Abstract In order to carry out a retrospective analysis of successive follicular aspirations in brangus cows in a livestock establishment in the Alto Paraná department, records of 10 Brangus breed cows subjected to seven successive follicular aspirations without prior hormonal stimulation were used. In the same, the quantity and quality of oocytes obtained in the aspirations were evaluated. Regarding the number of aspirated oocytes, in an average interval of 45 days between aspirations, an average of 207 ± 14 oocytes was obtained. Statistical analysis was performed by making a random comparison between aspirations: first aspiration with fourth aspiration, finding no statistically significant differences (p> 0.05); then the 4th aspiration was compared with the 7th aspiration, resulting statistically significant (p <0.05). Regarding the number of viable oocytes per aspiration, an average of 206 ± 30 oocytes and 88 non-viable oocytes were obtained, which comparing the first with the fourth aspiration yield statistically significant results (p <0.05). Regarding oocyte quality, the results show a greater quantity of GIII oocytes, they were statistically analyzed in the following way: comparison between the first (22.4) and the fourth aspiration (20.1) of the quality of GI oocytes, GII, GIII, yielding statistically non-significant results (p> 0.05).

Resumen Con el objetivo de realizar un análisis retrospectivo de las aspiraciones foliculares sucesivas en vacas de la raza brangus en un establecimiento ganadero del departamento de Alto Paraná, fueron utilizados registros de 10 vacas de la raza Brangus sometidas a siete aspiraciones foliculares sucesivas sin previa estimulación hormonal. En el mismo fueron evaluadas la cantidad y calidad de ovocitos obtenidos en las aspiraciones. Con respecto a la cantidad de ovocitos aspirados, en intervalo promedio de 45 días entre aspiraciones, se obtuvo un promedio de 207± 14 ovocitos. Se realizó el análisis estadístico realizando una comparación al azar entre aspiraciones: primera aspiración con la cuarta aspiración, no encontrando diferencias estadísticamente significativa (p>0,05) ; luego se compararon la 4ta aspiración con la 7ma aspiración, resultando estadísticamente significativo (p<0,05). Con respecto a la cantidad de ovocitos viables por aspiraciones se obtuvo en promedio 206 ±30 ovocitos y 88 ovocitos no viables, los cuales comparando la primera con la cuarta aspiración arrojan resultados estadísticamente significativos (p< 0,05). En cuanto a calidad de ovocitos los resultados demuestran mayor cantidad de ovocitos GIII, los mismos fueron analizando estadísticamente de la siguiente manera: comparación entre la primera (22,4) y la cuarta aspiración (20,1) de la calidad de ovocitos GI, GII, GIII, arrojando resultados estadísticamente no significativos (p>0,05).

Abstract In order to determine the effect of substituting protein ingredients on production parameters (daily weight gain, feed intake and feed conversion) in confined bulls, bovine animals were selected, grouped into 2 lots in a random and homogeneous manner, composed of nelore-type bulls between 1 and 3 years of age: Treatment 1 (T1) 51 bulls with feed based on corn mockery and Treatment 2 (T2) 51 bulls with feed based on soybean expeller. The initial weighing was carried out at the entrance of the animals, after which two weighings were carried out, one at 45 days and the other at 90 days. At the end of the period, the weights of each group were compared. The results obtained based on the daily weight gain were subjected to the T-Student statistical method, observing significant differences (p<0.05), in favor of T2 in relation to T1. Daily weight gain was 1.47 kg/day at T1, 1.52 kg/day at T2, with daily consumption at T1 being 16.8 kg and 17.4 kg at T2, in terms of feed conversion at T1 it was 6.75 kg and at T2 it was 6.82 kg.

