Scientia Agrícola
URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/12094
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Item Comparison between climatological and field water balances for a coffee crop(Escola Superior de Agricultura "Luiz de Queiroz", 2007-05) Bruno, Isabeli Pereira; Silva, Adriana Lúcia da; Reichardt, Klaus; Dourado-Neto, Durval; Bacchi, Osny Oliveira Santos; Volpe, Clóvis AlbertoThe use of climatological water balances in substitution to complete water balances directly measured in the field allows a more practical crop management, since the climatological water balances are based on data monitored as a routine. This study makes a comparison between these methods in terms of estimatives of evapotranspiration, soil water storage, soil available water, runoff losses, and drainage below root zone, during a two year period, taking as an example a coffee crop of the variety Catuaí, three to five years old. Climatological water balances based on the estimation of the evapotranspiration through the methods of Thornthwaite and Penman-Monteith, can reasonably substitute field measured balances, however underestimating the above mentioned variables.Item Spatial variability of leaf wetness duration in cotton, coffee and banana crop canopies(Escola Superior de Agricultura "Luiz de Queiroz", 2008-12) Santos, Eduardo Alvarez; Sentelhas, Paulo Cesar; Pezzopane, José Eduardo Macedo; Angelocci, Luiz Roberto; Monteiro, José Eduardo Boffino AlmeidaDespite the importance of leaf wetness duration for plant disease epidemiology, there has been little attention paid to research on how its variability relates to different cropping situations. The objective of this study was to evaluate the spatial variability of leaf wetness duration (LWD) in three crops, comparing these measurements with turfgrass LWD, obtained in a standard weather station. LWD was measured by electronic sensors in three crops with different canopy structures and leaf area: cotton, coffee and banana. For the cotton crop, cylindrical sensors were deployed at the lower third and on the top of the canopy, facing southwest. For the coffee crop, flat plate sensors were installed in the lower third of the canopy facing northeast and southwest; in the middle third facing northeast and southwest; and inside and on the top of the canopy. For the banana canopy, cylindrical sensors were used to measure LWD in the lower third of the canopy and in the upper third of the plant. Turfgrass LWD was simultaneously measured in a nearby standard weather station. The LWD showed different patterns of variation in the three crop canopies. For coffee plants, the longest LWD was found in the lower portions of the canopy; for the banana crop, the upper third of the canopy showed the longest LWD; whereas for the cotton crop no difference was observed between the top and lower third of the canopy. Turfgrass LWD presented a good relationship with LWD measured on the top or in the upper third of the crops. Thus, the estimate of crop LWD can be perfomed based on turfgrass LWD, this being a useful tool for plant disease management purposes for crops in which the longer LWD occurs at the upper canopy portion.Item Total phenol concentrations in coffee tree leaves during fruit development(Escola Superior de Agricultura "Luiz de Queiroz", 2008-07) Salgado, Paula Rodrigues; Favarin, José Laércio; Leandro, Roseli Aparecida; Lima Filho, Oscar Fontão deVegetables have a natural defense against external factors synthesizing phenolic compounds, which depends on the maturity stage and on the climate. Total phenol grades were extracted from mature and young coffee leaves and were analyzed in relation to yield, phenology and climate. The climatic conditions were described by air temperature, global radiation and daily insolation. Evaluations were made on height, diameter and length of reproductive branches to determine the respective vegetative growth rates of the plants. The amounts of total phenols in the plants at the production stage was 174.0 mg g -1 and 138.9 mg g -1 for young and mature leaves, respectively, and for plants without fruit formation 186.5 mg g -1 and 127.6 mg g -1 for young and mature leaves, respectively. The total phenol concentrations in young leaves with and without fruit formation were 25% and 46% greater compared to mature leaves. The secondary phenol synthesis in seed (146.8 mg g -1 ) was 31% lower than during grain maturation (212.4 mg g -1 ). The total phenol metabolization depends indirectly on the temperature and on the global radiation, presenting an inverse trend in relation to these climatic variables. Crop protection management should take into consideration periods of endanger of this natural defense of the plant.Item Variability of water balance components in a coffee crop in Brazil(Escola Superior de Agricultura "Luiz de Queiroz", 2006-03) Silva, Adriana Lúcia da; Roveratti, Renato; Reichardt, Klaus; Bacchi, Osny Oliveira Santos; Timm, Luis Carlos; Bruno, Isabeli Pereira; Oliveira, Julio César Martins; Dourado Neto, DurvalEstablishing field water balances is difficult and costly, the variability of their components being the major problem to obtain reliable results. This component variability is presented herein for a coffee crop grown in the Southern Hemisphere, on a tropical soil with 10% slope. It was