ESTIMATING ROOT LENGTH DENSITY AND BIOMASS IN ASPARAGUS

Abstract

Soil type, crop management practices, annual plant growth patterns and seasonal changes in the soil environment all influence asparagus roots. This study describes the changes that occur in root growth over time in two contrasting soils and crop management systems. Soil cores (5.5-cm diameter x 20-cm long) were collected to one meter in on six dates (pre/postharvest, early/mid/late fern growth, and dormant period) and in three locations (15/30/60 cm from row) in 1999-2000. Sites varied with soil (sandy loam or silt loam) and by crop management system (normal 12-week harvest or extended 15-week harvest). Fibrous and fleshy roots were collected and root length density determined. Soil type significantly altered rooting depth (sandy>silt), dry matter content (silt>sandy) and root length density (silt>sandy) of fleshy roots. Fibrous root length density varied with sampling date (harvest silt) and sampling depth (shallow>deep). Sampling date, soil depth and sample location significantly influence asparagus fleshy and fibrous root biomass. Soil cores accurately estimated both total fleshy root length density and dry matter content when compared to the more time consuming complete root excavation. Results can be used to improve crop management practices, predict root biomass and increase our understanding of the dynamics of root development in asparagus.