Celso Jamil Marur

Expression of three galactinol synthase isoforms in Coffea arabica L. and accumulation of raffinose and stachyose in response to abiotic stresses.

Galactinol synthase (EC 2.4.1.123; GolS) catalyzes the first step in the synthesis of raffinose family oligosaccharides (RFOs). Their accumulation in response to abiotic stresses implies a role for RFOs in stress adaptation. In this study, the expression patterns of three isoforms of galactinol synthase (CaGolS1-2-3) from Coffea arabica were evaluated in response to water deficit, salinity and heat stress. All CaGolS isoforms were highly expressed in leaves while little to no expression were detected in flower buds, flowers, plagiotropic shoots, roots, endosperm and pericarp of mature fruits. Transcriptional analysis indicated that the genes were differentially regulated under water deficit, high salt and heat stress. CaGolS1 isoform is constitutively expressed in plants under normal growth conditions and was the most responsive during all stress treatments. CaGolS2 is unique among the three isoforms in that it was detected only under severe water deficit and salt stresses. CaGolS3 was primarily expressed under moderate and severe drought. This isoform was induced only at the third day of heat and under high salt stress. The increase in GolS transcription was not reflected into the amount of galactinol in coffee leaves, as specific glycosyltransferases most likely used galactinol to transfer galactose units to higher homologous oligosaccharides, as suggested by the increase of raffinose and stachyose during the stresses.

Características fisiológicas e de crescimento de cafeeiro sombreado com guandu e cultivado a pleno sol

The characterization of shade effects on the physiology of coffee is important to determine optimum levels of radiation and temperature, as well as to subsidize studies on growth of shaded plants aiming at determining the ideal coffee plant architecture that maximizes the capture of the available solar radiation in shaded environments. The objective of this work was to evaluate physiological and growth characteristics of coffee (Coffea arabica L.) shaded with pigeonpea (Cajanus cajan (L.) Millsp.) and under full sun. The low level of incident radiation on the coffee shaded with pigeonpea caused decreases in the photosynthetic rate and transpiration, increased plant height and leaf size, but diminished leaf dry matter. These results indicate that the excess of shade drastically affects the physiology and morphology of C. arabica.

Modifications on leaf anatomy of Coffea arabica caused by shade of pigeonpea (Cajanus cajan)

Adaptacoes de plantas da mesma especie aos diferentes habitats, constituem a base da diferenciacao entre folhas a pleno sol e folhas sob sombra e estao associadas a caracteristicas anatomicas distintas. Para caracterizar tais mudancas em cafeeiros cultivados sob sombra de guandu (Cajanus cajan) e a pleno sol, em Londrina, PR, foram realizadas avaliacoes de modificacoes ocorridas na anatomia foliar. As estruturas internas avaliadas foram: parede celular e cuticula; epiderme; mesofilo (parenquima palicadico, parenquima lacunoso e espacos intercelulares) e estomatos. Para todas as variaveis avaliadas observaram-se diferencas anatomicas entre folhas expostas ao sol e a sombra. As folhas expostas ao sol apresentaram cuticulas e paredes celulares mais espessas, celulas da epiderme mais estreitas, parenquima palicadico com celulas mais alongadas, parenquima lacunoso espesso e com poucos espacos intercelulares e maior numero de estomatos. Folhas sob condicoes de denso sombreamento apresentam menor espessamento da cuticula e da parede celular; mesofilos com menores volumes, porem com maiores espacos intercelulares; epidermes com celulas mais espessas e estomatos em menor quantidade, envoltos por celulas subsidiarias de menores dimensoes. Plantas cultivadas a pleno sol apresentam maiores taxas fotossinteticas. Assim, Coffea arabica caracteriza-se como uma especie com grande amplitude de adaptacao fenotipica as mudancas na intensidade de radiacao solar.

Desenvolvimento de plantas de algodão provenientes de sementes embebidas em cloreto de mepiquat

O efeito da embebicao de sementes de algodao cultivar IPR-120 com cloreto de mepiquat no crescimento e desenvolvimento inicial das plantas foi avaliado em casa de vegetacao. Os tratamentos foram arranjados em esquema fatorial 5x3 (cinco concentracoes do produto, tres tempos de embebicao), com cinco repeticoes. Altura e area foliar foram avaliadas, da emergencia ate o inicio do florescimento. Os tratamentos com cloreto de mepiquat reduziram a altura da planta desde a emergencia, com interacoes entre os fatores analisados. O numero de botoes florais e de ramos, a area foliar, a materia seca da parte aerea e a altura da insercao do no cotiledonar tambem foram reduzidos pelos tratamentos.

Produção de laranja com plantas de cobertura permanente na entrelinha

The objective of this work was to evaluate water status, physiological parameters and fruit yield of the Pear orange on Rangpur lime rootstock, as well as soil water content in different orchard floor vegetation management. Field experiment was set up in 1993, at Alto Parana, northwest of the state of Parana, Brazil. The soil is a Typic Paleudults. Three treatments were evaluated: bahiagrass (Paspalum notatum), legume (Arachis pintoi), and spontaneous vegetation plus herbicide. The experimental design was in random blocks with three replicates. From 1999 to 2003, the following measurements were made: photosynthesis rates, stomatal conductance, leaf water potential, fruit yield and soil water content. Legume keeping in the interrows causes higher stress to orange plants. Bahiagrass assures better water and metabolic relations to Pear orange tree. Fruit yield orange is not influenced by orchard floor vegetation management.

