This study had three objectives: i) to observe maize inbred lines response to nitrogen (N) and ph... more This study had three objectives: i) to observe maize inbred lines response to nitrogen (N) and phosphorus (P) acquisition as well as their utilization efficiencies and traits of root morphology in contrasting levels of these nutrients, ii) to study the relationship between root morphology and nutrient use efficiencies for both nutrients, and iii) to identify contrasting parents with components N and P use efficiency for an inheritance study. We evaluated 15 inbred lines in two experiments conducted in contrasting conditions of N and P. We evaluated the shoot, root traits and nutritional efficiencies and observed the genetic variability for most traits. Selection can be practiced for most of these traits in specific environments. Under conditions of nutritional stress, average and heritability estimates were of lesser magnitude. In this study, the shoot and root morphology traits were shown to be associated with the acquisition efficiency of both N and P in all of the environments that were evaluated.
The effects of varying intensities of light on plants depend on when they occur, even if the tota... more The effects of varying intensities of light on plants depend on when they occur, even if the total amount of light received is kept constant. We designed an experiment using two clones of robusta coffee (Coffea canephora) intercropped with shelter trees in such a way that allowed us to compare coffee bushes shaded in the morning (SM) with those shaded in the afternoon (SA), and then confronting both with bushes receiving full sunlight over the course of the day (FS). The SM bushes displayed better gas-exchange performance than their SA and FS counterparts, in which the capacity for CO2 fixation was mainly constrained by stomatal (SA bushes) and biochemical (FS bushes) factors. Physiological traits associated with light capture were more responsive to temporal fluctuations of light rather than to the amount of light received, although this behavior could be a clone-specific response. The activity of key antioxidant enzymes differed minimally when comparing the SM and SA clones, but was much larger in FS clones. No signs of photoinhibition or cell damage were found regardless of the light treatments. Acclimations to varying light supplies had no apparent additional cost for constructing and maintaining the leaves regardless of the light supply. Both the SM and SA individuals displayed higher return in terms of revenue streams (e.g. higher mass-based light-saturated photosynthetic rates, photosynthetic nitrogen use efficiencies and long-term water use efficiencies) than their FS counterparts. In conclusion, shading may improve the physiological performance of coffee bushes growing in harsh, tropical environments.
Resende, R. S., Rodrigues, F. Á., Cavatte, P. C., Martins, S. C. V., Moreira, W. R., Chaves, A. R... more Resende, R. S., Rodrigues, F. Á., Cavatte, P. C., Martins, S. C. V., Moreira, W. R., Chaves, A. R. M., and DaMatta, F. M. 2012. Leaf gas exchange and oxidative stress in sorghum plants supplied with silicon and infected by Colletotrichum sublineolum. Phytopathology 102:892-898.
Crop Breeding and Applied Biotechnology (Online), 2011
This study aimed to verify the relationship between breeding for tolerance to low levels of soil ... more This study aimed to verify the relationship between breeding for tolerance to low levels of soil nutrients and for nutrient use efficiency in tropical maize. Fifteen inbred lines were evaluated in two greenhouse experiments under contrasting levels of N and P. The relationship between nutritional efficiency and tolerance to nutritional stress was estimated by the Spearman ranking correlation between the genotypes for the traits related to N and P use efficiency and phenotypic plasticity indices. The lack of relationship between the traits, in magnitude as well as significance, indicates that these characters are controlled by different gene groups. Consequently, simultaneous selection for both nutrient use efficiency and tolerance to nutritional stress is possible, if the mechanisms that confer efficiency and tolerance are not competitive.
Key message This study highlights that wood density integrates the xylem structural changes and p... more Key message This study highlights that wood density integrates the xylem structural changes and plays a key role in drought tolerance at the intraspecific level in clones of robusta coffee. Abstract Robusta coffee (Coffea canephora) is largely cropped in regions where drought stress is the major bottleneck limiting crop yields. We hypothesized that clonal differences in wood density (D w ) would be reflected in xylem anatomical differences with associated consequences for hydraulic functioning and ultimately drought tolerance. We assessed the major functional properties of water conduction systems at both the leaf and stem levels in 8-year-old clones of robusta coffee with varying degrees of drought tolerance. The plants were grown outdoors in 24-L pots and either irrigated or subjected to a 4-month water deficit. Upon drought imposition, increased D w , primarily associated with a rearrangement of the fiber matrix and secondarily associated with narrower vessels (although more numerous per cross-sectional area), was correlated with tolerance to hydraulic dysfunctions. Some coordination at the leaf level concerning hydraulic and stomatal anatomical patterns, with stem structural properties, was observed under ample irrigation, but this coordination was decoupled by the imposed drought stress. In conclusion, our data suggest a role for D w in drought tolerance in coffee; however, drought tolerance implies that clones that successfully thrive under low water supply might have compromised fitness under ample irrigation, suggesting a trade-off between D w and the conduction capacity in coffee.
