Alessandro Carlos Mesquita

Anatomical characteristics and enzymes of the sucrose metabolism and their relationship with latex yield in the rubber tree (Hevea brasiliensis Muell. Arg.)

Rubber production is dependent on the availability of carbohydrates in the tissues engaged in latex synthesis. In this study three rubber tree clones were used to study the protein profile, the activities of invertase and sucrose synthase in the latex and anatomical characteristics of the bark, as well as to establish a possible relationship with latex production. The clones used in the study, RRIM 600, GT 1 and Fx2261, differed in latex productivity, from high to low in this order. Although present, few differences were observed in the latex protein profile obtained by denaturing electrophoresis. The activity of neutral invertase was higher than the acidic isoform, and both activities were higher in the most productive clones RRIM 600 and GT 1. The same was observed for sucrose synthase but it is suggested that invertase may play a more important role in sucrose cleavage in the latex. The anatomical measurements showed that the number of lactiferous cells and lactiferous rings per mm2, and lactiferous cell diameter were higher only in the most productive clone RRIM 600. Together, invertase activity and anatomical measurements might be useful to distinguish highly productive rubber tree clones.

Alterações morfofisiológicas em folhas de cafeeiro (Coffea arabica L.) consorciado com seringueira (Hevea brasiliensis Muell. Arg.)

One alternative to reduce the effects of the production instability and of the insecurity of world budget over coffee growers is the cultivation of rubber tree intercropped with coffee. However, the productivity of both cultures is affected strongly by the climatic variations and for the crop system. The objective of this research was to perform evaluations of gas exchanges, chlorophyll fluorescence (Fv/Fm ratio) and leaf anatomy of coffee trees in cropped in different systems with rubber tree and environment. Four intercropping systems were studied as described: full sun coffee (C), three coffee cultivation lines between double strip of rubber tree (SSCCCSS), one coffee cultivation line between rubber tree strips (SCS) and three coffee plants for one rubber tree in the same cultivation line (SCSCS). The coffee plants of the (SSCCCSS), (SCS) and (SCSCS) systems showed smaller values of net photosynthesis rate (A), stomatal conductance (gs) and transpiration (E) and highest values of Fv/Fm ratio than that observed for the (C) system. The coffee plants cropped in the (C) system presented the highest average leaf thickness and also the largest thickness of palisade and lacunar parenchymas and stomatal index. These results indicate that coffee leaves have a great anatomic plasticity when cropped at full sun light or under shaded caused by rubber trees.

Similaridade genética entre clones de seringueira (Hevea brasiliensis), por meio de marcadores RAPD

A seringueira [Hevea brasiliensis (Willd. ex. Adr. de Juss) Muell.-Arg.] e uma especie nativa da regiao amazonica e compreende a maior fonte produtora de borracha natural do mundo. Na busca de condicoes mais favoraveis ao cultivo, alem da busca pela auto-suficiencia na producao de borracha natural, o cultivo da seringueira migrou para outras regioes do pais. Objetivou-se, com o presente trabalho, estimar a similaridade genetica de genotipos de seringueira, provenientes de regioes distintas do pais, Lavras-MG (UFLA) e Campinas-SP (IAC), por meio de marcadores moleculares RAPD. A analise foi efetuada em 41 individuos, representados por 17 genotipos diferentes, com base em 19 primers, que geraram 121 fragmentos polimorficos. Os dados foram analisados utilizando o software NTSYS-pc - 2.1, por meio do coeficiente de Dice e pelo metodo das medias (UPGMA). A similaridade genetica entre o material analisado variou de 0,56 a 1,00. Na analise do dendrograma, foram observados 18 grupos. Os clones (RRIM600, GT1, PB235, PL PIM e FX2261), utilizados em diferentes repeticoes, foram identicos, quando comparados entre si, entretanto o mesmo nao foi observado para os clones identificados como RRIM 701. Os resultados obtidos sugerem que o material avaliado na UFLA e o mesmo implantado no IAC, exceto o RRIM 701, mostrando uma ampla variabilidade genetica, disponivel para estudos e propagacao da cultura.

