BRESSAN, WELLINGTON.
EMBRAPA Milho e Sorgo, Department of Microbiology, P.O. Box 151, 35701 - 970, Sete Lagoas, MG, BRAZIL.
The effects of P and N amendement and its interactions on spore germination, root growth and colonized root length by Glomus etunicatum were studied " in vitro" in RiT - DNA transformed roots of Anthylis vulneraria. Three N media concentrations ( 5, 10 and 50 mg. l-1 ) at a constant P level ( 2 ml. l-1 ) and three P media concentrations ( 2, 10 and 20 mg. l-1 ) at a constant N level ( 5 mg. l-1 ) were utilized as treatments. Bécard & Fortin (1988) medium was used as a basal medium for root growth and colonized root length, and water / agar ( 0,8 % ) media was the control for spore germination. Spore germination of Glomus etunicatum at low P level was supressed by N addition in relation to the control media, and at low N level addition of P estimulated spore germination, but no significant difference ( p < 0.05 ) was observed between the control and the addition of 20 mg. l-1 of P. Total root length was stimulated by N addition at low P level, but no significant difference ( p < 0,05 ) was observed between 10 and 50 mg. l-1 of N. P addition at low N level media also stimulated total root growth, and a significant difference ( p < 0,05 ) was observed among P concentrations. Colonized root length by Glomus etunicatum increased significantly ( p < 0,05 ) with P additions at low N levels. Under low P level no significant differences were found between 10 and 50 mg. l-1 of N. These results demonstrate that the interaction between P and N affects spore germination, root growth and colonized root length in different ways.
Key words: Mycorrhiza - spore germination - root colonization - Glomus etunicatum.