Starch, growth, and development in cuttings of rootstock "Paulsen 1103" from plants infested with ground pearl.

ABSTRACT The ground pearl, Eurhizococcus brasiliensis, is considered an important pest of vineyards in southern Brazil, with affected plants exhibiting leaf chlorosis, reduction in vigor, fading, and death. This study evaluated the quality of hardwood cuttings produced from plants infected (I) and not infected (NI) by ground pearl. ?Paulsen 1103? (Vitis berlandieri × Vitis rupestris) plants were grown for 29 months in brick-built raised beds either infested or not infested by ground pearl; then, 12 one-year-old branches with a maximum of 12 buds each were cut from each plant, subdivided into three portions (4 buds cutting-1), and subjected to destructive and nondestructive testing. Destructive testing comprised determining fresh and dry weight, length, internode diameters, and percentage of starch. Nondestructive testing comprised assessing the potential for bud sprouting and shoot development. Each mother plant in the I and NI beds was considered a replicate, with a total of 360 cuttings per treatment. It was observed that cuttings from infected plants had significantly lower (P<0.05) internode diameter, length, and fresh and dry weight than those of the uninfected plants. The percentage of starch content of the cuttings did not differ significantly. All cuttings showed the same percentage (100%) of bud breaking and no changes in growth and development of seedlings regardless of source. Given these results, it was concluded that vines of ?Paulsen 1103? infested with ground pearl produce smaller cuttings than those of uninfected plants but with no reduction in bud break percentage or seedling development. Key words: Margarodidae, Vitaceae, insect?plant interaction, carbohydrates. RESUMO A pérola-da-terra, Eurhizococcus brasiliensis, tem sido considerada uma importante praga dos vinhedos no sul do Brasil, sendo que as plantas atacadas manifestam clorose foliar, redução no vigor, definhamento e morte. Este trabalho teve por objetivo avaliar a qualidade de estacas lenhosas produzidas a partir do contraste de videiras infestadas (I) e não infestadas (NI) por pérola-da-terra. Após 29 meses de cultivo em canteiros de alvenaria, em presença ou ausência de pérola-da-terra, cada planta da variedade ?Paulsen 1103? (Vitis berlandieri × Vitis rupestris) foi submetida à retirada de 12 ramos de ano, com no máximo 12 gemas cada, sendo subdivididos em três porções 4 gemas estaca-1) e submetidos a avaliações destrutivas e não destrutivas. As destrutivas consistiram em determinar massas fresca e seca, comprimento, diâmetro de entrenós e percentual de amido. As avaliações não estrutivas consistiram em testar o potencial de brotação e desenvolvimento das estacas. Cada planta matriz dos canteiros I e NI foi considerada uma repetição, totalizando 360 estacas por tratamento. As estacas das plantas infestadas tiveram uma redução (P<0,05), em relação às não infestadas, em diâmetro, comprimento e massas fresca e seca. Não houve contraste significativo do percentual de amido avaliado das estacas. Quanto à brotação, destaca-se que todas as estacas apresentaram o mesmo percentual (100%), independente da origem, sem alterações no desenvolvimento e crescimento das mudas. Diante desses resultados, salienta-se que videiras ?Paulsen 1103? infestadas por pérola-da-terra produzem estacas menores, porém não há comprometimento no percentual de brotação e desenvolvimento das mudas, quando comparadas com plantas não infestadas. Palavras-chave: Margarodidae, Vitaceae, interação inseto-planta, carboidrato

Growth and symbiosis of plants with arbuscular mycorrhizal fungi in soil submitted to biochar application.

Arbuscular mycorrhizal fungi (AMF), which is intrinsically present or may be introduced in soils by inoculation, is an example of natural and renewable resource to increase plant nutrient uptake. This kind of fungi produces structures (hyphae, arbuscles and sometimes vesicles) inside the plant root cortex. This mutualistic relationship promotes plant gains in terms of water and nutrient absorption (mainly phosphorus). Biochar can benefit plant interaction with AMF, however, it can contain potentially toxic compounds such as heavy metals and organic compounds (e.g. dioxins, furans and polycyclic aromatic hydrocarbons), depending on the feedstock and pyrolysis conditions, which may damage organisms. For these reasons, the present work will approach the impacts of biochar application on soil attributes, AMF-plant symbiosis and its responses in plant growth and phosphorus uptake. Eucalyptus biochar produced at high temperatures increases sorghum growth; symbiosis with AMF; and enhances spore germination. Enhanced plant growth in the presence of high temperature biochar and AMF is a response of root branching stimulated by an additive effect between biochar characteristics and root colonization. Biochar obtained at low temperature reduces AMF spore germination; however it does not affect plant growth and symbiosis in soil.

Isolation of micropropagated strawberry endophytic bacteria and assessment of their potential for plant growth promotion.

Twenty endophytic bacteria were isolated from the meristematic tissues of three varieties of strawberry cultivated in vitro, and further identified, by FAME profile, into the genera Bacillus and Sphingopyxis. The strains were also characterized according to indole acetic acid production, phosphate solubilization and potential for plant growth promotion. Results showed that 15 strains produced high levels of IAA and all 20 showed potential for solubilizing inorganic phosphate. Plant growth promotion evaluated under greenhouse conditions revealed the ability of the strains to enhance the root number, length and dry weight and also the leaf number, petiole length and dry weight of the aerial portion. Seven Bacillus spp. strains promoted root development and one strain of Sphingopyxis sp. promoted the development of plant shoots. The plant growth promotion showed to be correlated to IAA production and phosphate solubilization. The data also suggested that bacterial effects could potentially be harnessed to promote plant growth during seedling acclimatization in strawberry