Sazonalidade da produção e características do látex de clones de seringueira em Lavras, MG

In spite of being the cradle of the species of the genus Hevea, Brazil contributed, in 2001, with only 1.5% of the world production of 7.132 million tons and it consumed around 3.5% of a total of 7.03 million tons of the world demand. The most productive clones are the orientals RRIM 600, PB 235 and PR 255, with production around 1,500 kg of dry rubber/ha/year. The cultivation of those clones in different regions in Brazil shows adaptation to several climatic patterns. The aim of this work was to evaluate the productive behavior of clones of rubber tree, associated to seasonal climatic and physiologic factors in relation to the latex production in Lavras, State of Minas Gerais, Brazil. The research was conducted in the experimental area of Biology Department of Federal University of Lavras, sector of Plant Physiology, between June 2001 and July 2003. The plant water relations and nutritional factors were appropriate to the productive period. The productivity of clone RRIM 600 was higher than the others and presented positive correlation to the environmental factors during the experimental period. The nutritional factors of the latex and the obstruction index showed significant correlation to the production.

Growth, biophysical parameters and anatomical aspects of young rubber tree plants inoculated with arbuscular mycorrhizal fungi Glomus clarum

Mycorrhizal fungi are beneficial when associated with plants because they favor growth and develop. Although infrequent, artificial inoculation of arbuscular mycorrhizal fungi (AMF) has become an alternative to reduce the use of fertilizers and pesticides in crops, as well as for the formation of seedlings, to obtain precocious and well fed rootstocks. The objective of the study was to evaluate the effect of inoculation of AMF Glomus clarum on growth and biophysical and anatomical characteristics of young rubber trees. The treatments consist of plants inoculated with the fungus Glomus clarum and fertilized with 50 ppm of phosphorus (mic+50P), non-inoculated plants fertilized with 50 ppm of phosphorus (s/mic+50P) and non-inoculated plants fertilized with 500 ppm of phosphorus (s/mic+500P). The mycorrhizal plants showed height and stem diameter, dry matter accumulation of the aerial part, stomatal density and leaf area similar to the plants s/mic+500P. Greater accumulation of dry matter in the roots, higher transpiration rate, less stomatal resistance and lower leaf temperature were reported for the mycorrhizal plants. The anatomical analyses of the roots showed alterations in the vascular tissue, with increase in the number of xylem poles in the mycorrhizal plant roots.

Caracteristicas anatômicas da casca e produção de látex em plantas de seringueira não enxertadas

The structures involved in latex production in rubber trees are articulated laticifers. The objective of this study was to describe anatomical aspects of the bark in four, six and eight year old non-grafted rubber plants, with the view of selecting materials of high yield potential. The analyzed material was obtained from bark cut around 1.50 m from the soil up to the xylem of the plant. The transversal cuts were prepared according to standard plant microtechniques. Based on the results, we can conclude that the use of anatomical characteristics (cell diameter), bark thickness and shoot diameter for selecting material from rootstocks plus non-grafted plants of different ages, showed a significant correlation with latex production.

Assimilação metabólica de nitrogênio em plântulas de seringueira cultivadas com nitrato ou amônio

The objective of this work was to evaluate metabolic assimilation of nitrogen in rubber tree seedlings grown with nitrate or ammonium, by quantifying the activity of the enzymes nitrogen reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH). The following treatments were evaluated: nitrogen sources - control, without N application; 8 mmol L-1 ammonium; and 8 mmol L-1 nitrate -, and exposure times - 0 and 27 days -, in a 3x2 factorial arrangement, in a completely randomized block design with four replicates. The ammoniacal form favored higher N metabolic assimilation, which lead to a higher aminoacid accumulation. Both nitrate and ammonium assimilations occurred mainly by GS/GOGAT route; part of the nitric nitrogen is assimilated in the roots, with little GDH participation, and the other part is translocated to other organs. Ammonium nitrogen is totally assimilated in roots, with a significant participation of GDH. In the leaves, GS participates in the primary assimilation, as well as in the photorespiratory ammonium re-assimilation, irrespective of the N source, while GDH has a secondary role, independently of the source or of the exposure time. In vitro RN activity is detected only in the roots and stems.

