INFLUENCE OF ENDOMYCORRHIZAL INFECTION ON ROOT MORPHOLOGY IN A MICROPROPAGATED WOODY PLANT-SPECIES (VITIS-VINIFERA L)

The influence of vesicular-arbuscular (VA) endomycorrhizal infection on root morphology and architecture of a woody micropropagated plant, Vitis vinifera L., has been investigated using morphological analysis, modelling and topological methods. Endomycorrhiza formation caused increases in lateral root number and consequently total root length but did not alter the number of root axes. The rate of production of any order lateral roots was higher in mycorrhizal than non-mycorrhizal controls. The number of first- and second-order laterals increased linearly with time in mycorrhizal plants whilst in control plants both fitted a logistic function. Topological analysis indicated similar patterns of root branching in the early stages of growth, but the root system of non-mycorrhizal plants adopted a more herringbone pattern after 8 weeks, whereas that of mycorrhizal plants retained a more dichotomous pattern with repeated bifurcation. Although the root system pattern of non-mycorrhizal vines is more efficient in exploring soil, it is more expensive for the plant in terms of energy cost versus return benefit (nutrient acquisition). In contrast mycorrhizal plants develop a more economical root system which is rendered more efficient by the direct role of the mycorrhizal fungus in assisting nutrient absorption. © 1991 Annals of Botany Company.