Pigment Distribution and Total Dissolved Solids of Selected Cycles of Table Beet from a Recurrent Selection Program for Increased Pigment

Abstract

Half-sib recurrent selection programs were initiated at the University of Wisconsin-Madison in 1978 and 1995 to increase betalain (betacyanin and betaxanthin) concentration in red and yellow table beets (Beta vulgaris L. ssp. vulgaris), respectively. Cycles of selection from both the red and yellow table beet breeding programs were evaluated for pigment and total dissolved solids (TDS) distribution in five tissue sections (outer, middle and center zones of the root; leaf and petiole) in two environments (early and late planting) during 2002. Betaxanthin concentration increased with the later planting date in the majority of the tissue zones in the yellow and red table beet populations. Absolute pigment concentration of the outer root zone increased the most over cycles of selection: 46.6 mg/100 g fresh weight (FW) betaxanthin and 201 mg/100 g FW betacyanin for yellow and red populations, respectively. However, the greatest rate of gain was in the center and middle tissue zones. Selection based on the outer 2 cm of root tissue has effectively increased pigmentation of the entire beet plant. A correlated response to selection in leaf and petiole tissue was measured for pigment concentration in both populations. The contribution of each tissue zone to total pigment concentration of the beet plant remained constant throughout cycles of selection averaging 39%, 25%, 25%, 6%, and 5% for outer, middle, center, petiole and leaf tissue zones, respectively. Across all table beet populations, pigment concentration of the outer root zone was 55% and 62% higher than middle and center zones, respectively. TDS of the outer root zone was 10% and 12% higher than middle and center zones, respectively.