RESUMO A produção de café entre a primeira e segunda colheita apresenta diferença na carga dos frutos com a idade da planta, podendo ter efeito na troca gasosa. Objetivou-se avaliar o efeito do aumento na carga de frutos que acontece entre a primeira e a segunda colheita do ciclo produtivo do Coffea arabica L. na avaliação da troca gasosa, no decorrer dos dois estados fenológicos do fruto. Foram utilizados os acessos E057, E318, E338 e E554, bem como delineamento inteiramente casualizado, com três repetições, tendo-se os acessos como tratamentos e as medições de colheita do ciclo produtivo como medidas repetidas. As variáveis produtividade por planta, número de frutos, taxas de crescimento absoluto de altura e tronco, área foliar, relação folha-fruto e trocas gasosas da folha foram medidas nas fases fenológicas de enchimento e maturação dos frutos. O aumento da carga de frutos que ocorre com a idade na segunda colheita, em relação à primeira, apresentou efeito positivo e significativo na taxa de assimilação líquida, o qual não era esperado para as relações folha-fruto obtidas. Da mesma forma, as diferenças nas taxas de assimilação foram maiores durante a fase de enchimento dos frutos. Isso sugere que a relação fonte-dreno pode variar com a idade de cultivo e estádio fenológico do fruto, e não depende totalmente da relação folha-fruto.

ABSTRACT Coffee production between the first and second harvest presents a difference in the fruit load with the plant age that could affect the leaf gas exchange. This research aimed to evaluate the effect of the increase in fruit load that occurs between the first and second harvest of the Coffea arabica L. production cycle on the measured gas exchange, at the two phenological stages of the fruit. The accessions E057, E318, E338 and E554 were used, as well as a completely randomized design, with three replications, using the accessions as treatments and the harvest measurements during the production cycle as the repeated measures. The variables yield per tree, number of fruits, absolute growth rates for height and stem, leaf area, leaf-to-fruit ratio and leaf gas exchange were measured across the phenological stages of fruit filling and ripening. The increase in the fruit load that occurs with age in the second harvest, if compared to the first harvest, showed a positive and significant effect on the net assimilation rate that was not expected for the obtained leaf-to-fruit ratios. Likewise, the differences in the assimilation rates were higher during the fruit-filling stage. This result suggests that the source-sink relationship may vary with the crop age and fruit phenological stage, and is not entirely depend on the leaf-to-fruit ratio.

RESUMO O amadurecimento da cana-de-açúcar é condicionado pela interação entre os fatores biológicos da cultura e o clima. Objetivou-se avaliar os efeitos de algumas variáveis meteorológicas sobre o teor de sacarose, durante o período de maturação, no vale do rio Cauca (Colômbia). As avaliações foram realizadas em sete localidades, durante quatro períodos, cada um com duração de três meses. As variáveis meteorológicas de temperatura máxima, média e mínima do ar, déficit de pressão de vapor diurno e precipitação foram avaliadas em relação à variável sacarose (% cana). Os resultados mostraram que uma baixa precipitação e um alto déficit de pressão de vapor aumentaram o teor de sacarose nos colmos. Altas temperaturas mínimas durante a maturação diminuíram os níveis de sacarose, embora seu efeito fosse menos perceptível do que o mencionado anteriormente. As condições meteorológicas nas diferentes localidades causaram diferenças substanciais na concentração de sacarose dos colmos, principalmente durante o início da fase de maturação. No entanto, essas diferenças foram reduzidas pela idade da colheita e pelos períodos de ocorrência de chuvas ou secas.

ABSTRACT Sugarcane ripening is conditioned by the interaction between biological factors of the crop and climate. This study aimed to evaluate the effects of some meteorological variables on the sucrose content, during the ripening period, in the Cauca river valley (Colombia). The evaluations were conducted at seven locations, during four periods, being each one a three-month period. The meteorological variables of maximum, mean and minimum air temperature, diurnal vapor pressure deficit and precipitation were evaluated with respect to the sucrose variable (% cane). The results showed that a low precipitation and a high vapor pressure deficit increased the sucrose content in the stems. High minimum temperatures during the maturation stage decreased the sucrose levels, although their effect was less noticeable than previously mentioned. The meteorological conditions in the different localities caused substantial differences in the sucrose concentration of the stems, especially during the beginning of the maturation phase. However, these differences were reduced by the age of the crop and by the periods of rainfall or drought occurrence.

