ICOM1 Abstract

CHINNERY, LOUIS E. & LYNDON F. ROBERTSON. Department of Biology, The University of the West Indies, P.O.B. 64, Bridgetown, Barbados. - Using phytometers to assess the mycorrhizal potential of soils Soils were sampled from each of the ten soil associations of Barbados. At each site two subsamples were placed, with as little disturbance as possible, into 15cm plant pots and a third subsample bagged for subsequent spore extraction. Three seedlings each of corn (Zea mays), pepper (Capsicum annuum) and bean (Phaseolus vulgaris), germinated in autoclave sterilised growth media (soil:sand:vermiculite), were transplanted into one set of soil samples and 24hr pre-soaked corn achenes planted in the second set. Vesicular-arbuscular mycorrhizal (VAM) fungal colonisation of roots was determined 2, 3 and 4 wk after transplanting. Spore populations were low and varied between 1.02 and 2.63 g-1 soil with the lowest populations being found in the agriculturally most productive soil type. VAM colonisation increased with time and corn plants showed the greatest level of colonisation. Significant differences between VAM fungal colonisation of phytometer roots between soil types was closely related to spore density. This study has not shown that the use of phytometers provides a better assessment of the VAM potential of soils than counting spores.