ABSTRACT The objective was to evaluate the influence of calving and postpartum characteristics, measured in different genetic predominance, on the postpartum rebreeding. Were evaluated 437 partum from cows that received feeding management consisting of a forage base of the native field and the mating season consisted of 90 days. The measurements were used from the data base (age of cow, genetic predominance, body weight, body condition score and date of calving) of the cows in the partum and postpartum period. The variables were submitted to analysis of multiple variances, multiple regression, correlation and cluster. Already the groups formed by cluster analysis were submitted to analysis of variance and F test and the means, compared by Student’s t-test, α=0.05 probability. The increase in the mean at 0.14 points in the body condition score at calving and the occurrence of calving 9 days earlier at the calving season gives the Charolais genetically predominant cows repeat calves. The Nellore genetic predominance when they calved with similar body condition score (2.32 points) and showed a negative body weight gain at weaning (-3.0 kg and -2.1 kg) showed different behaviors, where they did not repeat the offspring, when they calved and weaned with smaller body weight.

The present paper establishes criteria for the management and the operation of the irrigation process in controlled atmospheres (green houses); as well as the use of combined fertilization and the criteria to be taken for a proper management of the irrigation system so that it meets crop water requirements according to the development phase under the principle of conservation of natural resources and environmental preservation.

En el presente trabajo se establecen criterios para el manejo y la operación del riego en ambientes controlados (casas de cultivo), así como el uso de la fertilización combinada y los criterios a seguir para realizar un manejo adecuado del sistema de riego de forma tal que satisfaga las necesidades hídricas del cultivo de acuerdo a la fase de desarrollo, bajo el principio de la conservación de los recursos naturales y la preservación del medio ambiente.

We use the self-consistent harmonic approximation (SCHA) to study static properties of the two-dimensional quantum Heisenberg model with easy-axis anisotropy. We calculate the critical temperature as a function of the spin value, and compare with classical results. Specifically, we compare how the ratio of critical temperatures varies as a function of the spin S in the quantum and classical cases, for afixed anisotropy parameter. We see that, for values of spin near 5/2, the classical result approximates to the quantum results and the classical calculation is justified. We have also studied the behavior of the magnetization for very small anisotropies. We have shown that our magnetization curves do not present a plateau in the limit of very small anisotropies, as predicted by the real-space renormalization-group calculations.

Os efeitos de reguladores vegetais do grupo das giberelinas e citocininas, bem como do nitrato de potássio, foram estudados no crescimento e desenvolvimento do porta-enxerto de limoeiro `Cravo' (Citrus limonia Osbeck). As sementes foram extraídas de frutos maduros, lavadas, secas à sombra e armazenadas em câmara fria (4 - 5oC) durante sessenta dias, até o mês de maio/1993, quando foram semeadas nos canteiros de semeadura. As pulverizações com os fitorreguladores foram realizadas no viveiro e tiveram início com as plantas aos 8 meses de idade, contados a partir da semeadura, sendo efetuadas um total de 4 pulverizações, realizadas a intervalos quinzenais. Os tratamentos corresponderam a: 25, 50 e 75 ppm de GA3; 25, 50 e 75 ppm de GA4+GA7+fenilmetil-aminopurina; 20 ppm de fenilmetilpiranil-aminopurina; 0,2% de KNO3 e testemunha (sem pulverização). Os resultados obtidos permitiram concluir que as pulverizações com os reguladores vegetais e com o nitrato de potássio, realizadas no período de janeiro a março (verão), não tiveram efeito na diminuição do tempo de formação das plantas jovens de limoeiro `Cravo', tendo inclusive, o tratamento com KNO3 0,2%, exercido efeito depressivo no desenvolvimento das mesmas.

The effects of gibberellins, cytokinins and potassium nitrate on the development of `Rangpur'lime (Citrus limonia Osbeck) rootstocks were studied. Seeds from ripe fruits were washed, dried and stored at 4 - 5o C for 60 days. They were planted in nursery plots in May/1993 and when the seedlings had 10 - 20 cm height, they were transplanted to a second nursery stage. The seedlings were sprayed at 15-day intervals, with plant regulators and potassium nitrate, after reaching the age of 8 months. From January to March/1993, the seedlings were sprayed with: 25, 50 and 75 ppm of GA3; 25, 50 and 75 ppm of GA4+7 + phenylmethyl-aminepurine; 20 ppm of phenylmethylpyranil-aminepurine; 0.2% of KNO3. The seedlings planted in May/1993 did not reach earlier suitable size for budding when compared to the control. The treatments with KNO3 0.2% showed a tendency to inhibit the seedling growth.

