Rachel Benetti Queiroz-Voltan

CARACTERIZAÇÃO ANATÔMICA DE FOLHAS DE CAFEEIROS RESISTENTES E SUSCETÍVEIS AO BICHO-MINEIRO (1)

The leaf miner Leucoptera coffeella (Guerin-Meneville, 1842) (Lepidoptera: Lyonetiidae) is the major pest of coffee culture, being responsible for significant production losses as result of premature leaf fall, and consequent reduction of the photosynthetic area. The Coffee Breeding Program of the Agronomic Institute (IAC) has transferred through crossing genes that confer resistance to leaf miner from Coffea racemosa to the susceptible species C. arabica. The main objective of this study was to characterize leaf tissues, at histological level, from the parental species C. racemosa and C. arabica, and also from hybrids exhibiting different resistance levels. Histological analyses were performed in leaf transversal sections, and included measurements of cuticles and epidermis thickness, total palisade and spongy parenchyma, total leaf thickness, and percentage of the palisade parenchyma from total mesophyll. Results revealed that there were significant differences in leaf thickness between parental species C. arabica and C. racemosa. However, in hybrids no such difference could be observed between resistant and susceptible progenies, suggesting that the anatomical differences of parental genotypes are not related to resistance mechanisms to L. coffeella. When leaf lesions caused by insect attack were measured one and four days after larvae eclosion a slow insect development was observed in resistant plants, which could be related to a presence of specific chemicals in the palisade parenchyma.

CARACTERIZAÇÃO MORFOLÓGICA DE ACESSOS DE GERMOPLASMA DE QUATRO ESPÉCIES BRASILEIRAS DE AMENDOIM-SILVESTRE

Caracterizaram-se morfologicamente os acessos de germoplasma de especies silvestres brasileiras de amendoim do genero Arachis L., Sect. Arachis e analisaram-se a similaridade genetica entre acessos da mesma especie e entre as especies. Realizou-se o experimento nos anos agricolas de 1993 a 1996, no Nucleo Experimental de Campinas, do Instituto Agronomico (IAC). Avaliaram-se os acessos disponiveis no Banco Ativo de Germoplasma de Especies Silvestres de Arachis, da Embrapa Recursos Geneticos e Biotecnologia (CENARGEN - Brasilia, DF), das especies A. palustris Krapov., W.C. Gregory & Valls, A. decora Krapov., W.C. Gregory & Valls, A. praecox Krapov., W.C. Gregory & Valls e A. stenosperma Krapov. & W.C. Gregory, efetuando-se anotacoes fenotipicas quantitativas e qualitativas, conforme lista de descritores morfologicos. Observou-se que os acessos de A. stenosperma sao semelhantes, apesar da sua grande distância geografica, e diferem das demais especies, formando um grupo mais coeso. Caracteres como o diâmetro do eixo central e o comprimento dos frutos e das sementes serviram para distingui-la das demais especies. Arachis decora apresentou alta variacao entre acessos nos varios caracteres morfologicos estudados. A. palustris apresentou alta variacao morfologica entre acessos, ainda que tenham sido analisados apenas dois, para altura da planta, largura da semente, dimensoes do esporao, istmo, foliolo, raque e eixo central e quanto a presenca e ausencia de tricomas no foliolo. Arachis praecox, representada por um unico acesso, aproximou-se mais de A. decora que das demais especies.

EFEITO DA XYLELLA FASTIDIOSA EM CAFEEIROS EM DIFERENTES REGIÕES EDAFOCLIMÁTICAS (1)

A bacteria Xylella fastidiosa vem causando problemas para a cafeicultura, uma vez que sua presenca, associada a diversos fatores de estresse, provoca um decrescimo na producao devido a diminuicao no numero e tamanho dos frutos e a morte de alguns ramos. Este trabalho objetiva avaliar o efeito da X. fastidiosa sobre cultivares de Coffea arabica (enxertados ou nao) atraves da quantificacao da proporcao de vasos do xilema obstruidos pela bacteria, nas diferentes partes da planta e entre ramos com e sem sintoma da doenca, em experimentos desenvolvidos em diferentes regioes edafoclimaticas. Avaliou-se tambem a distribuicao das classes de infeccao nas diferentes partes da planta nos materiais geneticos estudados. Os experimentos foram instalados em 1986 em Mococa e Garca (SP) e as amostras para o estudo anatomico, retiradas em abril de 1998 e 2000 (periodo de estresse hidrico), respectivamente, das plantas de cafeeiros dessas areas. Na regiao de Mococa, observou-se que a nervura principal e o peciolo foram os tecidos com proporcao maior de vasos do xilema obstruidos pela X. fastidiosa; na regiao de Garca, foram o peciolo e o caule. Nao houve diferencas significativas na obstrucao de elementos de vaso do xilema do cafeeiro ocasionado pela bacteria entre as duas regioes estudadas. Nao houve tolerância a bacteria nos materiais geneticos, havendo no entanto variacao dentro de cada um deles. Na regiao de Garca, nas plantas de cafe, observou-se alta proporcao de vasos obstruidos nas raizes (3%), entretanto, nao houve dano maior na parte aerea.