Resumo -A presença de sais interfere no potencial hídrico do solo, reduzindo o gradiente potencia... more Resumo -A presença de sais interfere no potencial hídrico do solo, reduzindo o gradiente potencial entre o solo e a superfície da semente, restringindo a absorção de água pela superfície da semente, podendo influenciar significativamente no processo germinativo.O presente trabalho teve como objetivo avaliar o estresse salino sobre a germinação e o vigor de sementes de tomate (Lycopersicon esculentum M.). Os potencias osmóticos das soluções utilizadas foram 0,0 (controle); -0,4; -0,8; -1,2; -1,6 MPa, obtidos com NaCl como soluto, aplicado no substrato rolo de papel germitest, equivalente a 2,5 vezes o peso do papel, sendo os rolos mantidos nas temperaturas de 20, 20-30 e 30ºC, formando um esquema fatorial 5 X 3 (concentrações salinas X temperaturas). O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições. A avaliação do experimento foi feita através da porcentagem e do índice de velocidade de germinação, matéria fresca e seca da parte aérea e do si...
This study aimed to evaluate under photoautotrophic conditions the effect of CO2-enriched atmosph... more This study aimed to evaluate under photoautotrophic conditions the effect of CO2-enriched atmosphere (360 or 1,000 μmol CO2 mol−1 air) combined with two substrate types (agar or Florialite®) in vitro on plants of Pfaffia glomerata, an endangered medicinal species with promising applications in phytotherapy and phytomedicine. The effects of the treatments on the growth, stomatal density, Rubisco activity, carbon isotopic discrimination, metabolite accumulation, photosynthetic pigments and ultrastructural characteristics were investigated. After a 35-day cultivation period, the in vitro-growth of P. glomerata nodal segments under the different treatments resulted in plants with substantial differences in relation to their growth, photosynthetic pigments, stomatal density and leaf ultrastructural characteristics. The enrichment with CO2 coupled with a porous substrate increased the growth of P. glomerata. The stomatal density in the abaxial epidermis more than doubled in response to th...
Acclimations to low and high light levels are located in opposite extremes. We examined how the c... more Acclimations to low and high light levels are located in opposite extremes. We examined how the coffee plant (Coffea arabica), which is considered to be shade-demanding although it performs well under full sun exposure, can acclimate to a range of light regimens. We hypothesised that the growth and physiological performance depends on the total amount of light received by the plant per day and on the temporal order of diurnal variations in the light supply. The biomass accumulation and allocation and the key photosynthetic traits of pot-grown coffee seedlings were examined over a range of light treatments as follows: plants grown entirely under 100%, 40% or 10% sunlight; plants grown at either 40% or 10% sunlight from sunrise to midday and then submitted to full sunlight until sunset; and plants grown under full sunlight from sunrise to midday and then submitted to either 40% or 10% sunlight throughout the afternoon. The total biomass increased linearly with the increasing total lig...
Dentre as condições ideais para germinação, o tipo de solo é muito importante, pois, interfere nã... more Dentre as condições ideais para germinação, o tipo de solo é muito importante, pois, interfere não apenas na germinação das sementes mas, também, no desenvolvimento pós-seminal. Além da adubação, outro fator importante na emergência e crescimento das mudas é a luminosidade devido sua influência em processos como a fotossíntese. Neste trabalho, objetivou-se avaliar a influência da adubação com esterco bovino, torta de filtro e vinhaça, bem como da luminosidade na germinação e vigor de sementes de cenoura, em solo de mineração de calcário. O experimento foi conduzido em casa de vegetação, em 2005, em Alegre-ES. Utilizou-se o delineamento inteiramente casualizado, em arranjo fatorial 13 x 3 (adubações x luminosidades) e 4 repetições. Os tratamentos constaram de solo de mineração de calcário enriquecido ou não com adubação e 3 níveis de luminosidade. A adubação teve influência direta nas plântulas, pois, as menores intensidades (13.8 mol fótons m -2 s -1 ) aumentaram a germinação e altura destas, enquanto as maiores intensidades (1192.8 mol fótons m -2 s -1 ) aumentaram a velocidade de germinação e o acúmulo de matéria seca. A adubação com os 3 materiais orgânicos e NPK proporcionou maior altura e matéria seca às plantas.