Resumen Con el objetivo de determinar el efecto de la sustitución de ingredientes proteicos sobre parámetros productivos en toros confinados (ganancia diaria de peso, consumo y conversión alimenticia), fueron seleccionados animales de la especie bovina, agrupados en 2 lotes de forma aleatoria y homogénea, compuestos por toros tipo nelore de entre 1 a 3 años de edad: Tratamiento 1 (T1) 51 toros con alimento a base de burlanda de maíz y Tratamiento 2 (T2) 51 toros con alimento a base de expeller de soja. El pesaje inicial se realizó a la entrada de los animales. Posterior a eso se procedió a dos pesajes, uno a los 45 días y otro a los 90 días. Al final del período se realizó la comparación de los pesos de cada grupo. Los resultados obtenidos en base a la ganancia diaria de peso fueron sometidos al método estadístico T-Student, observándose diferencias significativas (p<0,05) a favor del T2 en relación al T1. La ganancia diaria de peso fue en el T1 de 1,47 kg/día y en el T2 1,52 kg/día, siendo el consumo diario en el T1 de 16,8 kg y en el T2 17,4 kg. En cuanto a la conversión alimenticia en el T1 fue de 6,75 kg y en el T2 fue de 6,82 kg.

Con el propósito de evaluar el crecimiento, desarrollo y rendimiento de los clones de papa (Solanum tuberosum L.) 392634-5, 392636-9, 392639-1, 392639-17, 392639-41, 393160-3, 393180-10 393194-1, 393258-16, 393258-44, 393258-49 y la variedad Andinita, en las localidades, Marajabú y Páramo de Cabimbú, estado Trujillo, Venezuela, se condujo ensayos bajo un diseño de bloques al azar con cuatro repeticiones, bajo arreglo factorial 12x2. Se evaluó porte, vigor, altura de planta, número de tallos por planta, rendimiento y las fases del cultivo. Las variables cuantitativas se analizaron con el procesador de datos SAS®.Los clones bajo estudio presentaron un hábito de crecimiento erecto, buen vigor (6-8), adecuada altura, en Marajabú las familias 392639 y 393258 presentaron un rendimiento estadísticamente similar a Andinita y fueron más precoces que la variedad testigo. En el Páramo de Cabimbú los clones 392639-41 y 393258-44 mostraron un rendimiento significativamente superior a la variedad testigo y cumplieron sus etapas de crecimiento y desarrollo en menor tiempo que Andinita. Las características mostradas por estos clones los perfilan como promisorios y serán incluidos en etapas subsiguientes de evaluación y selección.

In order to evaluate the growth, development and yield of potato (Solanum tuberosum L.) clones 392639-1, 363258-44, 393160-3, 393258-16, 393180-10, 392634-5, 392639-41, 392639-17, 392636-9, 393194-1, the 393258-49 and "Andinita" variety, in "Marajabú" and "Páramo de Cabimbú", Trujillo State, Venezuela, an essay was carried out under a randomized blocks design with four replications, in a factorial arrangement 12x2. The growth habit, vigor, plant height, stems number by plant, yield and culture phases were evaluated. The quantitative variables were analyzed with the data processor SAS®. The studied clones showed a habit of turgid growth, good vigor (6-8), suitable height, in "Marajabú" the families 392639 and 393258 showed a statistically similar yield to "Andinita" and showed to be more precocious than the control variety. In "Páramo Cabimbú" the clones 392639-1 and 362634-1 showed a significantly superior yield to the control and fulfilled their growth and development stages in smaller time than "Andinita". The characteristics shown by these clones outline them to be including in subsequent stages of evaluation and selection.

The aim of this study was to prepare light-cured dental composites and to evaluate their physical, chemical and mechanical properties. Experimental composites were prepared from 2, 2 bis [4-(2-hidroxy 3-metacriloxypropoxi) phenyl] propane (Bis-GMA), tetraethyleneglycol dimethacrylate (TEEGDMA), 3-methacryloxypropyl trimethoxysilane (MPS) and a hybrid filler consisting of quartz and colloidal silica particles (Aerosil 90). The initiation system was based on the pair Camphorquinone (CQ) / N, N dimethylaminoethylmethacrylate (DMAEMA). The experimental composites and a commercial dental composite used as reference (Charisma®) were submitted to determinations of depth of cure, water absorption and solubility, compressive and diametral tensile strengths, and elastic modulus, according to the indications of the ISO standards. The experimental resins presented adequate values for most of the analyzed properties, except for compressive strengths. In the Bis-GMA/ MPS/quartz-aerosil composite a better integration between filler and matrix was observed. The Bis-GMA/TEEGDMA/quartz-aerosil composite showed the best performance in regards to depth of cure, solubility in water, diametral tensile strength and elastic modulus. The properties of this composite were better than those of the commercial reference material, except for compressive strength.

