Middle-East Journal of Scientific Research 6 (6): 604-611, 2010 ISSN 1990-9233 © IDOSI Publications, 2010 Effect of Phosphorus Fertilization on Arbuscular Mycorrhizal Colonization of Zeyheria tuberculosa a Native Species in Brazil’s Forest 12Marcela Claudia Pagano and Maria Rita Scotti 1Institute of Biological Sciences, Federal University of Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, 31270-901, Belo Horizonte, MG, Brazil 2Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil Abstract: A greenhouse experiment was done to assess the mycotrophy in native soil of Zeyheria tuberculosa, a tree with potential use in recuperation of degraded tropical lands throughout agroforestry and agrosilvopastoral systems. The effects of triple superphosphate fertilization on the growth and colonization of this species were evaluated. The fertilized seedlings presented higher height and dry matter. Acaulospora, Gigaspora, Glomus, Scutellospora and Racocetra were recorded at both conditions (fertilized and unfertilized); however, the rhizosphere of Z. tuberculosa was found to be dominated by Glomus. The higher percentage of root colonization as well as the presence of arbuscules and other arbuscular mycorrhizal (AM) structures confirmed that Z. tuberculosa is an AM plant. Key words: Arbuscular mycorrhizal fungi Tropical tree species Phosphorus fertilization Zeyheria tuberculosa Agroforestry INTRODUCTION uptake by the host plant under P limiting conditions. The extraradical AM hyphae can extend beyond root P Arbuscular mycorrhizas (AM) occur in most vascular depletion zones, thereby improving P uptake by plants; however, there are species less susceptible to AM mycorrhizal plants [7]. Moreover, AM increase the uptake colonization or that are not dependent of symbioses for of other nutrients, the tolerance to drought and the growth [1]. For the more susceptible species, the low resistance to transplantation stresses of seedlings [8]. nutrient availability found in tropical soils favors these Nowadays, there is a need to optimize nursery associations, which are frequently necessary for their practices to meet the demand for high quality seedlings optimal growth [2-4]. for outplanting and to understand the effects of Phosphorus (P) is a major limiting nutrient for plant interactions between AM species [1]. In nursery productivity, mainly because of its low mobility in soil. experiments non-pasteurized soil has been less used [9], Phosphorus might be present in large amounts in soil, but as the common nursery practice of soil sterilization may be the preferred form for assimilation, orthophosphate, is detrimental because it eliminates beneficial AM; besides, usually depleted owing to adsorption to soil particles or species not native to the site may not survive because conversion into organic complexes [5]. In tropical areas, they may not be adapted to the local pathogens [10]. soil P deficiency is one of the limiting factors for plant Fertilization and nutrient supply imbalance, especially growth because of slow diffusion through the soil [6] and higher levels of nitrogen (N) and P, are important factors plants have evolved various strategies for obtaining and influencing AM sporulation, which could be reduced recycling P. Different plant genotypes express these under those conditions [1]. Furthermore, different AM strategies in varying degrees, one such strategy being the species can show different responses to fertilization. For association with AM [5]. example, the relative abundance of Glomus intraradices Mycorrhizas benefit both partners and the main increased in response to fertilization, while it decreased effect of AM colonization is an increase in phosphorus for Gigaspora and Scutellospora species [11]. Corresponding Author: Marcela Claudia Pagano, Department of Biology, Federal University of Ceará, Campus do Pici, Bloco 902, 60455-760, Fortaleza, Ceará, Brazil Mobile: 0055 85 81064060, E-mail: [email protected], [email protected]. 604 Middle-East J. Sci. Res., 6 (6): 604-611, 2010 Moreover, Bhadalung et al. [12] showed that some rice husk, tanning curral manure and 20 mg P/kg substrate, spores of Glomus were classified as slightly sensitive to as single superphosphate (SSP). fertilization and others, as highly sensitive. Due to the On the other hand, Zangaro et al. [19] reported Z. difficulty in making specific fertilization recommendations, tuberculosa as a non-mycorrhizal (NM) plant and, the study of native plants needs to be fostered. Although consequently, in their review, Wang and Qiu [20] mention reports of plant species from Brazil have been recently this species as NM. The experiment by Zangaro et al. [19] increasing because of their importance for reforestation was carried out in a