Resumen El objetivo de este estudio consistió en conocer el comportamiento de Hevea brasiliensis en lo que se refiere al desempeño fotosintético, en las regiones caucheras del nordeste y el Bajo Cauca (Antioquia, Colombia), como base para futuros estudios de desempeño clonal entre ambientes. El intercambio de gases se cuantificó mediante un analizador infrarrojo de gases portátil, y en las variables fotosintéticas para los siete clones se calculó un valor medio, a partir del cual se estimó el área bajo la curva. El máximo valor de fotosíntesis se alcanzó a las 8:00 en San Roque (10,97 μmol [CO2] m-2s-1), y 9:00 en Caucasia (7,84 μmol [CO2] m-2s-1). La transpiración máxima fue de 3,55 mmol [H2O] m-2s-1 en San Roque, y de 5,16 mmol [H2O] m-2s-1 en Caucasia, mientras que la conductancia estomática máxima fue de 0,18 mol [CO2] m-2s-1 y de 0,16 mol [CO2] m-2s-1, respectivamente. Las plantas de caucho en Caucasia presentaron una mayor tasa de asimilación neta acumulada (271.934 μmol [CO2] m-2día-1), superando los 226.287 μmol [CO2] m-2día-1 de San Roque, lo que representa una diferencia de 45.647,52 μmol [CO2] m-2día-1. La mayor acumulación de carbono con menor inversión de energía lumínica (697.638 μmol [CO2] μmol [fotón]-1día-1) se obtuvo en San Roque. Por lo tanto, en lo que respecta al intercambio gaseoso y al uso de la energía lumínica, Hevea brasiliensis presentó una mayor adaptación ambiental en San Roque.

Abstract The aim of this study was to determine the behavior of the rubber plant Hevea brasiliensis regarding its photosynthetic performance in the rubber producer regions in Nordeste and Bajo Cauca, in the department of Antioquia, Colombia, as a baseline for future clonal performance studies among environments. Gas exchange was recorded using a portable infrared gas analyzer, and for the photosynthetic parameters for seven genotypes (clones) a medium value was calculated and was later used to estimate the area under the curve. The maximum photosynthetic value was reached at 8:00 hours in San Roque (10.97 μmol [CO2] m-2s-1) and at 9:00 hours in Caucasia (7.84 μmol [CO2] m-2s-1). Maximum transpiration was 3.55 mmol [H2O] m-2s-1 in San Roque and 5.16 mmol [H2O] m-2s-1 in Caucasia, while the maximum stomatal conductance was 0.18 mol [CO2] m-2s-1 and 0.16 mol [CO2] m-2s-1 in San Roque and Caucasia, respectively. The rubber plants in Caucasia had a higher accumulated net assimilation rate (271,934 μmol [CO2] m-2day-1) than what was found in San Roque (226,287 μmol [CO2] m-2day-1), showing a difference of 45.647,52 μmol [CO2] m-2day-1. The highest carbon accumulation with the lowest light energy investment (697,638 μmol [CO2] μmol [photon]-1day1) was found in San Roque. Therefore, regarding gas exchange and the use of light energy Hevea brasiliensis showed greater environmental adaptation in San Roque.

Resumo O objetivo deste estudo consistiu em conhecer o comportamento de Hevea brasiliensis no que se refere ao desempenho fotossintético, nas regiões borracheiras do nordeste e do Baixo Cauca (Antioquia, Colômbia), como base para futuros estudos de desempenho clonal entre ambientes. O intercâmbio de gases foi quantificado mediante um analisador infravermelho de gases portátil, e nas variáveis fotossintéticas para os sete clones foi calculado um valor médio, a partir do qual foi estimada a área sob a curva. O máximo valor de fotossíntese foi alcançado às 8:00 em San Roque (10,97 μmol [CO2] m-2s-1), e 9:00 em Caucasia (7,84 μmol [CO2] m-2s-1). A transpiração máxima foi de 3,55 mmol [H2O] m-2s-1 em San Roque, e de 5,16 mmol [H2O] m-2s-1 em Caucasia, enquanto a condutância estomática máxima foi de 0,18 mol [CO2] m-2s-1 e de 0,16 mol [CO2] m-2s-1, respectivamente. As plantas de borracha em Caucasia apresentaram maior taxa de assimilação líquida acumulada (271.934 μmol [CO2] m-2dia-1), superando os 226.287 μmol [CO2] m-2dia-1 de San Roque, o que representa uma diferença de 45.647,52 μmol [CO2] m-2dia-1. A maior acumulação de carbono com menor investimento de energia lumínica (697.638 μmol [CO2] μmol [fóton]-1dia-1) obteve-se em San Roque. Portanto, no que se refere ao intercâmbio gasoso e ao uso da energia lumínica, H. brasiliensis apresentou maior adaptação ambiental em San Roque.

La estructura del dosel tiene un marcado efecto sobre la interceptación de la radiación y la fotosíntesis de la planta, además de otros procesos. El estudio se llevó a cabo en la Estación Central Naranjal de CENICAFÉ (Centro Nacional de Investigaciones de Café - Chinchiná, Caldas, Colombia) sobre 25 genotipos de Coffea arabica L., divididos en dos grupos. El primer grupo, con plantas de porte alto (3.6 años) y el segundo con plantas de porte bajo (2.6 años), ambos sembrados a una densidad de 5000 plantas.ha-1. La distribución de los ángulos de las hojas y las ramas en el dosel se caracterizaron en los diferentes genotipos evaluados, así mismo los coeficientes de extinción teóricos de la radiación solar directa y difusa fueron estimados. En los genotipos de porte alto predominaron las distribuciones foliares plagiófila y esférica, mientras que en los de porte bajo fue la planófila. El parámetro x representa a la distribución elipsoidal de los ángulos foliares, este valor varió entre 0.09 y 2.21 para los genotipos de porte alto (verticales y esféricos) y entre 1.90 y 3.98 para los de porte bajo (horizontales). Los coeficientes de extinción teóricos para la radiación directa derivados del parámetro x variaron entre 0.63 a 0.83 para el grupo de porte alto, mientras que en el porte bajo mostraron valores entre 0.84 a 0.93. Para la radiación difusa, los coeficientes presentaron la misma tendencia, pero con valores menores. En cuanto al ángulo de inclinación de las ramas, se caracterizó por ser predominantemente planófilo.

