Page 135 - Breeding and regulatory opportunities, Renaud

Broccoli crop improvement

(261 g) the genotypic efect for most traits was larger in Oregon compared to

Maine. As with the overall analysis, the M main efect was zero or small. Among

M interactions the largest source of variation was associated with G×Y×S×M

in both Maine and Oregon, with variances generally larger in Oregon (data

not shown). When trials were analysed by S and L separately, M main efect

was also not signiicant for head weight and most traits; only in Maine Fall did

the M have a large efect on plant height (data not shown). When trials were

analysed at the paired trial level per L, S, and Y level, we found that the G × M

interaction was often signiicant (53 of 72 interactions (74%) for nine traits x

eight environments). For head weight, seven of eight trials showed signiicant

G × M interaction, while all additional traits also showed signiicance in G × M

interaction in ive to seven of the eight trial combinations (data not shown).

4.3.2 Comparison of head weight and other horticulture traits over the

environments

Location, Season, Management System Overall

Results across all S, L, and M system trials for Oregon showed a signiicantly

higher overall head weight compared to Maine trials, (Figure 4.1a). Mean head

weight of broccoli cultivars in the Fall trials was signiicantly higher than in the

Spring trials for all L, S and M combinations (Fall 397 g; Spring 214 g), (Figure

4.1b). In the Fall, the magnitude of the diference in head weight between

Oregon (474 g) and Maine (321 g) were much larger than the diference in

Spring (Oregon 225 g versus Maine 202 g). Organically produced broccoli (head

weight overall 315 g) performed as well as conventionally produced broccoli

(296 g) (Figure 4.1c). Head weight across all organic trials had a wider range and

greater variance among cultivars compared to conventional trials. An overview

of location and season mean head weight are presented in Figure 4.1d.

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