Studies on the development of vesicular-arbuscular mycorrhiza in cowpeas (vigna unguiculata(L.) Walp)

The present study was undertaken to investigate the effect of host metabolism on fungus development. Cowpea (Vignaunguiculata (L.)Walp,), Sunflower (Mellianthusannus (L.) and fingermillet (Eleusinacoracana (L.)Gaertn.)were selected as test plants representing a leguminous and non-legumonous dicot and a monocot respectively. The source of in oculum in all experiments was an unsterilized sandy loan taken from a garden at Ubungo on the University of Dar Es Salaam main campus in which cowpea and rice had been grown for some years previously. The experimental period was from 29 June 1976 to 19 December 1976. Grown in pot cultures with unsterilized garden soil, the development of V-A mycorrhiza was studied. The resulting infection was attributed to a complex of fungi of which Gigasporagilmorei Trappe and Gerd may have been the predominant species. Chlamydospores of a Glomus sp. Were found on some roots of cowpea. In conclusion, it is proposed from the investigation that arbuscule development is inversely related to carbohdrate levels in the roots while vesicle formation seems to be directly related to nutrient availability. In addition, auxin appeared to stimulate arbuscule formation but had no effect on vesicles. Whether the hormone acts directly on the fungus or indirectly through nutrient supply or some other aspect of host metabolism remains uncertain and requires further investigation and assessment of auxin levels in the roots