Root yield and quality of sugar beet (Beta vulgaris L.) in relation to plant population

Introduction of genetic monogerm seed and the advancement of agricultural techniques raised the possibility of eliminating costly thinning operations in sugar beet farming. However, this requires high and uniform seedling emergence to provide prerequisite plant populations in the held. This work investigated the minimum levels of seedling emergence for non-thinned sugar beet farming. The experiment was carried out in a loamy soil to investigate the effects of three levels of emergence (60, 50 and 35%) and two intra-row spacings (8 and 15 cm) with or without thinning using seed source of graded viability of cv Eva in 1992 and 1993 under field conditions in Eastern Anatolia. Plant population throughout the growing period was monitored and data were taken of yield and quality parameters. On average, 60, 50 and 35% emergence levels were achieved using seed source of 90, 72 and 54% viability range, which resulted in different levels of plant stands depending on intra-row spacing and thinning. Plant density at harvest ranged between 49 500 and 124 500 ha(-1) on average depending on initial establishment, intra-row spacing and thinning. Root yield and sugar yield were the highest at plant stands between 90 000 and 100 000 ha(-1), below or above of which declined. Impurity contents (e.g. Na, K and a-amino N contents) and extractable sugar content decreased but sugar content and clear juice purity enhanced as plant stands at harvest increased.