observed that: rainfall has to be measured with an appropriate number of replicates; irrigation can introduce great variability into calculations; evapotranspiration, calculated as a remainder of the water balance equation, has exceedingly high coefficients of variation; the soil water storage component is the major contributor in error propagation calculations to estimate evapotranspiration; and that runoff can be satisfactorily controlled on the 10% slope through crop management practices.Item Numerical modeling of actual evapotranspiration of a coffee crop(Escola Superior de Agricultura "Luiz de Queiroz", 2011-07) Cesanelli, Andrés; Guarracino, LuisThe evapotranspiration estimation has great importance to crop productivity and agricultural water management. In this study, evapotranspiration is analyzed in a coffee (Coffea arabica L.) crop located in Piracicaba, state of São Paulo (Brazil) using a numerical method based on the simulation of both water flow and crop activity in the unsaturated zone of the soil. Actual evapotranspiration is estimated from potential evapotranspiration using water stress functions, meteorological data, soil hydraulic parameters, crop coefficients and leaf area index values. Crop transpiration and soil evaporation are individually quantified improving the analysis of the evapotranspiration process. The numerical procedure can predict periods of crop water stress and becomes an attractive tool to analyze the effect of non-standard conditions on coffee crops and to design efficient irrigation schedules. Simulated evapotranspiration values are in good agreement with experimental values determined in the study site.Item Stomatal behavior and components of the antioxidative system in coffee plants under water stress(Escola Superior de Agricultura "Luiz de Queiroz", 2011-01) Deuner, Sidnei; Alves, José Donizeti; Zanandrea, Ilisandra; Goulart, Patrícia de Fátima Pereira; Silveira, Neidiquele Maria; Henrique, Paôla de Castro; Mesquita, Alessandro CarlosCoffee (Coffea arabica) plants show a positive relationship between stomatal closure and formation and accumulation of H2O2. However, for coffee plants under water restriction such relationship has never been studied. The objective of the present study was evaluate the stomatal movement and the antioxidant capacity of coffee seedlings under different water regimes. Eight months old coffee seedlings of cv. Catuaí IAC 99 were submitted to field capacity, gradual and total suspension of irrigation during a period of 21 days. Evaluations of leaf water potential (Ψ w) were performed in the beginning of the morning, and stomatal resistance, transpiration rate and vapor pressure deficit were determined at 10 am and 5 pm. All biochemical and enzymatic determinations were performed in leaves collected at 5 pm. Evaluations and samplings were performed at three days intervals. There was no variation in Ψ w during the evaluated period for plants in field capacity. However, an expressive decrease of Ψ w following day 12, reaching values near -2.5 MPa at the end of the experiment was observed for plants submitted to gradual suspension of irrigation. For plants submitted to total suspension of irrigation, Ψ w decreases after the sixth day, reaching -2.5 MPa at day 15. The decay of Ψ w in plants submitted to gradual and total suspension of irrigation reflected in increased stomatal resistance and in a decreased transpiration rate leading to an increase in hydrogen peroxide formation and, on final stages, increase in lipid peroxidation. As a conclusion, an increase in the activity of antioxidant enzymes as well as in the levels of ascorbate and dehydroascorbate was observed, which act in the detoxification of free radicals formed as result of the water stress.Item Invertase and sucrose synthase activities in coffee plants sprayed with sucrose solution(Escola Superior de Agricultura "Luiz de Queiroz", 2003-04) Silva, José Carlos da; Alves, José Donizeti; Alvarenga, Amauri Alves de; Magalhães, Marcelo Murad; Livramento, Dárlan Einstein do; Fries, Daniela DeitosOne management practice of which the efficiency has not yet been scientifically tested is spraying coffee plants with diluted sucrose solutions as a source of carbon for the plant. This paper evaluates the effect of foliar spraying with sugar on the endogenous level of carbohydrates and on the activities of invertase and sucrose synthase in coffee (Coffea arabica L.) seedlings with reduced (low) and high (normal) levels of carbon reserve. The concentrations used were 0.5 and 1.0% sucrose, and water as a control. The use of sucrose at 1.0% caused an increase in the concentration of total soluble sugars in depauperate plants, as well as increased the activity of the following enzymes: cell wall and vacuole acid invertase, neutral cytosol invertase and sucrose synthase. In plants with high level of carbon reserve, no increments in total soluble sugar levels or in enzymatic activity were observed. Regardless of treatments or plants physiological state, no differences in transpiration or stomatal conductance were observed, demonstrating the stomatal control of transpiration. Photosynthesis was stimulated with the use of 0.5 and 1.0 % sucrose only in depauperate plants. Coffee seedling spraying with sucrose is only efficient for depauperate plants, at the concentration of 1.0%.