... Heder Braun1; José Carlos Lopes2*; Leandro Torres de Souza3; Edilson Romais Schmildt4; Rithie... more ... Heder Braun1; José Carlos Lopes2*; Leandro Torres de Souza3; Edilson Romais Schmildt4; Rithiely Paschoa Queiroz Cavatte5; Paulo Cezar Cavatte6 ... A avaliação foi feita pela porcentagem de germinação, massa fresca e seca de plântulas, aos 65 dias após a semeadura. ...
... Heder Braun 1 ; Paulo Cezar Cavatte 2 ; José Augusto Teixeira do Amaral 3 ; José Francisco Te... more ... Heder Braun 1 ; Paulo Cezar Cavatte 2 ; José Augusto Teixeira do Amaral 3 ; José Francisco Teixeira do Amaral 3 ; Edvaldo Fialho dos ... Aos 18 dias após o plantio das estacas foi analisada a porcentagem de enraizamento (ENR), determinada através da proporção de estacas ...
Plants are often exposed to several adverse environmental conditions that potentially generate st... more Plants are often exposed to several adverse environmental conditions that potentially generate stress and thus negatively affect their growth and productivity. Understanding the physiological responses of crops to stress conditions is essential to minimizing the deleterious impacts of stress and maximizing productivity. Therefore, there is urgent need for more scientific research to increase our understanding of the physiological behavior of crops in response not only to a specific type of stress but also to multiple interacting stressors, such as water, and thermal stresses. The proper assessment of this information may result in important tools for monitoring the most promising genetic material in plant breeding programs. In this chapter, the plant strategies associated with satisfactory growth and yield under abiotic stress conditions are discussed, with emphasis in tropical environments. In addition, the state of the art on the physiology of the major abiotic stresses (drought, salinity, heat, nitrogen and phosphorus deficiencies and aluminum toxicity) and possible strategies to develop cultivars with
RITHIELY PASCHOA QUEIROZ CAVATTE 2 , LUIZ CARLOS CHAMHUM SALOMÃO 3 , DALMO LOPES DE SIQUEIRA 3 , ... more RITHIELY PASCHOA QUEIROZ CAVATTE 2 , LUIZ CARLOS CHAMHUM SALOMÃO 3 , DALMO LOPES DE SIQUEIRA 3 , LUIZ ALEXANDRE PETERNELLI 4 , PAULO CEZAR CAVATTE 5 RESUMO -Objetivou-se, neste trabalho, avaliar os componentes de produção e o ciclo de bananeiras tratadas com paclobutrazol (PBZ). Foram testadas cinco doses de PBZ (0,0; 0,5; 1,0; 1,5; e 2,0 g planta -1 ), aplicadas sobre o solo em torno das bananeiras 'Prata-Anã' e 'FHIA-01', aos quatro meses após o plantio. Os dados foram obtidos durante o primeiro ciclo, e os cachos foram colhidos quando os primeiros frutos apresentaram a cor da casca amarela. O ciclo médio foi de 507 dias, não diferindo em função de doses e cultivares. O PBZ reduziu o porte das plantas das duas cultivares. O aumento das doses de PBZ aumentou o número de folhas ativas na época da emissão da inflorescência da 'Prata-Anã', mas os efeitos sobre o cacho foram prejudiciais, com redução do número, do comprimento comercial e do diâmetro dos frutos, o que provocou redução na massa dos cachos e na produtividade. Na cultivar FHIA-01, o PBZ conferiu redução do porte das plantas e melhor sustentação do cacho, não influenciando na produtividade da cultura. A dose mais indicada de PBZ na bananeira 'FHIA 01' está em torno de 1,0 g planta -1 . Para a 'Prata-Anã', não se recomenda o uso de PBZ. Termos para indexação: Musa spp.; regulador de crescimento; produtividade.
