Olmar Baller Weber

Isolation and characterization of diazotrophic bacteria from banana and pineapple plants

Banana and pineapple fruit crops are widely cultivated in tropical areas where high amounts of fertilizers are applied, principally nitrogen. Over 200 kg N.ha-1.yr-1 is often applied to these crops. Nevertheless, developing countries face the problem of high costs of chemical fertilizers. As already demonstrated for other tropical crops, like sugar cane, the utilization of nitrogen-fixing bacteria may support the growth of these fruit plants. In this work, we demonstrate the association of nitrogen-fixing bacteria with banana and pineapple. Samples from roots, stems, leaves and fruits of different genotypes showed the occurrence of diazotrophic bacteria, when evaluated in semi-specific semi-solid media. These isolates could be separated into seven different groups according to their morphological and physiological characteristics. Additional, phylogenetic assignments were performed with group- and species-specific oligonucleotide probes. Bacteria related to the groups of Azospirillum amazonense, Azospirillum lipoferum, Burkholderia sp. and a group similar to the genus Herbaspirillum could be detected in samples of both crops. However, Azospirillum brasilense and another two groups of Herbaspirillum-like bacteria were detected only in banana plants. Two isolates of the latter group were identified as Herbaspirillum seropedicae, whereas the other isolates may represent a new Herbaspirillum species.

Comprimento de estacas e parte do ramo na formação de mudas de aceroleira

The rhizogenic capacitity, sprouting and vigor of cuttings from barbados cherry (Malpighia emarginata D.C) were evaluated in greenhouse conditions at the EMBRAPA - National Center for Research of Tropical Agroindustry, Fortaleza-CE, from November 2000 to January 2001, aiming to identify the best branch part and size for cuttings preparation. The experiment was conducted in a completely randomized design, in a 3x3 factorial scheme, corresponding to three positions on the branch (apical, median and basal) and three length (10, 15 and 20 cm), with three replications composed by 10 cuttings each, and cultured on tubets of 288 cm3, filled wich a misture of organic matter (vermicompost) and carbonized rice husks (3:2 volumetric proportion), and cultivated in a greenhouse with intermittent mist. After 60 days were evaluated the percentage of surviving cuttings, rooted cuttings, roots and aerial part dry matter, number of leaves, not developed meristems, and number of new branches per cutting. Results indicated that vegetative propagation by cuttings of Barbados cherry is a feasible method, by using cuttings with 10 cm length, taken from the middle positions of the branch, and cultured under greenhouse conditions and intermittent mist.

Inoculação de fungos micorrízicos arbusculares e adubação fosfatada em mudas de cajueiro-anão-precoce

This work aimed to evaluate the effects of the inoculation of native and exotic arbuscular micorrhizal fungi (AMF) and of the phosphate fertilization on plant growth and nutrient accumulation in dwarf cashew CCP 76. A greenhouse experiment, using a factorial arrangement (4x2), with three mixtures (two native communities of AMF and the commercial Mycogold product) besides a control without fungi and two dosages of phosphorus (0 and 87 mg/L) was carried out. Native AMF were represented by the species Glomus etunicatum, G. glomerulatum, Scutellospora sp. and Acaulospora foveata, from the first community, and G. etunicatum, Entrophospora sp. and Scutellospora sp., from the second community. The cashew seedlings presented a low response to the phosphorus treatment. The symbiotic plant association with the native fungi of the first community and exotic fungi of the commercial product allowed a better plant growth four months after cashew nut sown.

Efeito da bactéria diazotrófica em mudas micropropagadas de abacaxizeiros Cayenne Champac em diferentes substratos

Abstract – The objective of this work was to evaluate the effect of a diazotrophic bacteria isolated frompineapple ( Ananas comosus ) plants on plantlets growth and nutrient accumulation of the cultivarCayenne Champac grown with different substrates in tubules conditions. Treatments consisted of sixsubstrates: carbonized rice hulls + leave dust from carnauba ( Copernicia cerifera ) palm tree +vermicompost; carbonized rice hulls + rip coir dust + vermicompost; carbonized rice hulls + vermiculite +vermicompost; carbonized rice hulls + leave dust from carnauba palm tree + vermiculite; carbonizedrice hulls + ripe coir dust; and carbonized rice hulls + vermiculite. The bacterium isolate was identifiedby similarity (97% to 98%) of sequences of 16S rDNA with the species Asaia bogorensis. After thebacterial inoculation , plants were transferred to substrates into tubules conditions. After four months,at harvesting, acclimated plants were ready to be planted in the field. The occurrence of diazotrophicbacteria related to

HERBASPIRILLUM-LIKE BACTERIA IN BANANA PLANTS

Diazotrophic bacteria isolated from banana plants were characterized by morphological and physiological aspects. Three different groups of these plant-bacteria could be established. Two of them showed similarity to species of the Herbaspirillum genus. The third one was different because used only a few carbon substrates and produced water diffusible compounds that fluoresced under UV light. All three bacterial groups were thin rods with mono or bipolar flagella, presented negative reaction in Gram stain, showed catalase activity, were able to reduce nitrate and grew better in semi-solid JNFb medium at 31oC. The nitrogenase activity was detected in semi-solid N-free JNFb medium and expressed higher values when pH ranged from 6.5 to 7.0 (groups I and II) and 6.0 to 6.5 (group III). The diazotrophs isolated from banana plants were distinct from species of Herbaspirillum previously identified in gramineous plants.