Estudou-se os efeitos de auxilias exógenas e ácido bórico, no enraizamento de estacas de lichia (Litchi chinensis Sonn.). As estacas foram uniformizadas, com 25 cm de comprimento e 4 folhas cortadas pela metade. Cerca de 2,5 cm da base das mesmas foi mergulhado nos tratamentos: H2O; Boro 150 µg/ml; IBA 5.000 ppm, IBA 2.000 ppm; IBA 5.000 ppm + Boro 150 µg/ml; IBA 2.000 ppm + Boro 150 µg/ml; NAA 3.000 ppm; NAA 1.500 ppm; NAA 3.000 ppm + Boro 150 µg/ml; NAA 1.500 ppm + Boro 150 µ/g/ml. A estaquia foi realizada no mês de setembro (Hemisfério sul), sendo que as estacas foram colocadas em bandejas de isopor, tendo como substrato vermiculita e mantidas sob nebulização intermitente. Os resultados obtidos permitiram concluir que o IBA 5.000 ppm por 1 minuto foi o tratamento mais efetivo, proporcionando 83,33% de estacas enraizadas em 120 dias, enquanto o tratamento testemunha (H2O), apresentou somente 16,67% de estacas enraizadas.

The effects of exogen auxins and boric add were studied on lychee (Litchi chinensis Sonn.) cuttings. Cuttings were standardized to twenty-five cm length, with four leaves, cut in half. The bases of the cuttings were dipped of 2,5 cm in water solutions, resulting in the following treatments: H2O; Boron 150 µg/ml; IBA 5,000 ppm; IBA 2,000 ppm; IBA 5,000 ppm plus boron 150 µg/ml; IBA 2,000 ppm plus boron 150 µg/ml; NAA 3,000 ppm; NAA 1,500 ppm; NAA 3,000 ppm plus boron 150 µg/ml; NAA 1,500 ppm plus boron 150 µg/ml. Cutting was performed in September (southern hemisphere) and the cuttings were place in styrofoam trays, using vermiculite as substratum and kept under intermittent mist It was concluded that 5,000 ppm IBA for one minute was the best treatment to improve rooting (83,33%), while the control (H2O) showed only 16,67% of rooted cuttings.

Foram avaliados os efeitos de fitorreguladores (giberelinas e citocininas) e nitrato de potássio (KNO3), na germinação de sementes e na promoção do crescimento de "seedlings" do porta-enxerto 'Nasnaran' (Citrus amblycarpa Ochese). Realizou-se primeiramente o experimento em germinador, contendo papel de filtro umedecido com água destilada e gerbox, como meio para a germinação das sementes. Os tratamentos foram realizados mediante imersão das sementes, em soluções preparadas com os fítorreguladores e KNO3, durante 24 horas. Através dos resultados obtidos, concluiu-se que o tratamento com 100 mg/1 de GA4 + GA7 + fenilmetilaminopurina, apresentou a maior porcentagem de germinação (88%), num tempo médio de 21 dias. Tomando como base o resultado do germinador, sementes de Citrus amblycarpa foram semeadas em canteiros e quando as plantas atingiram a altura de 6,0 cm receberam 2 pulverizações com 0; 50; 100 e 150 mg/1 de GA4 + GA7 + fenilmetilami-nopurina, com intervalo de 21 dias. Avaliou-se a matéria seca total, caule e folhas, área foliar e altura das plantas, sendo que a análise desses parâmetros mostrou que o GA4 + GA7 + fenilmetUaminopurina na concentração de 50 mg/1 foi o tratamento que apresentou os melhores resultados.

The effects of growth regulators (gibberellins and cytokmins) and potassium nitrate were evaluated for Citrus amblycarpa seed germination and rootstock growth. First an experiment was performed in a germinator, using as a medium for seed germination filter paper wetted with distiled water. Seeds were treated with growth regulators and potassium nitrate during 24 hours. The results obtained indicate that the treatment of 100 mg/1 of GA4 + GA7 + phenylmethylaminepurine was the best, with a percentage of germination of 88% at 21 days. Based on the results obtained in the germinator, seeds of Citrus amblycarpa were seeded in soil and when the seedlings were 6 cm high they were sprayed with 50 mg/1 of GA4 + GA7 + phenylmethylaminepurine; 100 mg/1 of GA4 + GA7 + phenylmethylaminepurine and 150 mg/1 of GA4 + GA7 + phenylmethylaminepurine. Dry weights of leaves and stems, leaf area and height of plants were evaluated. The analysis of these parameters showed that the GA4 + GA7 + phenylmethylaminepurine at 50 mg/1 was the best treatment.

Foram estudados os efeitos de substâncias reguladoras de crescimento, bem como do nitrato de potássio (KNO3), na germinação de sementes do limão 'volkameriano' (Citrus volkameriana Pasq.). O experimento foi realizado em germinador, contendo papel de filtro umedecido com água destilada e gerbox, como meio para a germinação das sementes. Estas foram retiradas de frutas maduras, lavadas, secas à sombra e armazenadas durante 101 dias em câmara fria. Logo após, foram tratadas com os fitorreguladores e o KNO3 por 24 horas, conforme os tratamentos: H2O; 50 mg/l de GA3; 250 mg/l de GA3; 50 mg/l de GA4 + GA7 + fenilmetilaminopurina; 100 mg/l de GA4 + GA7 + fenilmetilaminopurina; 20 mg/lde fenilmetilaminopurina; 40 mg/lde fenilmetilaminopurina e 0,2% de KNO3. As avaliações foram realizadas depois de 15 dias da semeadura, sendo o intervalo de 2 dias. Através da análise estatística dos resultados obtidos, foi possível concluir que no tratamento com 50 mg/lde GA4 + GA7 + fenilmetilaminopurina houve a maior porcentagem de germinação (89,00%) de sementes, num menor tempo médio (22,29 dias).

