DYNAMIC RELATIONSHIPS BETWEEN FIELD TEMPERATURES AND BROCCOLI HEAD QUALITY

Fifty-six field plantings of 'Baccus', 'Citation', 'Packman', and 'Sou thern Comet' broccoli were made in Charleston, S.C., at 2-week interva ls from February to November from 1990 to 1999. The objective was to d etermine broccoli's response to growing season mean (GSM) temperatures for several important market quality characteristics, such as head sh ape, color, density, leafiness, and bead size. Regression analysis det ermined whether quality was more affected by GSM minimum (min) or maxi mum (max) temperature for each head quality characteristic. Head leafi ness and density of 'Baccus' were insensitive to GSM min (7.0 to 23.5 degrees C) and GSM max (17.5 to 32.5 degrees C) temperatures experienc ed during these years, 'Baccus' head color was unacceptable at <20.3 d egrees C GSM max and head shape was unacceptable at <19.8 and >26.8 de grees C GSM max. 'Citation' head color and leafiness were unacceptable at >20.5 and >20.2 degrees C GSM max, respectively. Head density of ' Citation' was unacceptable at <19.2 and >28.9 degrees C GSM max and he ad shape was unacceptable at <18.4 and >25.7 degrees C GSM max. Qualit y of 'Packman' was unacceptable for head color at <21.0 and <27.3 degr ees C GSM max, head leafiness at >32.0 degrees C GSM max, head density at <8.4 and >18.0 degrees C GSM min, and head shape at >22.0 degrees C GSM max. 'Southern Comet'' head quality was unacceptable for head co lor at <9.2 and >16.5 degrees C GSM min, head leafiness at >32.0 degre es C GSM max, head density at <8.9 and >16.2 degrees C GSM min, and he ad shape at <21.0 and >25.3 degrees C GSM max. GSM min or max temperat ures did not affect bead size of any cultivar during any planting time studied.