Page 123 - Breeding and regulatory opportunities, Renaud

Broccoli crop improvement

resulting in the recommendation that cultivars intended for organic agriculture

should be selected only under organic conditions. Secondly, other studies

indicated that rankings in cultivar performance between management systems

were similar with high genetic correlations, suggesting that breeding can be

conducted under conventional conditions, with the caveat that advanced

breeding lines can be tested under organic conditions for less heritable traits

(e.g. Löschenberger et al., 2008; Lorenzano and Bernardo, 2008).

The vegetable seed industry has not developed broccoli cultivars selected

for performance in organic management systems. As a result, a collective of

public breeders and organic growers have attempted to develop bioregionally

bred broccoli cultivars for organic systems (see Northern Organic Vegetable

Improvement Collaborative; www. http://eorganic.info/NOVIC). In the interim,

this leaves no choice but for organic growers to use cultivars bred under

conventional conditions for many crops (Lammerts van Bueren and Myers,

2012). While seeds of some cultivars are produced under organic conditions,

the majority of organic producers are using conventionally produced and post-

harvest untreated seeds (Dillon and Hubbard, 2011). With the private sector

becoming more interested in breeding for the organic market, many questions

arise as to what are the highest priority traits, what is their heritability under

variable, sometimes low-input organic growing conditions, and what is the

most appropriate selection environment. In order to better understand how

and whether broccoli cultivars perform diferently under organic conditions

and to determine whether selection under organic growing conditions is

necessary to service the needs of growers in diverse regions, a large genotype ×

environment × management (G × E × M) study with 16 ield trials was established

in Oregon and Maine to evaluate a diverse set of cultivars, trialled under organic

and conventional management. The study aimed to address the following

questions: (1) do currently available broccoli cultivars perform diferently for

head weight and other horticulture traits in organic compared to conventional

management systems in diferent regions and diferent seasons; (2) is the relative

ranking of cultivars the same under organic and conventional conditions; (3)

does heritability difer for certain traits under organic conditions compared to

conventional conditions; and (4) under which growing conditions and in what

locations would selection for broccoli cultivars for organic agriculture be most

efective?

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