Embebição de sementes e aplicação foliar com cloreto de mepiquat no crescimento e produção do algodoeiro

Foi avaliado o efeito do tratamento de sementes de algodao, cultivar IPR 120, embebidas em solucoes com cloreto de mepiquat e a interacao com a aplicacao foliar sequencial deste produto no crescimento, desenvolvimento e producao de algodao, em condicoes de campo, em Londrina, PR. O delineamento experimental foi o de blocos casualizados, em esquema fatorial 5 x 2, sendo um fator a embebicao das sementes com as concentracoes de cloreto de mepiquat [0; 0,5; 2,5; 5 e 7,5% (v/v)] e o outro a aplicacao foliar (aplicacao e nao), com quatro repeticoes. As duas primeiras aplicacoes foliares ocorreram aos 17 e 32 dias apos emergencia e as demais a cada 10 dias de intervalo, totalizando sete aplicacoes. A embebicao com regulador afetou a altura da planta, a altura da insercao do no cotiledonar, nao tendo atuacao sobre a altura da insercao do primeiro ramo produtivo, numero total de ramos, numero de ramos frutiferos, numero de macas por planta e no numero de macas na primeira posicao dos ramos frutiferos, variaveis estas afetadas com aplicacao foliar.

Photosynthesis of individual leaves in a coffee plant

The great variability in income irradiance over a plant canopy makes difficult the comparison of photosynthesis rates among leaves in a plant and their integration. In this study, photosynthetical rates of ten different leaves of a coffee plant were obtained during a day. The daily variation in photosynthetic rates showed a peak between 7:00 h and 9:00 h with higher values measured for the leaves positioned at the sunrise direction and northern orientation. Lower values were consistently observed for leaves at inner position of the plant. After 9:00 h, despite the increase in photosynthetically active radiation, photosynthetic rates decreased steadily to reach negligible values at sunset. The reductions on photosynthesis rates can also be attributed to increasing stomatal resistance. Since number of leaves is highly variable in coffee plants, those results make evident how difficult is to integrate and estimate whole plant photosynthesis by taking the average of 10 leaves.

Desenvolvimento do algodoeiro em resposta a modo de aplicação e doses de cloreto de mepiquat via sementes

A aplicacao do regulador de crescimento via embebicao de sementes apresenta alguns inconvenientes, dentre eles, a necessidade de secagem das sementes apos o tratamento. O objetivo do trabalho foi avaliar o efeito do tratamento de sementes com Cloreto de Mepiquat (CM), embebidas e aplicadas diretamente nas sementes de algodao, no crescimento das plantas. Os tratamentos foram arranjados em blocos casualizados, com seis repeticoes, utilizando a linhagem PR 02-307. O experimento foi constituido por cinco tratamentos: sementes sem tratamento; aplicacao direta sobre as sementes de CM a 3,75 e 7,5g i.a. kg-1 de sementes e embebidas em solucao de CM a 3,75 e 7,5g i.a. kg-1 de sementes. Apos os tratamentos, a semeadura foi feita em vasos com tres litros de solo em casa de vegetacao. Foram determinadas a altura e a area foliar do inicio ate 90 dias apos emergencia e a fitomassa da materia seca no final do experimento. Os tratamentos em que os reguladores de crescimento independentes da dose e forma de aplicacao foram utilizados na semente provocaram reducao na altura da planta desde a emergencia. O CM pode ser utilizado no tratamento de sementes, tanto por embebicao, quanto por aplicacao direta, com efeitos semelhantes na reducao da altura, da area foliar e da massa seca de folhas e de caules das plantas de algodoeiro, com efeito proporcional a dose utilizada.

Cotton zoning based on sowing periods of lower risk in Parana state, Brazil

Cotton is cultivated in the North and West of Parana State, southern Brazil, under conditions of climatic risk variable in space and time. Risks of temperature below 15oC at the establishment period, daily average temperature below 20oC at the stage of cotton boll opening, and soil water deficit for both plant establishment and flowering periods, were estimated to identify homogeneous zones with sowing periods of lower climatic risk. The time interval with adequate temperature, associated with minimum risks of the other factors and yield data from field experiments allowed the identification of seven distinct zones, with best sowing periods ranging from September 20 to November 20. Official credit to the farmers is conditioned by the Central Bank of Brazil upon following these recommendation of best sowing periods for each municipality.

Desenvolvimento de gemas florais, florada, fotossíntese e produtividade de cafeeiros em condições de sombreamento

The objective of this paper was to evaluate the influence of shading, during the period of floral development, on floral bud, flowering, photosynthesis and grain yield of coffee plants. Adult plants IAPAR 59, grown in Londrina, Parana State, Brazil, were shaded in different periods, with shading screens with 50% porosity, and compared to open-grown plants. The shading screens were placed in monthly intervals, from April to August, and were all removed in the beginning of October. Shading density and period did not influence the amount of nodes in each event of development on floral bud, period and intensity of flowering, photosynthesis and grain yield of the coffee plants, which indicates that the interception of until 50% incident radiation, during the period of floral development, does not affect the yield potential of this crop.