Mycorrhizal dependency of papaya commercial varieties

Abstract

Plant genome is an important factor in plant response to arbuscular fungi. This work was designed to evaluate the degree of response to P application and mycorrhizal dependence of different varieties of papaya (Carica papaya L.). The experiment was performed under greenhouse conditions at Embrapa-Centro Nacional de Pesquisa de Mandioca e Fruticultura, Cruz das Almas, BA, Brazil, using seedlings of four varieties, six rates of P: 0, 20, 40, 80, 140 and 280 mg dm-3, and three fungi treatments (one control uninoculated and inoculation with Glomus clarum or Gigaspora margarita). The following parameters were estimated: rate of P for maximum mycorrhizal efficiency; T' value; P benefit, mycorrhizal benefit, symbiotic efficiency, and mycorrhizal dependence. Control plants had a quadratic response to applied P, while those inoculated had a root-quadratic response with a great increment in growth at lower rates; phosphorus benefit was higher in Sunrise Solo and Improved Sunrise Solo - Line 72/12 varieties, while the other two varieties showed a higher mycorrhizal benefit, resulting in a higher symbiotic efficiency. Papaya varieties showed the following classification of mycorrhizal dependency: Baixinho de Santa Amália = Tainung no 1 > Sunrise Solo = Improved Sunrise Solo - Line 72/12. Mycorrhizal dependence related with the capability of the variety to produce roots.