oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 21 )

2018 ( 25 )

2017 ( 28 )

2016 ( 34 )

Custom range...

Search Results: 1 - 10 of 22054 matches for " Paulo Cezar Rezende;Ronchi "
All listed articles are free for downloading (OA Articles)
Page 1 /22054
Display every page Item
Critical values of nitrogen indices in tomato plants grown in soil and nutrient solution determined by different statistical procedures
Fontes, Paulo Cezar Rezende;Ronchi, Cláudio Pagotto;
Pesquisa Agropecuária Brasileira , 2002, DOI: 10.1590/S0100-204X2002001000010
Abstract: the objective of this study was to establish critical values of the n indices, namely soil-plant analysis development (spad), petiole sap n-no3 and organic n in the tomato leaf adjacent to the first cluster (lac), under soil and nutrient solution conditions, determined by different statistical approaches. two experiments were conducted in randomized complete block design with four repli-cations. tomato plants were grown in soil, in 3 l pot, with five n rates (0, 100, 200, 400 and 800 mg kg-1) and in solution at n rates of 0, 4, 8, 12 and 16 mmol l-1. experiments in nutrient solution and soil were finished at thirty seven and forty two days after transplanting, respectively. at those times, spad index and petiole sap n-no3 were evaluated in the lac. then, plants were harvested, separated in leaves and stem, dried at 70oc, ground and weighted. the organic n was determined in lac dry matter. three statistical procedures were used to calculate critical n values. there were accentuated discrepancies for critical values of n indices obtained with plants grown in soil and nutrient solution as well as for different statistical procedures. critical values of nitrogen indices at all situations are presented.
Critical values of nitrogen indices in tomato plants grown in soil and nutrient solution determined by different statistical procedures
Fontes Paulo Cezar Rezende,Ronchi Cláudio Pagotto
Pesquisa Agropecuária Brasileira , 2002,
Abstract: The objective of this study was to establish critical values of the N indices, namely soil-plant analysis development (SPAD), petiole sap N-NO3 and organic N in the tomato leaf adjacent to the first cluster (LAC), under soil and nutrient solution conditions, determined by different statistical approaches. Two experiments were conducted in randomized complete block design with four repli-cations. Tomato plants were grown in soil, in 3 L pot, with five N rates (0, 100, 200, 400 and 800 mg kg-1) and in solution at N rates of 0, 4, 8, 12 and 16 mmol L-1. Experiments in nutrient solution and soil were finished at thirty seven and forty two days after transplanting, respectively. At those times, SPAD index and petiole sap N-NO3 were evaluated in the LAC. Then, plants were harvested, separated in leaves and stem, dried at 70oC, ground and weighted. The organic N was determined in LAC dry matter. Three statistical procedures were used to calculate critical N values. There were accentuated discrepancies for critical values of N indices obtained with plants grown in soil and nutrient solution as well as for different statistical procedures. Critical values of nitrogen indices at all situations are presented.
Podrid o apical do tomate, queima dos bordos das folhas de alface e depress o amarga dos frutos em ma : deficiência de Ca?
Fontes Paulo Cezar Rezende
Horticultura Brasileira , 2003,
Abstract:
índices agron?micos do meloeiro associados à dose adequada de nitrogênio, em ambiente protegido e no campo
Coelho, Evando Luiz;Fontes, Paulo Cezar Rezende;
Ciência e Agrotecnologia , 2005, DOI: 10.1590/S1413-70542005000500009
Abstract: the objective of the experiments was to determine the values of the agronomical melon (cucumis melo l.) leaf indices, represented by both area (fla) and dry weight (flw) of the fifth leaf from the apex associated with the nitrogen rate for the maximum melon fruit yield (mfy), at two samples dates and two environmental conditions. two experiments, in unheated greenhouse and field conditions, were carried out with similar procedures. each experiment consisted of four randomized blocks containing five treatments or five nitrogen rates (0, 75, 150, 300, and 450 kg ha-1 of n), applied as urea. part of the fertilizer was placed in furrows (30%), before seedling transplantation, and the remaining 70% were trickle-applied through part of the plant cycle. initially, 14 days after