From the leaves of Bursera fagaroides var. elongata was isolated luteolin 3'-O-α-L-rhamnopyranoside, from the leaves of B. heteresthes was isolated luteolin 7-O-β-D-glucopyranoside, and myricetin 3'-O-α-L-rhamnopyranoside was isolated from Bursera ariensis, B. biflora, B. bipinnata, B. excelsa, B. hintonii (Mich.) and B. sarukhanii.

De las hojas de Bursera fagaroides var. elongata se aisló el 3'-O-α-L-ramnopiranósido de luteolina, de las hojas de B. heteresthes se obtuvo 7-O-β-D-glucopiranósido de luteolina, y 3-O-α-L-ramnopiranósido de miricetina se aisló de las hojas de la Bursera ariensis, B. biflora, B. bipinnata, B. excelsa, B. hintonii (Mich.) y B. sarukhanii.

Objectives: Circannual variation in morbi-mortality for ischemic heart disease is well-known but there are few data focusing on chronic heart failure (CHF). This report analyzes seasonal variations in CHF hospitalizations and mortality in Vigo, Northwest of Spain. Methods: Data on hospital discharge reports with a diagnosis of CHF (3-digit ICD9 code 428) were obtained from the Clinical Documentation Service at Hospital Meixoeiro (419 beds, population: 167.000 inhabitants 14 years old). Data were divided in three 4-months periods: winter (november-february, years: 1997-98, 98-99 and 99-00), spring (mars-june, years: 97, 98 and 99) and summer (july-october, years: 97, 98 and 99). Hospitalization rates and mortality were also studied at Cardiology, Internal Medicine and Geriatrics (attending to 81% of patients with CHF). Results: A total of 1.472 CHF hospitalizations were registered (52% male, 83% 65 years, mean inhospital stay: 13.8 days). Significatives winter increases were noted in global hospitalizations -4.9% (winter) vs. 3.2 ‰ (summer)and overall medical services admissions -9.3% (winter) vs. 6.2‰ (summer). These increases also were observed at specific medical services (Cardiology: +4.9%, Internal Medicine: +6.5%, Geriatrics: +3.2%). There was not seasonal differences in letality or attributable mortality for CHF. Death in patients with a diagnosis of CHF was 4 times more likely. (OR:3.81; 95% CI: 3.28-4.42). Conclusions: There are a striking increase in winter hospitalizations for CHF. This diagnosis is associated with an excess of inhospital mortality. Preventive and therapeutic measures taking in account this observation are warranted to reduce the burden of this growing problem.