Resposta de cultivares de arroz-de-sequeiro à calagem

A field experiment was laid out in a quartz sandy soil (Quartzipsamment) in Assis, State of Sao Paulo, Brazil, having cation exchange capacity of 35 mmolc.dm-3 and 9% base saturation. The differential response of the upland rice cultivars IAC 25, IAC 47, IAC 165 and Araguaia to the rates of 0, 2, 4 e 6 t.ha-1 of dolomitic and 2 t.ha-1 of calcitic limestone as additional treatment was evaluated. The limestone was applied in October of 1991 and the evaluations were carried out during the 1992-93 growth period. Twenty days after the plant emergence, the shoots were sampled for nutrient chemical analysis and twenty days later roots were sampled for anatomical studies. Two years after liming the largest base saturation was only 55%. The root structure remained unaltered with the liming treatments; some differences occurred only on the cortex central vascular ratio. The IAC 165 cultivar was the only one that did not respond to the limestone rates and that decreased the cortex/central vascular ratio. The liming decreased the plant manganese contents associated with the temporary soil flooding. There was also a decrease in phosphorus, potassium and zinc contents, but the nitrogen, calcium, magnesium, and iron contents increased. Shoot fresh matter yield was larger with dolomitic than with calcitic limestone for all cultivars, except IAC 47. All the cultivars showed higher magnesium and lower calcium contents in the shoots with dolomitic than with calcitic limestone. Although a positive yield response could not be obtained in the present study, it can be inferred that when upland rice is used in these soils for crop pasture renewals, dolomitic limestone might be recommended to correct acidity and magnesium deficiency in plant.

Variações na anatomia foliar de videira Niagara em diferentes sistemas de condução

Variations in leaf anatomy are caused by several environmental factors, mainly the availability of solar radiation, leading to possible changes in photosynthetic capacity and crop yield. This paper aims to identify alterations in grapevine ‘Niagara Rosada’ and ‘Niagara Branca’ leaf anatomy grown in three different training systems: double cordon (ESP), lyre (Y) and lyre with plastic (YPLA). The anatomical studies were made using mature leaves, external in relation to the canopy, collected in distinct regions of vine plants (lower, middle and upper). For anatomical characterization the samples were fixed in FAA, embedded in paraffin, sectioned in microtome and stained with safranin-alcian blue. Slides were examined with an optical microscope with the aid of the image analysis software Motic and the video image was acquired by using a JVC video camera attached to the same optical microscope. Leaf anatomy parameters were measured for ten leaves collected in each treatment: thickness of the leaf blade, of the palisade and of the spongy parenchyma, of the adaxial and abaxial epidermis and the ratio of palisade and spongy parenchyma. Analyses of variance were performed by F test and the means were compared by the Tukey test at 5% probability. The results indicate that the Niagara Branca and Niagara Rosada cultivars conducted in ESP had a greater average leaf blade thickness, but they were less productive when compared with Y and YPLA. Leaves grown under sunlight showed higher leaf thickness due to a greater development of palisade parenchyma, irrespective of the conduction system.

COMPARAÇÕES SAZONAIS DO EFEITO DA XYLELLA FASTIDIOSA EM CULTIVARES DE CAFEEIRO (1)

SEASONAL COMPARACTIONS OF XYLELLA FASTIDIOSA EFFECT IN COFFEE CULTIVARS Historically, coffee plants showing atrophy and scorch branch were attributed to nutritional disorders due to successive high yields. The bacteria XylelLa fastidiosa Wells et al. is currently the most reported pathogen related with the problem and the symptoms are associated with stress. Although the bacteria has been well studied in the United States particularly in grape, few is known about the pathogenhost-vector relationship. The present studies were carried out with coffee plants (grafted or not grafted) aiming to evaluate xylem vessels obstruction in various plant parts, including branches with and without