In earlier-maturing coffee clones, owing to the shorter time required for fruit filling and ripen... more In earlier-maturing coffee clones, owing to the shorter time required for fruit filling and ripening, photoassimilates should be transported to fruits in a period shorter than that found in intermediate-or late-maturing clones. We hypothesised that at a given source-to-sink ratio, a presumably greater sink strength in early-maturing clones relative to intermediate-and late-maturing individuals should be correlated to increased rate of net carbon assimilation (A) and greater photo-assimilate transport to the fruits. Overall, earlier-maturing clones displayed greater A rates than the intermediate-maturing clones, which, in turn, had higher A than their late counterparts. Changes in A were largely associated with changes in stomatal conductance. Only marginal alterations occurred in the internal-to-ambient CO 2 concentration ratio, the carbon isotope composition ratio, soluble sugars and chlorophyll a fluorescence parameters. Some changes in starch pools were detected among treatments. To the best of our knowledge, this is the first report showing evidence that increased precociousness of fruit growth and maturation results in higher A and thus increased source strength, a fact associated to a large degree with higher stomatal aperture.
In this study, the combined effects of light and water availability on the functional relationshi... more In this study, the combined effects of light and water availability on the functional relationships of the relative growth rate (RGR), leaf chemical composition, construction and maintenance costs, and benefits in terms of payback time for Coffea arabica are presented. Coffee plants were grown for 8 months in 100% or 15% full sunlight and then a four-month water shortage was implemented. Plants grown under full sunlight were also transferred to shade and vice versa. Overall, most of the traits assessed were much more responsive to the availability of light than to the water supply. Larger construction costs (12%), primarily associated with elevated phenol and alkaloid pools, were found under full sunlight. There was a positive correlation between these compounds and the RGR, the mass-based net carbon assimilation rate and the carbon isotope composition ratio, which, in turn, correlated negatively with the specific leaf area. The payback time was remarkably lower in the sun than in shade leaves and increased greatly in water-deprived plants. The differences in maintenance costs among the treatments were narrow, with no significant impact on the RGR, and there was no apparent trade-off in resource allocation between growth and defence. The current irradiance during leaf bud formation affected both the specific leaf area and leaf physiology upon transferring the plants from low to high light and vice versa. In summary, sun-grown plants fixed more carbon for growth and secondary metabolism, with the net effect of an increased RGR.
Based on indirect evidence, it was previously suggested that shading could attenuate the negative... more Based on indirect evidence, it was previously suggested that shading could attenuate the negative impacts of drought on coffee (Coffea arabica), a tropical crop species native to shady environments. A variety (47) of morphological and physiological traits were examined in plants grown in 30-l pots in either full sunlight or 85% shade for 8 months, after which a 4-month water shortage was implemented. Overall, the traits showed weak or negligible responses to the light × water interaction, explaining less than 10% of the total data variation. Only slight variations in biomass allocation were observed in the combined shade and drought treatment. Differences in relative growth rates were mainly associated with physiological and not with morphological adjustments. In high light, drought constrained the photosynthetic rate through stomatal limitations with no sign of apparent photoinhibition; in low light, such constraints were apparently linked to biochemical factors. Sun-grown plants d...
The economics of coffee plantations is intrinsically linked to pruning, which can improve the can... more The economics of coffee plantations is intrinsically linked to pruning, which can improve the canopy architecture and thereby increase productivity. However, recommended pruning times on conilon coffee plantations have been made on an entirely empirical basis. In this study, by evaluating growth, photosynthetic gas exchanges, starch accumulation and crop productivity, the effects of pruning at different times between harvest and flowering were investigated for six conilon coffee clones with distinct stages of fruit maturation (early, intermediate and late). Clones with an early maturation stage were pruned at four different times: 0, 30, 60 and 90 days after harvest (DAH). Intermediate clones were pruned at 0, 30 and 60 DAH, and late clones were pruned at 0 and 30 DAH. Overall, the rates of shoot growth and net photosynthesis, the stomatal conductance and the crop yield were not affected by the pruning treatments in any of the clones. In addition, pruning times did not affect the concentrations of starch or the photochemical efficiency of photosystem II. The carbon isotope composition ratio was marginally affected by the treatments. These results suggest that the pruning time after harvests is relatively unimportant and pruning operations can be scheduled to optimise the use of labour, which directly impacts the production costs of coffee.
