Page 143 - Breeding and regulatory opportunities, Renaud

Broccoli crop improvement

4.3.5 Stability of genotype performance

The results of the stability analysis of a cultivars capacity to perform comparably

across trial locations, and seasons in the diferent management systems

for head weight indicated that under both management systems, ‘Belstar’,

‘Batavia’, and‘Green Magic’were similar across environments (Figure 4.2a and b).

‘Arcadia’was highly stable across organic trials (ranked 5th), but less stable across

conventional trials (ranked 11th). Because we were interested in the broccoli

cultivars that provide both an acceptable yield and displayed stability across

environments, we combined the analysis of head weight ranking with stability

across environments, using 300g as a minimum threshold for weight and 15 g2

as a maximum threshold for stability (Figure 4.2a and b). In that quadrant

the cultivars ‘Batavia’, ‘Belstar’ and ‘Green Magic’ had the highest combined

stability and head weight across both management systems. In the top group

of most productive and stable cultivars also ‘B1 10’ appeared in conventional

trials (Figure 4.2a), and ‘Arcadia’ and ‘Everest’ in the organic trials (Figure 4.2b).

The open pollinated and inbred cultivars ‘OSU OP’, ‘Nutribud’, ‘Early Green’ (OPs)

and USVL 048 and 093 (inbreds) had the lowest head weight and least stability

across trials. In the combined head weight and stability analysis, the Fhybrid

1
cultivar ‘Diplomat’ was in the bottom performing group overall.

4.3.6 Correlation among horticulture traits

The correlation analysis between genotypic means across trials, separately

for organic and conventional management system, shows that head weight

was positively and highly correlated with head size, bead size, bead uniformity

(conventional only), and overall quality (Table 4.8). Conversely, head weight was

negatively correlated with head color, but it was not signiicant. There was a

signiicant positive correlation for head shape and bead size in both systems.

Overall quality was highly correlated across both management systems for head

weight, head diameter, bead uniformity, head surface, and bead uniformity and

in conventional systems for head shape and bead size.

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