobrassicin, both genotype (36.8%) and its

interactions (34.4%) with season were important. For δ- and γ- tocopherols,

season played the largest role in the total variation followed by location and

genotype; for total carotenoids, genotype (8.41-13.03%) was the largest source

of variation and its interactions with location and season. Overall,

phytochemicals were not signiicantly inluenced by management system. We

observed that 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
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and carotenoids were open pollinated or early maturing Fhybrids. We
1
identiied distinct locations and seasons where phytochemical performance

was higher for each compound. Correlations among horticulture traits and

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

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