Variação sazonal de algumas características nutricionais e bioquímicas relacionadas com a produção de látex em clones de seringueira [Hevea brasiliensis (Wild.) Muell. Arg.)], em Lavras-MG

Objetivou-se com este trabalho avaliar os efeitos das variacoes climaticas sazonais sobre a producao de latex, a partir de parâmetros relacionados ao fluxo e regeneracao de latex e da caracterizacao bioquimica dos tecidos fonte e dreno, com base nas atividades das enzimas invertase neutra e sintase da sacarose (SuSy). Foram usados foliolos centrais de folhas completamente expandidas de clones de seringueira (RRIM 600, FX 2261 e GT 1) nos meses de dezembro de 2001 e julho de 2002, plantados no Setor de Fisiologia Vegetal da Universidade Federal de Lavras (UFLA). Os dados de producao foram obtidos nos respectivos meses, por meio de sangrias no sistema S ½ (D2/D3), alem da utilizacao de borracha seca em estufa para analises minerais. Pelos dados de producao, verificou-se uma superioridade do clone RRIM 600 sobre os demais e um comportamento semelhante entre os outros clones, apresentando valores superiores no mes de dezembro. Para as caracteristicas bioquimicas avaliadas, as atividades de ambas as enzimas foram superiores no mes de dezembro em todos os clones, sendo mais representativas nos foliolos do clone RRIM 600. Todos os clones apresentaram valores superiores de acucares redutores e acucares soluveis totais em dezembro. Os teores de aminoacidos no clone RRIM 600 foram estatisticamente superiores em julho, ao passo que para os demais clones, esses nao diferiram. Os teores de proteinas totais foram superiores no mes de dezembro nos clones RRIM 600 e GT 1, sendo no mes de julho para o clone FX 2261. As analises minerais (N, Pi, Ca e Mg) da borracha seca demonstraram valores inferiores no mes de julho para todas as caracteristicas avaliadas. O clone GT 1 apresentou maiores valores de nitrogenio total, e os teores de Pi, Ca e Mg foram superiores na borracha seca do clone FX 2261.

Atividade da rubisco e das enzimas de síntese de hidrólise de sacarose, associada à produtividade de látex , em clones de seringueira [ Havea brasiliensis (Willd ex. Adr. de Juss.) Muell.-Arg] cultivados em Lavras, MG

Estudos ja realizados sobre clones de seringueira cultivados no estado de Minas Gerais tem fornecido indicios que permitem supor a existencia de uma possivel associacao entre a variabilidade fotossintetica e a producao de latex. Contudo, ainda e escasso o conhecimento acerca da assimilacao de CO2 e o transporte de carbono das folhas ate a casca, onde a biossintese de latex ocorre de forma mais intensa. Em todas as etapas desses metabolismos, as reacoes sao reguladas por algumas enzimas-chave. Este trabalho proposse a avaliar a atividade da Rubisco e das principais enzimas de sintese e hidrolise de sacarose, em plantas de um jardim clonal de seringueira pertencentes aos clones RRIM 600, GT 1 e FX 2261, e sua relacao com o desempenho produtivo de plantas adultas e em franca producao. Os resultados sugeriram uma provavel associacao entre a atividade da Rubisco e das invertases (acida e neutra) e o desempenho produtivo dos clones. Nao houve evidencias de tal associacao, em relacao a sacarose-fosfato sintase (SPS) e a sacarose sintase (SuSy), cujas atividades nao diferiram entre os clones avaliados. A hidrolise de sacarose na casca foi exercida predominantemente pela acao da invertase acida. Em proporcoes menores e equivalentes, essa atividade foi complementada pela SuSy e pela invertase neutra.

Bud load management on table grape yield and quality – cv. Sugrathirteen (Midnight Beauty®)

Bragantia, Campinas, v. 77, n. 4, p.577-589, 2018 ABSTRACT: Viticulture is an activity of great economic and social importance in the Submedium region of the São Francisco River Valley, with emphasis on table grape and wine production. With the increasing expansion of the viticulture, a growing number of alternatives that do not affect fruit quality have been studied to maximize table grape yield, such as pruning and load adjustment. The aim of the present study was to evaluate the influence of different bud loads on canopy management to enable the marketable and economic production of cv. Sugrathirteen (Midnight Beauty®) in the submedium region of the São Francisco River Valley. This study was carried out for two years (2014/2015) in an experimental area for the introduction of new cultivars patented by Prodomo Farm in the municipality of Petrolina, CROP PRODUCTION AND MANAGEMENT Article