Size and Reproductive Inequality in Mycorrhizal and Nonmycorrhizal Populations of Abutilon Theophrasti

Abstract

1 We grew Abutilon theophrasti Medic. with and without mycorrhizal colonization in the field at two plant densities both of which resulted in self-thinning of the populations. 2 There was an initial convergence of plant density from high and low sowing densities to a common density of plants. Thereafter, for both sowing densities log biomass increased and log density decreased along a biomass-density boundary that had a slope of during the period of greatest density-dependent mortality. 3 Size inequality among individuals decreased during the period of greatest densitydependent mortality because of greater mortality in the smallest size classes. 4 For the first 92 days, mycorrhizal colonization did not significantly alter the biomass-density relationship. 5 Mycorrhizal populations did not develop significantly different size inequality than nonmycorrhizal populations, but they did develop significantly greater inequality in fecundity. The proportion of individuals reaching reproductive maturity was similar in the two populations, but reproductive individuals in mycorrhizal populations had more capsules than those in nonmycorrhizal populations.