This study had three objectives: i) to observe maize inbred lines response to nitrogen (N) and ph... more This study had three objectives: i) to observe maize inbred lines response to nitrogen (N) and phosphorus (P) acquisition as well as their utilization efficiencies and traits of root morphology in contrasting levels of these nutrients, ii) to study the relationship between root morphology and nutrient use efficiencies for both nutrients, and iii) to identify contrasting parents with components N and P use efficiency for an inheritance study. We evaluated 15 inbred lines in two experiments conducted in contrasting conditions of N and P. We evaluated the shoot, root traits and nutritional efficiencies and observed the genetic variability for most traits. Selection can be practiced for most of these traits in specific environments. Under conditions of nutritional stress, average and heritability estimates were of lesser magnitude. In this study, the shoot and root morphology traits were shown to be associated with the acquisition efficiency of both N and P in all of the environments that were evaluated.
The effects of varying intensities of light on plants depend on when they occur, even if the tota... more The effects of varying intensities of light on plants depend on when they occur, even if the total amount of light received is kept constant. We designed an experiment using two clones of robusta coffee (Coffea canephora) intercropped with shelter trees in such a way that allowed us to compare coffee bushes shaded in the morning (SM) with those shaded in the afternoon (SA), and then confronting both with bushes receiving full sunlight over the course of the day (FS). The SM bushes displayed better gas-exchange performance than their SA and FS counterparts, in which the capacity for CO2 fixation was mainly constrained by stomatal (SA bushes) and biochemical (FS bushes) factors. Physiological traits associated with light capture were more responsive to temporal fluctuations of light rather than to the amount of light received, although this behavior could be a clone-specific response. The activity of key antioxidant enzymes differed minimally when comparing the SM and SA clones, but was much larger in FS clones. No signs of photoinhibition or cell damage were found regardless of the light treatments. Acclimations to varying light supplies had no apparent additional cost for constructing and maintaining the leaves regardless of the light supply. Both the SM and SA individuals displayed higher return in terms of revenue streams (e.g. higher mass-based light-saturated photosynthetic rates, photosynthetic nitrogen use efficiencies and long-term water use efficiencies) than their FS counterparts. In conclusion, shading may improve the physiological performance of coffee bushes growing in harsh, tropical environments.
Resende, R. S., Rodrigues, F. Á., Cavatte, P. C., Martins, S. C. V., Moreira, W. R., Chaves, A. R... more Resende, R. S., Rodrigues, F. Á., Cavatte, P. C., Martins, S. C. V., Moreira, W. R., Chaves, A. R. M., and DaMatta, F. M. 2012. Leaf gas exchange and oxidative stress in sorghum plants supplied with silicon and infected by Colletotrichum sublineolum. Phytopathology 102:892-898.
Crop Breeding and Applied Biotechnology (Online), 2011
This study aimed to verify the relationship between breeding for tolerance to low levels of soil ... more This study aimed to verify the relationship between breeding for tolerance to low levels of soil nutrients and for nutrient use efficiency in tropical maize. Fifteen inbred lines were evaluated in two greenhouse experiments under contrasting levels of N and P. The relationship between nutritional efficiency and tolerance to nutritional stress was estimated by the Spearman ranking correlation between the genotypes for the traits related to N and P use efficiency and phenotypic plasticity indices. The lack of relationship between the traits, in magnitude as well as significance, indicates that these characters are controlled by different gene groups. Consequently, simultaneous selection for both nutrient use efficiency and tolerance to nutritional stress is possible, if the mechanisms that confer efficiency and tolerance are not competitive.
Key message This study highlights that wood density integrates the xylem structural changes and p... more Key message This study highlights that wood density integrates the xylem structural changes and plays a key role in drought tolerance at the intraspecific level in clones of robusta coffee. Abstract Robusta coffee (Coffea canephora) is largely cropped in regions where drought stress is the major bottleneck limiting crop yields. We hypothesized that clonal differences in wood density (D w ) would be reflected in xylem anatomical differences with associated consequences for hydraulic functioning and ultimately drought tolerance. We assessed the major functional properties of water conduction systems at both the leaf and stem levels in 8-year-old clones of robusta coffee with varying degrees of drought tolerance. The plants were grown outdoors in 24-L pots and either irrigated or subjected to a 4-month water deficit. Upon drought imposition, increased D w , primarily associated with a rearrangement of the fiber matrix and secondarily associated with narrower vessels (although more numerous per cross-sectional area), was correlated with tolerance to hydraulic dysfunctions. Some coordination at the leaf level concerning hydraulic and stomatal anatomical patterns, with stem structural properties, was observed under ample irrigation, but this coordination was decoupled by the imposed drought stress. In conclusion, our data suggest a role for D w in drought tolerance in coffee; however, drought tolerance implies that clones that successfully thrive under low water supply might have compromised fitness under ample irrigation, suggesting a trade-off between D w and the conduction capacity in coffee.
