Effect of sowing date on the performance of root chicory

Abstract

Root chicory is a potential alternative sugar crop which accumulates a high amount of linear fructose polymers (fructan) in its roots. Lengthening the growing season by early sowing may increase root chicory yield potential, and thus increase its competitiveness with traditional sugar crops. A field experiment was conducted in 1998 and 1999 on a sandy loam soil (Haplic Luvisol) at Braunschweig, Germany, to study the consequences of early sowing on emergence, bolting, yield, and quality of root chicory. In each year, the cultivars Tilda, Wixor, Hicor, Cassel, Bergues, Fredonia Nova, and Regalo were sown at three dates ranging from mid March to early May. The mean emergence rates for the early sowings in March were insufficient in 1998 (45%) but adequate in 1999 (82%). Averaged across years and cultivars, emergence took 25, 21, and 13 days at early, medium, and late sowing. While bolters were almost absent at medium and late sowing, average bolting percentage at early sowing amounted to 18.3% in 1998 and 22.7% in 1999. Each percent of bolters reduced fructose yield by 1.1% in 1998, and 1.2% in 1999. In 1998, the fructose yield of the most productive cultivars at early sowing (Bergues) and at medium sowing (Fredonia Nova) were not significantly different. In 1999, early sown Bergues produced a significantly higher fructose yield than any other cultivar and sowing date combination. It is concluded that increasing root chicory yield potential by early sowing is not limited by a lack of bolting-resistant cultivars, but by the risk of poor crop establishment due to unfavourable weather conditions.