Eficiência de fungos ectomicorrízicos na absorção de fósforo e na promoção do crescimento de eucalipto

Abstract

Resumo -O potencial de fungos ectomicorrízicos na promoção do crescimento das plantas e o controle da micorrização podem alavancar a exploração comercial desses fungos. O objetivo deste trabalho foi avaliar a eficiência de isolados de fungos ectomicorrízicos na colonização radicular, absorção de P e no crescimento de mudas de Eucalyptus dunnii, sob diferentes doses de fósforo. O inóculo dos isolados fúngicos INRA-Cou (Paxillus involutus), UFSC-Hg93 (Hysterangium gardneri), UFSC-Pt116 (Pisolithus microcarpus) e UFSC-Ch163 (Chondrogaster angustisporus) foi produzido assepticamente numa mistura turfa-vermiculitameio de cultura. As plantas foram cultivadas num substrato de igual composição, suplementado com macro e micronutrientes, e diferentes doses de fósforo: 0, 0,25, 0,50, 1,00, 2,00, 4,00 e 8,00 mg por planta. Os isolados UFSC-Pt116 e UFSC-Ch163 promoveram maior colonização radicular, absorção de P e crescimento das plantas, medido pela altura e massa de matéria seca. A colonização micorrízica foi inibida pelo aumento das doses de fósforo. As doses de 0,50 e 1,00 mg de P por planta mostraram-se mais adequadas em compatibilizar a colonização radicular com um bom crescimento das mudas. Os isolados UFSC-Ch163 e UFSC-Pt116 são promissores em um programa de micorrização controlada de E. dunnii. Termos para indexação: Eucalyptus dunnii, Pisolithus microcarpus, Chondrogaster angustisporus, ectomicorrizas, inoculação. Efficiency of ectomycorrhizal fungi on phosporus uptake and eucalypt growth promotionAbstract -The potential of ectomycorrhizal fungi to promote plant growth and the mycorrhization control may contribute to important progress towards the exploitation of these fungi commercially. The objective of this work was to evaluate the efficiency of ectomycorrhizal isolates on root colonization, P uptake and growth of Eucalyptus dunnii seedlings under different levels of phosphorus applied. Inocula of the ectomycorrhizal isolates, INRA-Cou (Paxillus involutus), UFSC-Hg93 (Hysterangium gardneri), UFSC-Pt116 (Pisolithus microcarpus) and UFSC-Ch163 (Chondrogaster angustisporus), were aseptically produced in a peat-vermiculite mixture supplemented with liquid culture medium. Plants were grown in a similar substrate supplemented with macroand micronutrients, under different levels of phosphorus: 0, 0.25, 0.50, 1.00, 2.00, 4.00, and 8.00 mg per plant. The isolates UFSC-Pt116 and UFSC-Ch163 promoted higher root colonization, higher P uptake and plant growth, as determined by plant height and dry matter. Levels of 0.50 and 1.00 mg of P per plant promoted a significant mycorrhizal colonization and an adequate plant growth. The isolates UFSC-Ch163 and UFSC-Pt116 represent a promising alternative for a controlled mycorrhization programme of E. dunnii.

Growth and Nutrition of Eucalypt Rooted Cuttings Promoted by Ectomycorrhizal Fungi in Commercial Nurseries

“…The increase in eucalypt CD, SH, and SDM promoted by inoculation with increasing application rates of different EMF species (Figures 1a, 1b, 1c) was also observed by other authors in eucalypt seedlings (Alves et al, 2001;Souza et al, 2004Souza et al, , 2008. E. dunnii seedlings had greater CD (1.4 times), SH (1.3 times), and SDM (1.7 times) levels when inoculated with Pisolithus sp.…”

“…Ectomycorrhizal fungi species differed in their capacity to increase leaf P concentration and content ( Figures 2a, 2b); however, they did not differ in terms of growth promotion (Figures 1a, 1b, 1c) and root colonization ability (Figure 1d), and they also raised leaf K and N concentration and content (Figures 2c, 2d, 2e, 2f). This similar behavior among EMF species observed in growth promotion, root colonization, and plant nutrition for some nutrients differs from most studies found in the literature (Alves et al, 2001;Silva et al, 2003;Souza et al, 2004Souza et al, , 2008Chen et al, 2006c).…”

“…E. dunnii seedlings had greater CD (1.4 times), SH (1.3 times), and SDM (1.7 times) levels when inoculated with Pisolithus sp. (UFSC-Pt24) (Souza et al, 2008), with P. microcarpus (UFSC-Pt116) isolate (1.2 times), and with C. angustisporus (UFSC-Ch163) isolate (1.3 times) (Souza et al, 2004). These results are greater than or equal to the CD and SDM observed in this study, which were 1.1 and 1.2 times higher respectively, always at the highest application rate without reaching a maximum (Figures 1a, 1b, 1c).…”

“…The authors observed a total dry matter increase up to 1.6 times for E. urophylla and two times for E. globulus compared to non-inoculated seedlings. Chondrogaster angustisporus and Pisolithus microcarpus vegetative inoculum in Eucalyptus dunnii increased the percent colonized root length, P uptake and shoot dry mass (SDM) of colonized plants (Souza et al, 2004). E. dunnii inoculated with Pisolithus sp., grown in a mixture with vermiculitepeat culture medium, had greater colonization at the highest inoculum rate (10 % in sapling substrate), whereas shoot height, diameter, and SDM increases were observed as of a 3 % inoculum rate and greater P concentrations as of 1 % (Alves et al, 2001).…”

“…especially in greenhouses (Courty et al, 2010) and with seminal saplings (Alves et al, 2001;Souza et al, 2004;Chen et al, 2006c). The development of this biotechnology for routine inoculation in commercial nurseries may increase the sustainability of planted forests in Brazil, making the already competitive forestry sector even more competitive.…”