greenhouse in plastic bags filled with and restoration purposes, further research is needed to a mix of subsoil and sand (85:15), inoculated or not with investigate the differential colonization of different plant spores of native AM fungi. These were obtained from successional groups by AM fungi [13]. rhizosphere soil of different native tree species in an area Zeyheria tuberculosa Bureau (“bolsa de pastor”, with natural vegetation dominated by woody pioneer “ipê-felpudo”) is a semi-deciduous full-sun plant, endemic species, in the southern Brazilian State of Paraná. They to Brazil and threatened by habitat loss. Mostly used as found 0% of colonization at both inoculated and non- a timber and urban tree, this plant can be intercropped inoculated treatments. with other species in the agroforestry systems in One of the purposes of the present study was, Brazil [14]. Zeyheria tuberculosa is a pioneer tree with therefore, to clarify the Z. tuberculosa – AM association; relatively fast growth (mean annual increment reaches up this involved an experiment in plastic bags. As plant to 24m31 ha a year [14] and potential use in interactions with soil microbes vary with abiotic factors, recuperation of degraded lands. This is an invasive a fertilization treatment was also included. species in grasslands and degraded areas (pioneer We evaluated the mycorrhizal colonization of anthropic), which forms natural, pure populations. This Z. tuberculosa in a natural soil. An additional aim in our study was to indicate the potential AMF species as species presents monopodial growth (forming straight inoculants for Z. tuberculosa, a native species which trunk up to 2/3 of the total tree height) and natural presents ecological and environmental interest for Brazil. pruning; it can be included, in monoculture or mixed with other tolerant species, in agroforestry as well as in MATERIALS AND METHODS agrosilvopastoral systems [15]. Highly positive features, such as sprouting of the coppice after successive cutting Soil Properties: A clay “cerrado” soil extracted from a at different ages, broad leaves (50 to 90 cm length in secondary forest area in the surroundings of the city of seedlings and 30 to 40 cm in trees) and caducifoly (in July Belo Horizonte, Brazil, was used as substrate. The soil to September, when produces their fruits), may contribute was passed through a 2 mm sieve before being packed towards more sustainable agroecosystems [16]. 3 into bags of 1.7 dm capacity. The soil was analyzed at the Thus, Z. tuberculosa could be considered as a good soil Institute of Agronomy of Minas Gerais- Agropecuary protector because it has standing biomass along most of Chemical Laboratory, Brazil. Organic matter and P were the year, is broad-leaved and could benefit by AMF, determined. Potassium (K), calcium (Ca) and magnesium characteristics desired for restoration purposes. (Mg) were determined by atomic-absorption spectrometry Z. tuberculosa’s very hard wood (density 0.75 to using 1 N ammonium acetate as extracting solution. Soil 3 0.80 g/cm ) is good for manufacturing furniture, heavy texture was determined by the hydrometer method and the construction, parquet flooring, wheels and for use in pH of the soil was measured in H2 O. Exchangeable farm activities (posts, pillars, fences, wooden handle aluminum (Al) was extracted with 1 M KCl solution and tools, etc.). Its wood density is similar to that presented determined by titration with NaOH. by commercial “ipês” (Tabebuia and Paratecoma) [17]. Little is known about the nutritional requirements for Plant Material and Treatment: Seeds of Zeyheria this plant species and its AM status has been previously tuberculosa Bureau (Bignoniaceae) were collected from showed in nursery conditions by Carneiro et al. [18], who mature plants (forest fragments) located in Taquaraçú de observed low root colonization (1 to 19%). However, the Minas (19° 40’S 43°41’W) – State of Minas Gerais, Brazil. authors attributed the low colonization to the fact that soil After sterilization with mercury bichloride (HgCl2 ) 10% fumigation (methyl bromide) eliminates propagules of for 1 min, the seeds were placed in sterilized sand and AMF and that there was later a contamination of were watered with sterilized water for 7 days. Ten pre- seedlings, which were cultivated in bags on the soil. The germinated seeds of Z. tuberculosa were sown into each authors used bags containing 1 kg of substrate charred 24 bags. 605 Middle-East J. Sci. Res., 6 (6): 604-611, 2010 Fertilization of triple superphosphate (TSP) (P25 O ) Department of Plant Pathology, University of Agriculture was applied based on nutrient tests for native in Szczecin, Poland and the original species descriptions. trees. Phosphorus addition