transplantation, plant chlorosis intensity was evaluated by scores from 0 (no chlorosis) to 5 (leaves completely chlorotics). at 25 and 53 days after transplantation, at first and second fruit setting, fla and flw were determined. at both experiments, chlorosis intensity decreased, fla and flw increased with increasing n rates. chlorosis intensity values associated with mfy were 0.22 and 1.11 at greenhouse and field, respectively. in the greenhouse, at first and second sampling dates, fla values associated with mfy were 107 and 72 cm2 and flw values were 0.36 and 0.26 g, respectively. in the field, the corresponding values were 89 and 69 cm2 and 0.39 and 0.30 g, respectively. these are proposed melon plant index values indicators of the added n fertilizer rate adequacy.
Predi??o da produ??o do tomateiro cultivado em ambiente protegido e no campo
Araujo, Charles de;Fontes, Paulo Cezar Rezende;Sediyama, Carlos Sigueyuki;
Ciência e Agrotecnologia , 2007, DOI: 10.1590/S1413-70542007000100015
Abstract: the tomato plant yield of the first five clusters was used in the development of mathematical model to estimate yield obtained in nine trusses. six experiments were carried out, being four in unheated greenhouse (a, b, c and d) and two in the field (e and f), in the federal university of vi?osa. all the experiments consisted of ten treatments with differentiated n rates that ranged from 0 to 1,953.7 kg./ha-1. the data up to the 1st, 2nd, 3rd, 4th and 5th trusses accumulated total yield of the experiments c and e were submitted to the analysis of variance and regression models and were adjusted to 9th trusses accumulated yield. the proposed models validity was based on the correlation (r) among the observed and estimated data by the model and by the medium square deviations (msd) analysis and its additive components. the proposed models, based on the yield accumulated until 5th trusses were precise in estimate the total fruits yield accumulated in the tomato plant with 9 trusses in unheated greenhouse and field. the models should be compared and validated with data of other studies. the medium square deviations (msd) analysis and its components are useful to verify the regression models validity through the model deviations quantification and identication causes of those deviations.
Fruit size, mineral composition and quality of trickle-irrigated tomatoes as affected by potassium rates
Fontes, Paulo Cezar Rezende;Sampaio, Regynaldo Arruda;Finger, Fernando Luiz;
Pesquisa Agropecuária Brasileira , 2000, DOI: 10.1590/S0100-204X2000000100003
Abstract: an experiment was conducted to determine the fruit size, mineral composition and quality of trickle-irrigated tomatoes as affected by potassium fertilizer rates. six potassium (k) rates were applied as kcl, corresponding to 0, 48.4, 118.6, 188.8, 259.0 and 399.4 kg ha-1, with four replicates, following a randomized block design. quadratic responses to k rates were observed for double extra large (diameter > 60 mm), extra large (56 to 60 mm) and large (52 to 56 mm) fruit yields. maximum yields of these classes were achieved with k rates of 116, 190 and 233 kg ha-1, respectively. fruit dry matter, phosphorus, sulfur and magnesium contents were not affected by k rates, but nitrate and k contents showed significant increments as k rates were increased. vitamin c, total soluble solids, lycopene and b-carotene contents in the fruits were not affected by k rates. increments in the k rate lowered the fruit ph and increased total acids content.
Tomato yield and potassium concentrations in soil and in plant petioles as affected by potassium fertirrigation
FONTES, PAULO CEZAR REZENDE;SAMPAIO, REGYNALDO ARRUDA;MANTOVANI, EVERARDO CHARTUNI;
Pesquisa Agropecuária Brasileira , 2000, DOI: 10.1590/S0100-204X2000000300013
Abstract: tomato (lycopersicon esculentum mill.) cv. santa clara was grown on a silt clay soil with 46 mg dm-3 mehlich 1 extractable k, to evaluate the effects of trickle-applied k rates on fruit yield and to establish k critical concentrations in soil and in plant petioles. six potassium rates (0, 48, 119, 189, 259 and 400 kg ha-1 k) were applied in a randomized complete block design with four replications. soil and plant k critical levels were determined at two plant growth stages (at the beginning of the second and fourth cluster flowering). total, marketable and weighted yields increased with k rates, reaching their maximum of 86.4, 73.4, and 54.9 ton ha-1 at 198, 194, and 125 kg ha-1 k , respectively. at the first soil sampling date k critical concentrations in the soil associated with k rates for maximum marketable and weighted yields were 92 and 68 mg dm-3, respectively. potassium critical concentrations in the dry matter of the petioles sampled by the beginning of the second and fourth cluster flowering time, associated with maximum weighted yield, were 10.30 and 7.30 dag kg-1, respectively.
