Effect of Hydroelutriation on Nonstructural Carbohydrates in Fibrous Roots

Abstract

Hydroelutriation can reduce the time required to remove roots from soil cores relative to conventional washing methods. However, method of washing may affect subsequent chemical analysis. We compared a hydroelutriation method to dry, hand cleaning of roots for subsequent carbohydrate content of root tissue. Fibrous roots of winter wheat (Triticum aestivum L.), johnsongrass (Sorghum halepense (L.) Pers.), Caucasian bluestem (Bothriochloa caucasica (Trin.) C.E. Hubb.), and little bluestem (Schizachyrium scoparium (Michx.) Nash) were collected on 8 March and 25 May 1985. Roots were analyzed for both soluble carbohydrates and total nonstructural carbohydrates (TNC). Soluble carbohydrates were extracted using 2.5 mM H2 SO4; the TNC extraction included a 24-h incubation with amyloglucosidase at 50 degrees C in addition to weak acid hydrolysis. There were no significant differences (P>.05) between cleaning procedures for any of the species on the first sampling date, and only Caucasian bluestem roots were significantly affected (P<.05) by cleaning procedure the second date. Hydroelutriation washing resulted in a 15% reduction in both soluble carbohydrates and TNC in Caucasian bluestem roots relative to dry, hand cleaning. In general, loss of nonstructural carbohydrates from washed fibrous roots was not a major concern in the 4 species we tested. However, in specific instances it may be necessary to use a correction factor to account for loss of chemical constituents when using hydroelutriation methods.