Resumo -A presença de sais interfere no potencial hídrico do solo, reduzindo o gradiente potencia... more Resumo -A presença de sais interfere no potencial hídrico do solo, reduzindo o gradiente potencial entre o solo e a superfície da semente, restringindo a absorção de água pela superfície da semente, podendo influenciar significativamente no processo germinativo.O presente trabalho teve como objetivo avaliar o estresse salino sobre a germinação e o vigor de sementes de tomate (Lycopersicon esculentum M.). Os potencias osmóticos das soluções utilizadas foram 0,0 (controle); -0,4; -0,8; -1,2; -1,6 MPa, obtidos com NaCl como soluto, aplicado no substrato rolo de papel germitest, equivalente a 2,5 vezes o peso do papel, sendo os rolos mantidos nas temperaturas de 20, 20-30 e 30ºC, formando um esquema fatorial 5 X 3 (concentrações salinas X temperaturas). O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições. A avaliação do experimento foi feita através da porcentagem e do índice de velocidade de germinação, matéria fresca e seca da parte aérea e do si...
This study aimed to evaluate under photoautotrophic conditions the effect of CO2-enriched atmosph... more This study aimed to evaluate under photoautotrophic conditions the effect of CO2-enriched atmosphere (360 or 1,000 μmol CO2 mol−1 air) combined with two substrate types (agar or Florialite®) in vitro on plants of Pfaffia glomerata, an endangered medicinal species with promising applications in phytotherapy and phytomedicine. The effects of the treatments on the growth, stomatal density, Rubisco activity, carbon isotopic discrimination, metabolite accumulation, photosynthetic pigments and ultrastructural characteristics were investigated. After a 35-day cultivation period, the in vitro-growth of P. glomerata nodal segments under the different treatments resulted in plants with substantial differences in relation to their growth, photosynthetic pigments, stomatal density and leaf ultrastructural characteristics. The enrichment with CO2 coupled with a porous substrate increased the growth of P. glomerata. The stomatal density in the abaxial epidermis more than doubled in response to th...
Acclimations to low and high light levels are located in opposite extremes. We examined how the c... more Acclimations to low and high light levels are located in opposite extremes. We examined how the coffee plant (Coffea arabica), which is considered to be shade-demanding although it performs well under full sun exposure, can acclimate to a range of light regimens. We hypothesised that the growth and physiological performance depends on the total amount of light received by the plant per day and on the temporal order of diurnal variations in the light supply. The biomass accumulation and allocation and the key photosynthetic traits of pot-grown coffee seedlings were examined over a range of light treatments as follows: plants grown entirely under 100%, 40% or 10% sunlight; plants grown at either 40% or 10% sunlight from sunrise to midday and then submitted to full sunlight until sunset; and plants grown under full sunlight from sunrise to midday and then submitted to either 40% or 10% sunlight throughout the afternoon. The total biomass increased linearly with the increasing total lig...
Dentre as condições ideais para germinação, o tipo de solo é muito importante, pois, interfere nã... more Dentre as condições ideais para germinação, o tipo de solo é muito importante, pois, interfere não apenas na germinação das sementes mas, também, no desenvolvimento pós-seminal. Além da adubação, outro fator importante na emergência e crescimento das mudas é a luminosidade devido sua influência em processos como a fotossíntese. Neste trabalho, objetivou-se avaliar a influência da adubação com esterco bovino, torta de filtro e vinhaça, bem como da luminosidade na germinação e vigor de sementes de cenoura, em solo de mineração de calcário. O experimento foi conduzido em casa de vegetação, em 2005, em Alegre-ES. Utilizou-se o delineamento inteiramente casualizado, em arranjo fatorial 13 x 3 (adubações x luminosidades) e 4 repetições. Os tratamentos constaram de solo de mineração de calcário enriquecido ou não com adubação e 3 níveis de luminosidade. A adubação teve influência direta nas plântulas, pois, as menores intensidades (13.8 mol fótons m -2 s -1 ) aumentaram a germinação e altura destas, enquanto as maiores intensidades (1192.8 mol fótons m -2 s -1 ) aumentaram a velocidade de germinação e o acúmulo de matéria seca. A adubação com os 3 materiais orgânicos e NPK proporcionou maior altura e matéria seca às plantas.