Objetivos: Son conocidas las variaciones estacionales en la morbi-mortalidad de procesos como la cardiopatía isquémica, pero hay escasos datos referentes a la insuficiencia cardiaca crónica (ICC). Este estudio analizó las variaciones estacionales en la hospitalización y muerte por ICC en Vigo. Métodos: El Servicio de Documentación Clínica del Hospital Meixoeiro (419 camas, 167.000 habitantes 14 años) facilitó datos clínicos y estadísticos de las altas con diagnóstico de ICC (Código CIE9: 428). Los datos se dividieron en 3 periodos cuatrimestrales: invernal (noviembre-febrero, años 1997-98, 98-99 y 99-00), primaveral (marzo-junio, años 97, 98 y 99) y veraniego (julio-octubre, años 97, 98 y 99). Estudiamos también tasas de hospitalización y mortalidad en Cardiología, Medicina Interna y Geriatría, que atendieron al 81% de todas las ICC ingresadas. Resultados: Hubo 1472 altas con el diagnóstico de ICC (52% varones, 83% 65 años, estancia media global: 13,8 días). Existió aumento de hospitalizaciones invernales tanto globales -4,9‰ (invierno) vs 3,2‰ (verano)-, como de servicios médicos totales -9,3‰ (invierno) vs 6,2‰, (verano). Este aumento invernal también se observó en servicios específicos: Cardiología: +4,9%, Medicina Interna: +6,5%, Geriatría: +3,2%. No hubo variaciones estacionales en la letalidad o mortalidad atribuible a ICC. El diagnóstico de ICC conllevó un riesgo de muerte 4 veces superior para los pacientes con dicho diagnóstico (OR: 3,81; IC: 3,28-4,42). Conclusiones: El diagnóstico de ICC conlleva un exceso de mortalidad intrahospitalaria. Hubo un significativo aumento de hospitalizaciones invernales por ICC. Aquellas medidas dirigidas al control de este creciente problema deberían tomar en cuenta estas observaciones.

São estudados os resultados de numerosas experiências de adubação da cana-de-açúcar, conduzidas entre 1950 e 1963 em várias localidades do Planalto Paulista, nas quais diversos fosfatos foram comparados, na presença de NK, com superfosfato simples. A resposta média ao super-fosfato simples correspondeu a +21,8 t/ha (+26%) de cana. Atribuindo-se o valor 100 ao efeito dêsse adubo, foram os seguintes os índices de eficiência dos fosfatos que figuraram em seis ou mais experiências: termofosfato, 107; fosfato bicálcico, 105; farinha de ossos degelatinados, 91; fosforita de Olinda, 63; fosfato Alvorada, 61; fosfato de Araxa, 57; bauxita fosforosa, 40. Os autores também estudaram a influência dos tipos de solo, bem como dos níveis de fósforo solúvel e do grau de acidez das áreas utilizadas.

Based on experiments conducted from 1950 up to 1963 on different soil types of the State of São Paulo, the authors studied the efficiency of several phosphorus carriers, for the fertilization of sugar cane, when applied in the presence of NK at the rate of 100 kilograms of total P2O5 per hectare. The areas used were all deficient in phosphorus with pH varying between 4.5 and 6.3. Giving the value 100 to the responses to ordinary superphosphate, the average relative efficiencies of the phosphates that were used in 6 to 14 experiments were the following: thermophosphate, 107; dicalcium phosphate, 105; bone meal, 91; Olinda-phosphate, 63; Alvorada-phospha-te, 61; Araxá-phosphate, 57; phosphorous bauxite, 40. The four latter carriers are natural phosphates from different regions of Brazil. The authors also studied the influence of the soil types, as well as that of the pH and the level of available phosphorus in the soil.

Dando prosseguimento ao estudo da eficiência de diversos fosfatos para a cultura da cana-de-açúcar, neste trabalho são relatadas mais cinco experiências, realizadas entre 1961 e 1963 (três em terra-roxa-misturada, uma em solo massapé-salmourão e uma em solo derivado do arenito Bauru), nas quais foram empregados, na presença de NK, 50. 100 e 150 kg/ha de P2O5 total. Tôdas apresentaram produções satisfatórias e respostas significativas ao fósforo. Em média das cinco experiências e das três doses usadas, foram os seguintes os aumentos porcentuais, na produção de cana-planta, proporcionados pelos fosfatos estudados: termofosfato, 49; fosfato bicálcico, 39; farinha de ossos degelatinados, 38; superfosfato simples, 35; fosfato Alvorada, 28; fosforita de Olinda, 26; fosfato de Araxá, 20; bauxita fosforosa, 10. Houve consideráveis diferenças no comportamento dos fosfatos nas experiências individuais, mas os autores preferem deixar para estudá-las em conjunto com outras conduzidas anterior e posteriormente, quando procurarão associá-las às características dos solos estudados.

