Alleviation of drought stress of Chile ancho pepper (Capsicum annuum L. cv. San Luis) with arbuscular mycorrhiza indigenous to Mexico

Selecting indigenous mycorrhizal fungi that enhance plant water status is important in Mexico for sustainable production systems of Chile ancho pepper (Capsicum annuum L. cv. San Luis). To determine mycorrhizal enhancement of drought resistance, plants were either non-inoculated (NonAMF), or inoculated with arbuscular mycorrhizal fungi (AMF): Glomus fasciculatum and a mixed Glomus spp, from Mexico (ZAC-19). Plants were then exposed to a 20-day drought cycle. To equalize growth and minimize tissue-P differences, NonAMF plants received higher P than AMF plants. Drought reduced leaf water potential tissue relative water content (RWC), stomatal conductance (g(s)), whole plant transpiration (mg H2O m(-2) s(-1)), leaf transpirational surface area and plant biomass. Only plants colonized with ZAC-19 had enhanced drought resistance, as indicated by higher Psi(leaf) and fewest plants with visible wilting during peak drought stress. A higher root/shoot ratio occurred with ZAC-19 plants (despite equal total plant biomass among droughted plants), which may have also contributed to drought resistance. Drought enhanced arbuscule formation and hyphae development of ZAC-19, while reducing colonization of G. fasciculatum. Tissue P was not a contributing factor to drought resistance. AMF did not enhance water-use efficiency (WUE) as-determined gravimetric ally on a whole plant basis (g carbon/kg H2O) or by carbon isotope discrimination (Delta). (C) 2002 Elsevier Science B.V. All rights reserved.