... Heder Braun1; José Carlos Lopes2*; Leandro Torres de Souza3; Edilson Romais Schmildt4; Rithie... more ... Heder Braun1; José Carlos Lopes2*; Leandro Torres de Souza3; Edilson Romais Schmildt4; Rithiely Paschoa Queiroz Cavatte5; Paulo Cezar Cavatte6 ... A avaliação foi feita pela porcentagem de germinação, massa fresca e seca de plântulas, aos 65 dias após a semeadura. ...
... Heder Braun 1 ; Paulo Cezar Cavatte 2 ; José Augusto Teixeira do Amaral 3 ; José Francisco Te... more ... Heder Braun 1 ; Paulo Cezar Cavatte 2 ; José Augusto Teixeira do Amaral 3 ; José Francisco Teixeira do Amaral 3 ; Edvaldo Fialho dos ... Aos 18 dias após o plantio das estacas foi analisada a porcentagem de enraizamento (ENR), determinada através da proporção de estacas ...
Plants are often exposed to several adverse environmental conditions that potentially generate st... more Plants are often exposed to several adverse environmental conditions that potentially generate stress and thus negatively affect their growth and productivity. Understanding the physiological responses of crops to stress conditions is essential to minimizing the deleterious impacts of stress and maximizing productivity. Therefore, there is urgent need for more scientific research to increase our understanding of the physiological behavior of crops in response not only to a specific type of stress but also to multiple interacting stressors, such as water, and thermal stresses. The proper assessment of this information may result in important tools for monitoring the most promising genetic material in plant breeding programs. In this chapter, the plant strategies associated with satisfactory growth and yield under abiotic stress conditions are discussed, with emphasis in tropical environments. In addition, the state of the art on the physiology of the major abiotic stresses (drought, salinity, heat, nitrogen and phosphorus deficiencies and aluminum toxicity) and possible strategies to develop cultivars with
RITHIELY PASCHOA QUEIROZ CAVATTE 2 , LUIZ CARLOS CHAMHUM SALOMÃO 3 , DALMO LOPES DE SIQUEIRA 3 , ... more RITHIELY PASCHOA QUEIROZ CAVATTE 2 , LUIZ CARLOS CHAMHUM SALOMÃO 3 , DALMO LOPES DE SIQUEIRA 3 , LUIZ ALEXANDRE PETERNELLI 4 , PAULO CEZAR CAVATTE 5 RESUMO -Objetivou-se, neste trabalho, avaliar os componentes de produção e o ciclo de bananeiras tratadas com paclobutrazol (PBZ). Foram testadas cinco doses de PBZ (0,0; 0,5; 1,0; 1,5; e 2,0 g planta -1 ), aplicadas sobre o solo em torno das bananeiras 'Prata-Anã' e 'FHIA-01', aos quatro meses após o plantio. Os dados foram obtidos durante o primeiro ciclo, e os cachos foram colhidos quando os primeiros frutos apresentaram a cor da casca amarela. O ciclo médio foi de 507 dias, não diferindo em função de doses e cultivares. O PBZ reduziu o porte das plantas das duas cultivares. O aumento das doses de PBZ aumentou o número de folhas ativas na época da emissão da inflorescência da 'Prata-Anã', mas os efeitos sobre o cacho foram prejudiciais, com redução do número, do comprimento comercial e do diâmetro dos frutos, o que provocou redução na massa dos cachos e na produtividade. Na cultivar FHIA-01, o PBZ conferiu redução do porte das plantas e melhor sustentação do cacho, não influenciando na produtividade da cultura. A dose mais indicada de PBZ na bananeira 'FHIA 01' está em torno de 1,0 g planta -1 . Para a 'Prata-Anã', não se recomenda o uso de PBZ. Termos para indexação: Musa spp.; regulador de crescimento; produtividade.
