Page 232 - Breeding and regulatory opportunities, Renaud

Chapter 6

cross-examined trait performance and sought explanations for cultivar trait

performance diferences. The more recently released cultivars were higher

yielding, earlier maturing, more uniform, had shorter plant/head placement

architecture and had darker, and higher domed heads compared to ‘Arcadia’.

These cultivars appeared to be more responsive to nitrogen availability, and

produced larger heads and taller plants in organic compared to conventional

trials, but developed very quickly and were prone to hollow stem. ‘Arcadia’

comparatively had a very high head placement in the plant facilitating ease of

harvest and a latter head shape (not preferred) and no incidences of hollow stem.

For the trait overall quality, ‘Arcadia' was a top performer in the Fall trials, but not

in Spring trials. Overall quality appears to represent a group of characteristics

including plant/head uniformity, vigor, and head quality as determined from

our genetic correlations. ‘Green Magic’ had strong overall quality ratings in

both seasons indicating the cultivar’s adaptation to cold conditions and early

vigor under lower nitrogen conditions. In this study, there were ive cultivars

in the quadrant of greatest stability and highest head weight per production

system (Chapter 4). Between production systems in the ranking by growers,

of the ive top performing hybrids, three overlapped and two were diferent.

The example of ‘Arcadia’ brings to light the importance of yield stability over

yield per se for the growers that attended our ield day. ‘Arcadia’ demonstrated

a capacity to produce suiciently high yielding heads across years of adequate

head quality for their markets. It also brings to light the importance of the stage

in which non-target location growers are exposed to new cultivars along the

commercialization chain. The growers at our ield day had never heard of ‘Green

Magic’, yet it had been on the market for several years already.

Genotype class and breeding techniques

In the context of this study, the analysis aimed at identifying commercial

broccoli cultivars that might be suitable for organic agriculture, and in so doing,

identify traits for crop improvement that would be translated into a breeding

program to optimize broccoli for organic agriculture. Some organic farmers

in our study indicated that they preferred cultivars that were open pollinated

(OP) and provided harvestable side shoots after the primary inlorescence was

harvested to service their market type. The majority of cultivars in our trials

were single-harvest heading hybrids. Of the top cultivars identiied for head

weight, across locations, seasons and management system ‘Green Magic’ as

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