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Knowledge about the seasonality of different genotypes of Coffea canephora is an important tool for this crop management, particularly with regard to irrigation and fertilisation issues. This study was conducted in Espírito Santo, Brazil and aimed at to evaluate the seasonal vegetative growth in genotypes of C. canephora, as related to climatic factors, based on the growth of groups of orthotropic and plagiotropic branches with different ages. Three groups of plagiotropic branches and one group of orthotropic branches of 14 genotypes (Ipiranga and 13 that belonged to the variety Vitória) were selected and marked to followed along the one-year experiment. Three-year-old plants were cultivated under full-sun conditions, with a spacing of 3 m between rows and 1 m between plants. The growth rates of the orthotropic and plagiotropic branches differed among the genotypes and underwent seasonal variation during the entire year, with high correlations to the air temperature. Under the natural experimental conditions, the growth rate of the branches decreased when the minimum air temperatures were below 17.2ºC for most of the genotypes studied. The plagiotropic branches presented lower vegetative growth, mainly for the coffee berries, compared to the younger branches. Presumably, the genotypes of C. canephora demanded more nutrients for growth between mid-September and the second week of May.

RESUMOForam estudados o crescimento, a partição de assimilados e a produção de grãos nas cultivares de arroz BRS Pelota (maior produtividade) e BRS Firmeza (menor produtividade). O experimento foi realizado em casa de vegetação, com plantas cultivadas em vaso. Utilizou-se o delineamento experimental inteiramente casualizado, com duas cultivares, nove coletas e quatro repetições por tratamento. Com a cultivar BRS Pelota houve maior acúmulo de matéria seca total (W t ), principalmente no fim do ciclo, bem como maior área foliar (A f ). A matéria seca alocada para o colmo + bainha e às panículas também foi maior em BRS Pelota. Porém, a porcentagem de W t destinada às panículas aos 125 DAE foi semelhante entre as cultivares. Em BRS Firmeza, o aumento em W t nas raízes pode ter influenciado o direcionamento de fotoassimilados para os grãos e contribuído para o atraso na senescência das plantas. A produtividade de BRS Pelota foi maior que a de BRS Firmeza (17,4 contra 11,8 g por vaso) e seu número de panículas por planta por vaso foi três vezes superior em relação à cultivar BRS Firmeza. O componente de produção de maior expressão no rendimento foi o número de panículas. A maior produtividade da cultivar BRS Pelota pode estar relacionada à maior área foliar e sua duração, o que permite o fornecimento de elevada quantidade de fotoassimilados por um período maior.Palavras-chave: matéria seca, análise de crescimento, área foliar, BRS Firmeza, BRS Pelota. ABSTRACT GROWTH AND ASSIMILATES PARTITIONING IN RICE CULTIVARS DIFERING IN GRAIN YIELD POTENTIALThe growth, assimilate partitioning and grain yield in BRS Pelota (high yield) and BRS Firmeza (low yield) rice cultivars were evaluated. The experiment was conducted in greenhouse (Department of Botany, Federal University of Pelotas) with complete randomized design composed by two cultivars, nine plant sampling times and four replicates. BRS Pelota rice cultivar exhibited higher accumulation of total dry matter (W t ), mainly at the end of life cicle, as well as higher leaf area (A f ). The dry matter allocated toward culm + sheath and panicles was higher in BRS Pelota. However, the W t percentage accumulated in panicles at 125 DAE was the same between cultivars. In BRS Firmeza the increase in W t in the roots may had influenced photoassimilates partitioning toward grains, and also contributed to delay of in plant senescence. Grain yield was higher in BRS Pelota than in BRS Firmeza (17.4 versus 11.8 g vaso), and also panicle number was three times greater in relation to BRS Firmeza. The yield component which exhibited higher relevance for productivity was the panicle number. The higher grain yield of BRS Pelota could be related to higher leaf area and leaf area duration, which allows the provision of elevated quantity of photoassimilates during longer period time.

