Root length and distribution of field-grown buckwheat (Fagopyrum esculentum Moench)

Abstract

We determined the seasonal changes in the root system of field-grown buckwheat (Fagopyrum esculentum Moench). Rooting soil volume was collected in 1 L soil blocks to a 40 cm depth, and roots were separated from soil by boiling. The root length was determined by the modified line intersect method. Root length increased constantly until peak flowering, then did not increase, reaching a value of 18.9 km m-2 at harvest, corresponding to a surface area of 4.1 m2 m-2 and an average length density of 4.7 cm cm-3. The fine root diameter decreased from 83 to 66 μm with the growth stage and the length/dry weight ratio increased from 849 to 1,199 m g-1. Root length density was highest in the 0-10 cm and/or 10-20 cm soil layers and decreased below this depth. Nutrient uptake per unit root length was highest at the early growth stage, 0.51 mg m-1 for N and highest at the flower budding to peak flowering stages, 0.12 mg m-1 for P. Constraints on methodologies such as debris removal and labor reduction were outlined. A field containing few debris must be selected for root studies because the removal of a large amount of debris is laborious.