Five experiments were conducted in the State of São Paulo to study the efficiency of different sources of phosphorus for the production of sugar cane on three types of soil, using 50, 100 and 150 kilograms of total P2O5 per hectare in the presence of NK. The soil pH varied from 4.8 to 5.6. Phosphorus significantly increased the yields in all of the experiments. As an average of the five experiments and the three rates of application, the per-cent yield increases caused by the studied phosphorus carriers were the following: thermophosphate, 49; dicalcium phosphate, 39; bone meal, 38; ordinary superphosphate, 35; Alvorada-phosphate, 28; Olinda-phosphate, 26; Araxá-phosphate, 20; phosphorous bauxite, 10. The four latter sources are natural phosphates from different regions of Brazil.

Como parte de um programa que vem sendo executado desde 1950, foram conduzidas, em 1959-60, em diferentes localidades do Estado de São Paulo, três experiências para estudar o efeito de diversos fosfatos sôbre a produção de cana-planta, empregando-se, na presença de NK, doses de 50, 100 e 150 kg/ha de P2O5. Nas três experiências, as produções atingiram níveis elevados e o efeito médio do fósforo foi positivo e significativo. Em uma delas, instalada em terra-roxa-misturada, os fosfatos naturais (fosforita de Olinda e fosfato Alvorada) mostraram-se estatisticamente equivalentes aos fosfatos solúveis (superfosfato simples, superfosfato triplo e termofosfato); todavia, nas outras duas, em terra-roxa-legitima e em solo massapê-salmourão, os solúveis superaram significativamente os naturais. As diferenças entre os dois fosfatos naturais foram sempre muito pequenas; entre os solúveis, variaram apreciàvelmente em cada experiência, mas no conjunto seus efeitos foram equivalentes.

Three experiments were conducted in 1959-60 in the State of São Paulo to study the efficiency of different sources of phosphorus for the production of sugar cane, using 50, 100 and 150 kilograms of total P2O5, per hectare in the presence of NK. Phosphorus significantly increased the yields in all of the experiments, in one of them, on «terra-roxa-misturada» type of soil, the natural phosphates (local rock phosphates) were statistically equivalent to the soluble phosphates (standard superphosphate, treble superphosphate and thermophosphate); however, in the other two experiments, on «terra-roxa-legítima» and «massapé-salmourão» soils, the soluble phosphates showed to be significantly better. The differences between the two natural phosphates were always small; among the soluble ones they were appreciable, but not significant.

Em 1961-62 foram conduzidas três experiências de adubação da cana-de-açúcar que comparavam, na presença de NK, superfosfato simples, fosforita de Olinda, fosfato de Araxá e misturas que continham um têrço ou metade da dose de fósforo como superfosfato, sendo o resto fornecido por um dos fosfatos naturais.Êsses adubos foram comparados, nas doses de 50, 100 e 150 kg/ha de P2O3 total, em solo do arenito Bauru, terra-roxa-misturada e solo massapê-salmourão. As produções de cana-planta alcançaram níveis satisfatórios e o efeito médio do fósforo foi significativo nas três experiências. Em média destra e das três doses usadas, os aumentos de produção obtidos foram: com superfosfato, 25%; com os fosfatss naturais, 17%; com as misturas tendo um têrço ou metade do fósforo como superfosfato, 22 e 29%, respectivamente. Não houve, pràticamente, diferença entre os dois fosfatos naturais. Conquanto o efeito dêstes, quando empregados sòzinhos, tenha sido relativamente pequeno, o das misturas em que figuraram com metade da dose de fósforo foi até um pouco superior ao do superfosfato, indicando a possibilidade de reduzir-se o custo da adubação fosfatada da cana-de-açúcar.