Resposta do tomateiro à fertirriga??o potássica e cobertura plástica do solo
Sampaio, Regynaldo Arruda;Fontes, Paulo Cezar Rezende;Sediyama, Carlos Sigueyuki;
Pesquisa Agropecuária Brasileira , 1999, DOI: 10.1590/S0100-204X1999000100004
Abstract: the aim of this work was to determine the effects of fertirrigation with potassium and black polyethylene cover on tomato. a field experiment was carried out on a cambic yellowish podzolic at the universidade federal de vi?osa, in vi?osa, mg, brazil. the treatments, with five replicates, following a randomized block design, were: (a) manual application of 40% of recommended k rate at the seedling transplantation row and manual sidedress application of 60%; (b) manual application of 40% of recommended k rate at the seedling transplantation row and 60% by fertirrigation; (c) similar procedure to b but with black polyethylene cover; (d) application of 100% of k rate by fertirrigation and (e) similar procedure to d but with black polyethylene cover. treatments b, c, d and e were drip irrigated. tomato yields were higher with k application by fertirrigation than using the manual fertilization method, but the tomato yields were not influenced by k partial or total fertirrigation neither by black polyethylene cover. the no3-n, organic-n, k, ca and mg concentrations on leave petioles were not influenced by treatments.
Morfologia e parti??o de assimilados na batateira em fun??o de época de amostragem e de doses de potássio
Reis Júnior, Roberto dos Anjos;Fontes, Paulo Cezar Rezende;
Pesquisa Agropecuária Brasileira , 1999, DOI: 10.1590/S0100-204X1999000500010
Abstract: this study was conducted in order to evaluate potato (solanum tuberosum l.) morphology and dry matter partition in response to sampling time, k levels and its residue. six k levels (0, 60, 120, 240, 480 and 960 kg k2o ha-1) were applied in the field as potassium sulfate, in randomized blocks design, repeated four times. baraka potato tubers were seeded spaced 0.8 x 0.3 m. plants were sampled at 20 and 48 days after its emergence (dae) to estimate leaf area, stem length, number and fresh and dry matter yield of leaf, stem and tuber, and dry matter content of leaf and stem. only stem length increased with k fertilization, resulting in smaller overshadow of plant. in the first experiment, at 20 dae, potato was presenting, in media, 42 leaves, three stems, 5,389 cm2 of leaf area, 157.1 and 216.4 g of fresh matter of stem and leaf, respectively, and 6.2 and 9.2% of dry matter content of stem and leaf, respectively.
Tomato yield and potassium concentrations in soil and in plant petioles as affected by potassium fertirrigation
FONTES PAULO CEZAR REZENDE,SAMPAIO REGYNALDO ARRUDA,MANTOVANI EVERARDO CHARTUNI
Pesquisa Agropecuária Brasileira , 2000,
Abstract: Tomato (Lycopersicon esculentum Mill.) cv. Santa Clara was grown on a silt clay soil with 46 mg dm-3 Mehlich 1 extractable K, to evaluate the effects of trickle-applied K rates on fruit yield and to establish K critical concentrations in soil and in plant petioles. Six potassium rates (0, 48, 119, 189, 259 and 400 kg ha-1 K) were applied in a randomized complete block design with four replications. Soil and plant K critical levels were determined at two plant growth stages (at the beginning of the second and fourth cluster flowering). Total, marketable and weighted yields increased with K rates, reaching their maximum of 86.4, 73.4, and 54.9 ton ha-1 at 198, 194, and 125 kg ha-1 K , respectively. At the first soil sampling date K critical concentrations in the soil associated with K rates for maximum marketable and weighted yields were 92 and 68 mg dm-3, respectively. Potassium critical concentrations in the dry matter of the petioles sampled by the beginning of the second and fourth cluster flowering time, associated with maximum weighted yield, were 10.30 and 7.30 dag kg-1, respectively.
Page 1 /22054
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.