The canopy structure has a marked effect on the interception of the solar radiation and the plant photosynthesis, in addition to other processes that in their group, are the result of the plant-environment interaction. The present research was carried out at the Central Station Naranjal of CENICAFÉ (National Coffee Research Center - Chinchiná, Caldas, Colombia) in 25 genotypes of Coffea arabica L. which were divided in two groups. The first one with tall aspect plants (3.6 years old) and the second one, with short plant aspect (2.6 years old) both planted in a density of 5000 plants.ha-1. The leaf and branches angles distribution in the canopy were characterized in the different assessed genotypes, also the theoretical extinction coefficients for direct and diffuse solar radiation were estimated. In genotypes of high aspect, the plagiophile and spherical leaf distribution predominated, as in the ones of short aspect the planophile did. The parameter x, represents the ellipsoidal distribution of the leaf angles, which varied between 0.09 and 2.21 for genotypes of high aspect (vertical and spherical) and between 1.90 and 3.98 for the ones of short aspect (horizontal). The theoretical coefficients of extinction for the direct radiation derived of the parameter x varied between 0.63 to 0.83 for the group of high aspect, and the short one, showed values between 0.84 to 0.93, for the diffuse radiation the coefficients showed the same trend but with minor values. As regards the inclination angles of the branches was characterized for being planophile predominant.

Allometric models based on measurements of single leaf dimensions or a combination there are useful tools for determining individual leaf area (LA) because they are non-destructive, precise, simple and economical methods. The present study was carried out at the Central Station Naranjal of Cenicafé, located in the Department of Caldas (Colombia), four models were defined using the variables length (L) and/or width (W) to estimate LA in coffee leaves of the Castillo® variety (Coffea arabica L.). Estimation of regression coefficients was performed using information recorded from 6,441 leaves (group 1), and their validation was performed using records from another 992 leaves (group 2). Leaves were collected from all strata of the canopy and ranged from 0.76 to 140 cm2 in LA. In addition to exhibiting coefficients of variation differing from zero based on t-tests at 1%, the evaluated models possess coefficients of determination between 0.93 and 0.99. Four expressions have developed and adjusted to estimate leaf area in individual leaves, based on the measurement of simple variables and non-destructive.

La investigación se desarrolló en la Estación Experimental San Antonio (EESA) de Cenicaña ubicada en el corregimiento de San Antonio de los Caballeros (Florida, Valle del Cauca). Se realizaron dos experimentos denominados condición húmeda (con lisímetros para el manejo artificial del nivel freático) y condición semiseca (en campo), utilizando un diseño de bloques completos al azar con tres repeticiones. Se evaluó el aerénquima presente en las raíces fibrosas de 13 variedades de caña de azúcar (Saccharum spp.) a 4, 6 y 8 meses después de la siembra y las variables agronómicas altura de planta, diámetro de tallo, población de tallos, peso de tallos por parcela y producción de sacarosa por parcela al momento de la cosecha. Se encontró una respuesta diferencial entre condiciones a causa de la falta de oxígeno (hipoxia). En condiciones húmedas el aerénquima ocupó 55% del área total de los tejidos en la raíz, sin diferencias estadísticas entre variedades; mientras que en condiciones semisecas sólo ocupó 33%. En ambas condiciones, el aerénquima no mostró asociación con las variables agronómicas evaluadas, no obstante la variedad CC01-1884 presentó el mejor comportamiento agronómico.

The research was developed at the experiment station San Antonio (EESA) of Cenicaña located in the village of San Antonio de los Caballeros (Florida, Cauca Valley). Two experiments were conducted one on semi-dry conditions and another on wet conditions, each one with a design of a randomized complete block with three replications. The aerenchyma observed in the fibrous roots of 13 varieties of sugarcane was evaluated (Saccharum spp) by 4, 6 and 8 months after planting. Agronomic variables as height, diameter, population, stalk weight of total plot, sucrose (% cane) and yield of sucrose per plot were evaluated at harvesting time. It was found that there was a differential response between environments because of the lack of oxygen (hypoxia) in soil. On wet conditions, the aerenchyma occupied 55% of the total area in the root tissues although did not show statistical differences between varieties, whereas the opposite occurred on semi-dry conditions where only occupied 33%. The aerenchyma was not associated with any agronomic traits evaluated. The variety CC 01-1884 had the best agronomic performance in the evaluations.