Page 126 - Breeding and regulatory opportunities, Renaud

Chapter 4

system and regionally appropriate fertility application tools, and the applied

supplemental irrigation for the area of study. Cropping history and rotation are

outlined per location. Mechanical and hand weed management were practiced

for all sites. Baseline soil sampling for basic soil characteristics was performed

as subsampling within plots, per trial site location prior to the start of each

seasonal trial at the time of trial planting. Soils were analysed for pH, labile

(available) N (ppm) and Particulate Organic Matter (POM), a measure of longer

term available nitrogen taken pre-fertilization (N/kg soil). There were no pest

control applications in organic ields. In the conventional trials diazinon was

used for control of radish maggot and carbaryl (Sevin) was used for lea beetle

control.

4.2.5 Weather

Weather data was collected from the two regional meteorological stations

relative to the ield experiments in Maine and Oregon to include maximum

/minimum temperatures and precipitation per day for each trial duration.

Growing degree days (GDD) were calculated per trial by taking the average of

the daily maximum and minimum temperatures minus the base temperature

for broccoli (4.4oC) across each trial period (Maynard and Hochmuth, 2007).

4.2.6 Field Data Collection

As plots approached maturity they were evaluated three times a week for

broccoli heads that had reached commercial market maturity (approximately

10 to 12 cm in diameter for most of the cultivars while retaining irmness as

an indicator of maturity) and were evaluated for quality traits. Field quality

evaluations were measured on a 1 to 9 ordinal scale. Traits included head shape

(1 = lat shape; 9 = high dome shape), head surface (1 = very uneven; 9 = smooth

head), head color (1 = pale green; 9 = dark green), bead size (1 = large beads;

9 = small beads), bead uniformity (1 = not uniform; 9 = excellent uniformity),

plant height (mean measurement of height of plant from base of stalk to tips of

leaves in cm) and an overall plot quality rating (1 = poor overall performance;

9 = excellent overall performance) based on overall appearance, head quality

and uniformity of the entire plot. Five broccoli heads were trimmed to a uniform

length of 18 cm from the crown to stalk at maturity. For each of the ive heads,

head weight (g) and head diameter (cm) was measured. To determine average

head weight (HW) the mean was taken of the sum of the ive individual head

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