Resposta de plantas micropropagadas de abacaxizeiro à inoculação de bactérias diazotróficas em casa de vegetação

Response of pineapple plantlets to inoculation with diazotrophic bacteria in greenhouse Abstract - The objective of this work was to select and to evaluate isolates of diazotrophic bacteria associated to pineapple (Ananas comosus (L.) Merril) plants in the development of micropropagated plantlets of cultivars pineapple in greenhouse. Plantlets from the Perolera cultivar have been submitted to inoculation with Asaia bogorensis (AB219) and were cultivated during 145 days on the following mixtures: carbonized rice hulls, leave dust from carnauba (Copernica cerifera) palm tree, vermicompost; carbonized rice hulls, rip coir dust, vermicompost; and carbonized rice hulls, vermiculite, vermicompost. Plantlets of the Primavera cultivar had received bacterial inocules containing AB219 and bacteria related to Burkholderia cepacia (AB202 and AB213), while plantlets of Perola and Smooth Cayenne cultivars were bacterized with AB213 and AB219, and had been cultivated during 140 days on vermicompost and vermiculite mixture. The plant colonization by diazotrophs was confirmed. Plantlets of Perolera cultivar grew better on substratum with carbonized rice hulls, vermiculite and vermicompost and obtained benefits from AB219 bacterium. All diazotrophs did not improve significantly the biomass of the Primavera cultivar. Increment on root dry matter of Perola cultivar ranged from 23.1% to 38.5%, when AB213 and AB219 were applied, respectively. The AB213 isolate incremented 15.2% of dry matter in shoots of Smooth Cayenne cultivar. The results indicated the diazotrophic bacteria efficiency in promotion of pineapple plant growth.

Diagnose foliar da gravioleira (Annona muricata L.): efeito da posição de ramos e folhas

A carencia de informacoes na literatura sobre a amostragem de folhas da gravioleira, particularmente, a definicao da posicao da folha na copa das arvores e das folhas nos ramos ainda e um fator limitante para a diagnose foliar dessa cultura. Objetivando determinar a parte da planta indicada para a amostragem de folhas e a avaliacao do estado nutricional da gravioleira conduziu-se um experimento no Campo Experimental da Embrapa Agroindustria Tropical, em Pacajus (CE), no periodo de marco a abril de 2003. Colheram-se folhas de tres posicoes da copa (terco superior, terco medio e terco inferior) e tres posicoes no ramo (folhas da parte apical, mediana e basal) e determinaram-se os teores de P, K, Ca, Mg, S, Fe, Cu, Zn e Mn. Os resultados permitem sugerir que os teores de minerais das folhas da parte mediana da copa das arvores e na posicao mediana do ramo refletem melhor o estado nutricional da frutifera.

Teores de macronutrientes em mudas de aceroleira (Malpighia emarginata DC.) em função da composição do substrato

A composicao do substrato com diferentes fontes de materia orgânica e considerado como um elemento chave na obtencao de mudas de boa qualidade. Assim, com este estudo objetivou-se avaliar a melhor fonte e a melhor quantidade de materia orgânica que podera ser usada para a producao de mudas de aceroleira (Malpighia emarginata DC.) de boa qualidade. Um fatorial quatro (20:80, 40:60, 60:40 e 80:20% de materia orgânica:terra) por quatro (humus de minhoca, casca de arroz carbonizada, po de casca de coco seco e bagana de carnaubeira) niveis foi usado em delineamento em blocos casualizados com quatro repeticoes. O conteudo de nitrogenio, fosforo, potassio e calcio nas folhas e caules foram quantificados na materia seca das mudas. Os resultados demonstraram que a proporcao de 80% de humus:20% de terra permitiram bom desenvolvimento das plantas com niveis suficientes de N, P, K e Ca. Casca de arroz carbonizada, po de casca de coco seco e bagana de carnaubeira nao contribuiram para a obtencao de mudas de boa qualidade.

Variação sazonal da concentração de macronutrientes em folhas de diferentes genótipos de aceroleira

Plants of Barbados cherry (Malpighia emarginata) produces all over the year, and its fruits are rich in vitamins and minerals. In order to obtain good production and high fruit quality it is necessary to know the nutritional need and the suitable season for plant fertilization. Thus, it was carried out an experiment at the EMBRAPA-National Center for Research of Tropical Agro-industry, from December 1999 to October 2000, aiming to study the seasonal changes nutrient (N, P, K, Ca, Mg and S) levels, and the suitable period for leaves mineral diagnosis, in six genotypes P 52, P 66, P 78, P 91, P 93 and P 97) and six distinct sampling times. All the 36 treatments (six genotypes evaluated in six harvest times) were conducted in a Randomized Completed Block (RCB) design with, and analyzed statistically as a split plot, with four replications composed by one plant each. It was observed low variations on macronutrient levels in the leaves among genotypes. December is the most suitable period for leaves sampling aiming to plant nutritional diagnosis of Malpighia emarginata, at Ceara Estate, Brazil.

Biofertilizers with Arbuscular Mycorrhizal Fungi in Agriculture

An increase in crop production is essential to meet the future food demand. Agricultural systems should be sustained by maintaining soil fertility and soil structure by effective use of fertilizers with increased profitability and reduced harm to the environment. Other strategies involve application of ecological concepts and principles to the design, development, and management of sustainable agricultural systems. Microbial inoculants, including arbuscular mycorrhizal (AM) fungi and plant growth-promoting rhizobacteria, for increasing the efficient use of fertilizers are potential components of such management. AM fungal inoculants have been marketed as an important biological component to the commercial horticulture and agriculture. This review considers biofertilizers within the framework of fertilizer demand and use of AM fungal inocula.