In the three experiments reported ordinary superphosphate was compared, in the presence of NK, with Olinda and Araxá phosphates (ground natural phosphates), and mixtures containing 1/3 or 1/2 of the phosphorus dosis as superphosphate, the remaining being supplied by one of the natural phosphates. These fertilizers were compared at the doses of 50, 100 and 150 kilograms of total P2O5 per hectare, on three different soil types of the State of São Paulo with pH around 5.20. Satisfactory yields and significant responses to phosphorus were obtained in the three experiments. In the average of these and of the three rates of application, the yield increases were the following: with superphosphate, 25%; with the natural phosphates, 17%; with the mixtures containing two thirds or half the phosphorus doses as natural phosphates, 22 and 29%, respectively. Practically, there was no difference between Olinda and Araxá phosphate.

Com os trabalhos de melhoramento da cana-de-açúcar, realizados em 1947, 1948 e 1949, obtiveram-se numerosos «seedlings» muito promissores, que foram estudados em ensaios de competição com as melhores variedades existentes. Foram realizadas duas séries de experiências, em terras de várias usinas do Estado de São Paulo, tôdas em solo de terra-roxa-misturada. A primeira série foi plantada em 1954, usando-se na comparação a variedade Co. 290. Estas experiências foram encerradas após o segundo corte, em 1956. Na segunda série, iniciada em 1957, aproveitaram-se os «seedlings» que mais se destacaram na primeira. Nesse estudo, utilizou-se um delineamento em lattice balanceado 5x5 com 6 repetições. Como testemunhas, foram utilizadas as variedades CB 41/76, Co. 419 e CB 40/69. Em cada experiência desta série foram feitos três cortes: cana-planta, soca e ressoca. Os resultados mostraram produções muito baixas para a variedade Co. 419, bem inferiores às da CB 41/76 e 40/69. Os «seedlings» de números 49/131, 48/65 e 47/31 apresentaram, em geral, produções superiores às das testemunhas. O «seedling» 47/13, embora com produções nem sempre superiores às das duas CB testemunhas, apresentou alta riqueza em açúcar. O «seedling» 49/3, por sua vez, com produção de cana. das melhores, não satisfez quanto à riqueza em açúcar. Os demais «ssedlings» estudados não apresentaram maior interêsse. Foram considerados como novas variedades, recebendo prefixo IAC, os «seedlings»: 47/13, 47/31, 48/65, 49/3 e 49/131.

As a result of breeding work carried out by the Sugar Cane Department along the years 1947, 1948 and 1949, quite a lot of seedlings had been obtained, after several selections. This considerable number of seedlings was then studied with the purpose of determining which of them could be qualified so as to be considered as new varieties. To this effect two series of experiments were conducted at the factories Santa Elisa, Tamoio, Ester and Pôrto Feliz, all of them on soil of the type «terra-roxa-misturada». The first series of experiments was established in 1954 having Co. 290 as control, a variety which was the most planted by then. After the second harvest in 1956, these experiments were brought to an end, since Co. 290 showed then a rather severe decrease in production so that it could no longer meet the conditions for which it had been used initially. Due to this, a second series had to be started where just those seedlings were used that had outstanding qualities in the first series. Thus, they were planted in 1957 at the same localities as the first series of experiments, but this time a design was used of a balanced lattice 5x5 with 6 replications. As controls were used the varieties CB 41/76, Co. 419 and CB 40/69 which were then the most recommended for the State of São Paulo. For each experiment three harvests were made, plant cane, first and second ratoons. From the results obtained it was found that the variety Co. 419 gave small yields pretty lower than those of CB 41/76 and CB 40/69; the seedlings known as 49/131, 48/65 and 47/31 showed in general rather high yields in comparison to the controls; S 47/13, in spite of its productions not being in all cases higher than those of the two CB controls, showed a high content in sugar, whereas on the other hand, S 49/3, although with the best productions in tonnage of cane, didn not satisfay with regard to its sugar content. The other seedlings under study did not deserve any interest. As new varieties just the following seedlings were considered: n.º 47/13, 47/31, 48/65, 49/3 and 49/131, receiving the prefix IAC.

