THE EFFECTS OF MYCORRHIZAL INFECTION ON COMPONENTS OF PLANT-GROWTH AND REPRODUCTION

We studied the effects of mycorrhizal infection by Glomus etunicatum Becker & Gerd. and P amendment (three levels) on growth and reproduction of Abutilon theophrasti Medic. Mycorrhizal infection increased total leaf area, but individual leaf size was more affected than Leaf number. Mycorrhizal infection decreased the time taken to initiate flowering, increased the total duration of flowering, and increased seed production by increasing the number of flowers produced, the proportion of flowers producing fruits, and the number of seeds per fruit. Seeds produced by mycorrhizal plants were also heavier and contained more N and P than those produced by nonmycorrhizal plants. P amendment generally had similar influences to mycorrhizal infection, but seed P content was far more plastic in response to P amendment than to mycorrhizal infection. The various components of reproduction were not uniformly affected by either mycorrhizal infection or P amendment. The most phenotypically plastic reproductive components were fruit production and seed P content. The least plastic components were seed weight and seed N content.