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The portable chlorophyll (Chl) meter (CL-01, Hansatech) has been successfully used for a rapid and direct estimation of total Chl content in the leaves of some crops. We compared CL-01 meter readings (Chl value) and Chl contents in leaves of Zea mays, Cucumis sativus, Raphanus sativus, and Ceiba speciosa. Chl index was linearly and positively correlated to Chl content in all the species.Additional key words: Ceiba; Cucumis; Raphanus; Zea.---Plants contain chlorophylls (Chls) a and b. The two compounds have different solubilities in organic solvents, and somewhat different, though overlapping, electronic spectra in the visible region. Traditionally, chemical methods of determination have required Chl extraction by a solvent, followed by the spectrophotometric determination of absorbance by the Chl solution, and conversion from absorbance to concentration using standard equations (Arnon 1949, Lichtenthaler 1987, Ritchie 2008. In the standard method of Chl determination, extraction requires destructive sampling and is relatively time consuming (Richardson et al. 2002). More recently, non-destructive optical methods, based on the absorbance and/or reflectance of radiation by the intact leaf have been developed. Optical methods yield a 'Chl index' value that expresses relative Chl content but not absolute Chl content per unit leaf area or per mass of leaf tissue. These newer methods are non-destructive, very quick, and can be used in the field (Markwell et al. 1995, Hawkins et al. 2007.Many papers show the application of "Chl value" to the estimation of leaf Chl content (Richardson et al. 2002, Uddling et al. 2007), but some have failed to show the applicability of the index across different studies, plant species, or stresses. Neufeld et al. (2006) working with ozone-affected leaves of cutleaf coneflower (Rudbeckia laciniata var. digitata) observed that when relatively uninjured leaves were measured, SPAD meter readings were linearly related to total Chl content. However, when leaves with foliar injury were added, it was no longer possible to use the same equation to obtain Chl estimations for both classes of leaves.The objective of this work was to evaluate the existence of relation between the Chl content and "Chl value" measured by hand-held Chl meter CL-01 in maize (Zea mays), cucumber (Cucumis sativus), radish (Raphanus sativus), and floss-silk tree (Ceiba speciosa). Plants were grown from seed in a glasshouse. Approximately 50 leaf samples of the each species, spanning as wide a range of Chl contents as possible, from very pale yellow to very dark green leaves, were used. One hand-held Chl meter, the CL-01 (Hansatech, King's Lynn, Norfolk, England) was used. This equipment provides a convenient, low cost method of measuring the relative Chl content of a leaf sample using dual wavelength optical absorbance (620 and 940 nm) measurements from leaf samples. Five separate measurements were made on each leaf and we used the arithmetic mean of these measurements for all subsequent analyses, and the results were expres...

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-The objective of this work was to evaluate the physiological changes that occur in different leaves during the early and late grain-fi lling stages of two rice genotypes (Oryza sativa subsp. indica, BRS Pelota cultivar, and O. sativa subsp. japonica, BRS Firmeza cultivar), which present differences in grain yield potential. The plants were cultivated in greenhouse. Pigment content, chlorophyll fl uorescence, electron transport and oxygen evolution rate were determined in the grain-fi lling stage, from the fi rst to the forth leaf (top to bottom). Pigment content, photochemical effi ciency of photosystem II and electron transport decreased signifi cantly according to the position of leaves in 'BRS Pelota'. The BRS Firmeza cultivar shows higher pigment content and higher activity of the photosynthetic apparatus in comparison to 'BRS Pelota' during the grain-fi lling stage.Index terms: Oryza sativa, oxygen evolution rate, photochemical quenching, photosystem II, photochemicol effi ciency, stay green. Análise fi siológica da senescência foliar de duas cultivares de arroz com diferentes potenciais de produtividadeResumo -O objetivo deste trabalho foi avaliar as mudanças fi siológicas que ocorrem em diferentes folhas durante o início e o fi nal do estádio de enchimento de grãos em dois genótipos de arroz (Oryza sativa subsp. indica cultivar BRS Pelota e O. sativa subsp. japonica cultivar BRS Firmeza) que apresentam diferenças no potencial de produção de grãos. As plantas foram cultivadas em casa de vegetação. Os teores de pigmentos, a fl uorescência da clorofi la e a taxa de liberação de oxigênio foram determinados no estádio de enchimento de grão da primeira à quarta folha (do topo à base). O teor de pigmentos, a efi ciência fotoquímica do fotossistema II e o transporte de elétrons decresceram signifi cativamente de acordo com a posição das folhas na cultivar BRS Pelota. A cultivar BRS Firmeza apresentou maior teor de pigmentos e maior atividade do aparato fotossintético em comparação à 'BRS Pelota' durante o estádio de enchimento de grão.Termos para indexação: Oryza sativa, taxa de evolução de oxigênio, extinção fotoquímica, fotossistema II, efi ciência fotoquímica, senescência retardada.