Em 1957-58 foram conduzidas, em fazendas da Usina Itaiquara, com sede no Município de Tapiratiba, São Paulo, 18 experiências fatoriais 3³ para N, P e K, usando-se 0, 80, 160 kg/ha de N e K2O, como sulfato de amônio e cloreto de potássio, e 0, 90, 180 kg/ha de P2O5, como superfosfato simples. As áreas utilizadas, tôdas do grande tipo de solo massapê-salmourão, haviam sido cultivadas durante períodos muito diferentes, variando também o número de vêzes que foram adubadas com uma fórmula constituída quase exclusivamente de fósforo. O ano agrícola 1957-58 foi favorável à cultura da cana. O efeito do fósforo só foi significativo em seis, das 18 experiências. Em média, destas e das duas doses, êle correspondeu a +8,3 t/ha, mas variou muito nas experiências individuais. Tendo alcançado +40,3 e +43,1 t/ha nas duas localizadas em áreas adubadas uma vez nas culturas anteriores, oscilou entre -3,5 e +12,5 t/ha nas 16 conduzidas em áreas que já haviam recebido duas a cinco adubações. Entretanto, o efeito do potássio só não obteve significância em uma experiência e as respostas médias às suas doses 1 e 2 corresponderam, respectivamente, a +12,9 e + 23,5 t/ha. Em uma experiência a dose 2 aumentou a produção de apenas 4,3 t/ha, mas em sete provocou aumentos de 11,3 a 18,5 e, nas outras dez, de 20,0 a 54,6 t/ha. O efeito do nitrogênio, que correspondeu a +6,8 t/ha na média geral, só foi significativo em seis experiências. Mesmo na presença do potássio, que a tornou maior, a resposta à dose 2, +9,8 t/ha, não foi satisfatória. Em média das 18 experiências, a produção de cana, que foi de 90,6 t/ha no tratamento sem adubo e passou a 101,4 t/ha no adubado exclusivamente com a dose 1 de fósforo (adubação semelhante à empregada pela usina), elevou-se a 135,8 t/ha no que recebeu as doses maiores dos três elementos. A grande reação ao potássio é atribuída principalmente ao fato de, na sua maioria, as áreas estudadas terem sido cultivadas por longo tempo e recebido adubações quase exclusivamente fosfatadas. Essas adubações explicam, também, o pequeno efeito do fósforo na maior parte das experiências. É de estranhar que, em tais condições, as respostas ao nitrogênio não tenham sido mais pronunciadas.

Eighteen 3³ factorial experiments using 0, 80, 160 kg/ha (kilograms to the hectare) of N and K2O, and 0, 90, 180 kg/ha of P2O5 were conducted in 1957-58 in farms belonging to the sugar factory Itaiquara, located at Tapinitiba, State of São Paulo. The areas studied, all of the "massapê-salmourão" type of soil, had been cropped during different periods and, when fertilized, received a mixture containing almost exclusively phosphorus. The effect of phosphorus was significant only in six of the 18 experiments. The average responses to it readied +40.3 and +43.1 t/ha (metric tons of cane per hectare) in two trials located on areas which had received one phosphorus application in the previous crops, but varied between -3.5 and +12.5 t/ha in the 16 areas that had received two to five such applications. Contrarily to that of phosphorus, the effect of potassium was significant in all but one trial and the average responses to the rates of 80 and 160 kg/ha of K2O corresponded to +12.9 and +23.5 t/ha, respectively. The effect of nitrogen was generally unsatisfactory and significant only in six experiments. Even in the presence of potassium, which increased the need for it, the average response to its larger dose was +9.8 t/ha. While the average yield was 90.6 t/ha in the unfertilized plots and 101.4 t/ha in those exclusively fertilized with 90 kg/ha of P2O5, (a treatment similar to that previously used by the farmer), that of the plots which received the larger doses of the three elements reached 135.8 t/ha. Most of the areas studied were cropped for long time and fertilized almost exclusively with phosphorus. These facts explain the high responses to potassium and the small effect of phosphorus in the greatest part of the trials. The information available are not sufficient to explain why, in such conditions, the responses to nitrogen were not higher.