Ana Maria de Arruda Ribeiro

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.

Sombreamento de cafeeiros durante o desenvolvimento das gemas florais e seus efeitos sobre a frutificação e produção

The objective of this paper was to evaluate the influence of shading during the period of floral buds development on the growth and maturation of coffee fruits, production and grain size of Coffea arabica L. The experiment was carried out in Londrina, PR, Brazil. Plots of adult coffee plants were shaded monthly in April, May, June, July and August of 2004 using shading screens with 50% of porosity. The coverings were removed simultaneously at the beginning of October of the same year. The interception of 50% of incident radiation over the coffee canopy in different periods of floral buds development did not alter fruit growth and development. Fruit maturation was anticipated due to high temperatures and water deficit, however without significant differences on maturation periods among treatments. Grain yield and size were not affected by shading in the different periods.

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.