Alterações anatômicas em algodoeiro infectado pelo vírus da doença azul

ANATOMICAL ALTERATIONS IN BLUE DISEASE INFECTED COTTON PLANT Cotton blue disease is caused by a virus whose morphological and molecular characteristics is not well known and so demanding information its phytosanitary and epidemiological characteristics. Evidences of an aphid borne (Aphis gossypii Glover) circulative (persistent) type of transmission, associated with a recent molecular report, sustain for a virus species belonging to the Luteoviridae family. Aiming to understand virus-host pathogenesis as well as to contribute with diagnostic and breeding aspects of cotton blue disease, in the present work, structural studies were performed via anatomical comparative analysis of health and infected plant tissues. For the anatomical studies, leaves from infected cotton plants were chosen when showing typical symptoms, such as: stunting, reduced leaf area with chlorotic vein and edges curled downward; clustered leaves, flowers and fruits due to reduced stem internodes. The results revealed that infected tissues present an increase in callose accumulation and calcium oxalate crystals; integrity of chloroplasts, which were distributed on the peripheral mesophyll cells, revealed a chemical alteration in the interior of palisade parenchyma cells. Inclusions in phloem and occasionally also xylem vessels were observed. The callose accumulation and the presence of inclusions in the phloem vessels are indications of a preferential relationship of the virus to these tissues.

Variação de terpenos em Hyptis suaveolens e seu papel na defesa contra herbívoros

Acompanhou-se o desenvolvimento de populacoes de Hyptis suaveolens (L.) Poit. (Labiatae) em tres localidades paulistas: Horto Florestal de Sumare, Câmpus da UNICAMP (Campinas) e Fazenda Santa Genebra (Distrito de Barao Geraldo, Campinas), em 1981-83. Em cada local, escolheu-se uma populacao exposta a luz e outra, a sombra, com o objetivo de verificar em que fase do ciclo de vida as populacoes se tornavam mais suscetiveis ao ataque de herbivoros; de estimar a abundância dos herbivoros naturais e seus efeitos nas populacoes e a consequencia da variacao quimica dos monoterpenos que nelas ocorrem sobre os herbivoros. As populacoes tornavam-se mais suscetiveis aos herbivoros no periodo que antecedia a floracao. Nao se observou forte ataque de herbivoros nessa fase, embora se apresentassem em maior densidade. Os resultados sugerem que a variacao na composicao quimica possa afetar o desenvolvimento de herbivoros generalistas. No entanto, o Pyrausta insignatalis Guenee (Lep.-Pyralidae-Pyraustinae), provavelmente bem adaptado a planta, parece nao ter sido afetado por esses terpenos. Nao se detectaram diferencas entre populacoes expostas ao sol ou a sombra. Tais resultados apoiam a ideia de que a variabilidade quimica dentro de populacoes vegetais e importante estrategia de defesa contra herbivoros, dificultando-lhes a especializacao.

Caracterização da anatomia foliar de cafeeiros arábica em diferentes períodos sazonais

A seca e um dos fatores que limitam o desenvolvimento e a produtividade do cafeeiro. O objetivo deste estudo foi analisar a anatomia de folhas desenvolvidas nos periodos chuvoso e seco, em nove cafeeiros de Coffea arabica L., descritos anteriormente como tolerantes ou sensiveis a deficit hidrico, para identificar caracteres estruturais de tolerância a seca. Foram mensurados o tamanho e a densidade de estomatos e celulas epidermicas, a espessura das epidermes e do mesofilo, o diâmetro do peciolo e da nervura principal, a espessura do floema e xilema na nervura principal e no peciolo e o diâmetro e a frequencia de elementos de vasos do xilema. Diferencas observadas entre a estrutura foliar dos cafeeiros avaliados e as condicoes de desenvolvimento da folha (periodos chuvoso e seco) indicaram que ha uma plasticidade anatomica favoravel em relacao as condicoes de seca. Espessuras maiores do parenquima palicadico e do limbo total e raios maiores do floema e xilema no peciolo e na nervura principal foram considerados caracteristicas estruturais favoraveis para suportar a escassez de agua e estas poderiam ser utilizadas como criterios para selecionar cultivares tolerantes a seca. Foram considerados mais adaptados a seca os seguintes cafeeiros: Geisha, Semperflorens, BA10, IAC H 8105-7, IAC H 8421-2 e a cultivar Catuai Vermelho IAC 81.