In earlier-maturing coffee clones, owing to the shorter time required for fruit filling and ripen... more In earlier-maturing coffee clones, owing to the shorter time required for fruit filling and ripening, photoassimilates should be transported to fruits in a period shorter than that found in intermediate-or late-maturing clones. We hypothesised that at a given source-to-sink ratio, a presumably greater sink strength in early-maturing clones relative to intermediate-and late-maturing individuals should be correlated to increased rate of net carbon assimilation (A) and greater photo-assimilate transport to the fruits. Overall, earlier-maturing clones displayed greater A rates than the intermediate-maturing clones, which, in turn, had higher A than their late counterparts. Changes in A were largely associated with changes in stomatal conductance. Only marginal alterations occurred in the internal-to-ambient CO 2 concentration ratio, the carbon isotope composition ratio, soluble sugars and chlorophyll a fluorescence parameters. Some changes in starch pools were detected among treatments. To the best of our knowledge, this is the first report showing evidence that increased precociousness of fruit growth and maturation results in higher A and thus increased source strength, a fact associated to a large degree with higher stomatal aperture.
In this study, the combined effects of light and water availability on the functional relationshi... more In this study, the combined effects of light and water availability on the functional relationships of the relative growth rate (RGR), leaf chemical composition, construction and maintenance costs, and benefits in terms of payback time for Coffea arabica are presented. Coffee plants were grown for 8 months in 100% or 15% full sunlight and then a four-month water shortage was implemented. Plants grown under full sunlight were also transferred to shade and vice versa. Overall, most of the traits assessed were much more responsive to the availability of light than to the water supply. Larger construction costs (12%), primarily associated with elevated phenol and alkaloid pools, were found under full sunlight. There was a positive correlation between these compounds and the RGR, the mass-based net carbon assimilation rate and the carbon isotope composition ratio, which, in turn, correlated negatively with the specific leaf area. The payback time was remarkably lower in the sun than in shade leaves and increased greatly in water-deprived plants. The differences in maintenance costs among the treatments were narrow, with no significant impact on the RGR, and there was no apparent trade-off in resource allocation between growth and defence. The current irradiance during leaf bud formation affected both the specific leaf area and leaf physiology upon transferring the plants from low to high light and vice versa. In summary, sun-grown plants fixed more carbon for growth and secondary metabolism, with the net effect of an increased RGR.
Based on indirect evidence, it was previously suggested that shading could attenuate the negative... more Based on indirect evidence, it was previously suggested that shading could attenuate the negative impacts of drought on coffee (Coffea arabica), a tropical crop species native to shady environments. A variety (47) of morphological and physiological traits were examined in plants grown in 30-l pots in either full sunlight or 85% shade for 8 months, after which a 4-month water shortage was implemented. Overall, the traits showed weak or negligible responses to the light × water interaction, explaining less than 10% of the total data variation. Only slight variations in biomass allocation were observed in the combined shade and drought treatment. Differences in relative growth rates were mainly associated with physiological and not with morphological adjustments. In high light, drought constrained the photosynthetic rate through stomatal limitations with no sign of apparent photoinhibition; in low light, such constraints were apparently linked to biochemical factors. Sun-grown plants d...
The economics of coffee plantations is intrinsically linked to pruning, which can improve the can... more The economics of coffee plantations is intrinsically linked to pruning, which can improve the canopy architecture and thereby increase productivity. However, recommended pruning times on conilon coffee plantations have been made on an entirely empirical basis. In this study, by evaluating growth, photosynthetic gas exchanges, starch accumulation and crop productivity, the effects of pruning at different times between harvest and flowering were investigated for six conilon coffee clones with distinct stages of fruit maturation (early, intermediate and late). Clones with an early maturation stage were pruned at four different times: 0, 30, 60 and 90 days after harvest (DAH). Intermediate clones were pruned at 0, 30 and 60 DAH, and late clones were pruned at 0 and 30 DAH. Overall, the rates of shoot growth and net photosynthesis, the stomatal conductance and the crop yield were not affected by the pruning treatments in any of the clones. In addition, pruning times did not affect the concentrations of starch or the photochemical efficiency of photosystem II. The carbon isotope composition ratio was marginally affected by the treatments. These results suggest that the pruning time after harvests is relatively unimportant and pruning operations can be scheduled to optimise the use of labour, which directly impacts the production costs of coffee.
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