The purpose of this research was to study the effects of growth regulators and potassium nitrate on 'volkameriana' lemon seed germination. The medium for seed germination was filter paper with distilled water. The seeds were removed from ripe fruits, washed, dried and stored at 4-5°C. After this the seeds were treated with growth regulators and potassium nitrate during 24 hours. The treatments were H2O; 50 mg/lof GA3; 250 mg/lof GA3; 50 mg/lof GA4 + GA7 + phenylmethylaminepurine; 100 mg/l of GA4 + GA7 + phenylmethyla-minepurine; 20 mg/lof phenylmethylaminepurine; 40 mg/lof phenylmethylaminepurine and 0,2% of KNO3. The evaluations were performed every two days, starting 15 days after seeding. The moisture with GA4 + GA7 plus phenylmethylaminepurine at 50 mg/lproved to be the most beneficial in enhancing seed germination.

Estudaram-se as interações entre os ácidos indol-butírico, alfa-naftaleno-acético e bórico no desenvolvimento de calos e na sobrevivência das estacas de lichieira (Litchi chinensis Sonn.). As estacas apresentavam 25 cm de comprimento e 4 folhas cortadas pela metade, sendo retiradas em duas épocas diferentes (janeiro e abril) e colocadas para enraizar em bandejas de isopor, tendo como substrato vermiculita e em condições de câmara de nebulização. Foi feita imersão de 2,5 cm da base das estacas, em soluções aquosas por l minuto. Os tratamentos utilizados corresponderam a 5.000 e 2.000 ppm de IBA; 3.000 e 1.500 ppra de NAA; 150 microgramas/ml de H3BO3; IBA 5.000 e 2.000 ppm + H3BO(3)150 microgramas/ml; NAA 3.000 e 1.500 ppm + H3BO3 150 microgramas/ml e H2O. Avaliou-se a formação de calos e a sobrevivência das estacas após 120 dias do plantio. Através dos resultados obtidos, foi possível concluir que dos tratamentos utilizados, nenhum foi efetivo na formação de raízes, havendo somente a formação de calos. A melhor época para a retirada de estacas correspondeu ao mês de abril.

Interactions between indolebutyric, naphtalen acetic and boric acids were studied on "callus" development and survival in lychee (Litchi chinensis Sonn.) cuttings. The cuttings were twenty five cm long with four leaves cut in half and taken in two different periods (January and April) Styrofoam trays, with vermiculite as substratum kept under intermittent mist were used as rooting media. Cuttings were imersed up to 2.5 cm from the base in water solutions, for one minute. The treatments were: 5,000 and 2,000 ppm of IBA; 3,000 and 1,500 ppm of NAA; 150 micrograms/ml H3BO3; IBA 5,000 and 2,000 ppm plus H3BO3 150 micrograms/ml; NAA 3,000 and 1,500 ppm plus boron 150 micrograms/ml and II2O. "Callus" formation and cutting survival were evaluated 120 days after planting. It was concluded that no treatments were effective on root formation, however, "callus" formation was observed. The best period for taking the cuttings was April.

Estudaram-se as interações entre os ácidos indol-butírico, alfa-naftaleno-acético e bórico no desenvolvimento de raízes em estacas de porta-enxertos de videira (Vitis vinifera L.). As estacas tinham aproximadamente 25 cm de comprimento e, necessariamente, 2 gemas, sendo obtidas em três épocas distintas (janeiro, abril e julho) e colocadas para enraizar em bandejas de isopor, tendo vermiculita como substrato, e mantidas sob nebulização. O tratamento constou da imersão de 2,5 cm da base das estacas em soluções, por um tempo de imersão de 1 minuto. Os tratamentos utilizados corresponderam a: 1 .000; 2.000 e 5.000 ppm de IBA; 1.500 e 3.000 ppm de NAA; 150 microgramas/ml de H3BO3; IBA 1.000; 2.000 e 5.000 + H3BO3 150 microgramas/ml e H2O. Avaliaram-se a porcentagem de enraizamento, o número médio de raízes formadas por estaca e o comprimento médio das raízes (mm) aos 90 dias após a instalação, no mês de julho. O IBA 2.000 ppm propiciou o enraizamento em 88,87% das estacas, contudo não diferiu estatisticamente da testemunha (H2O-61,10%). A melhor época de coleta de estaca para o enraizamento foi o mês de julho (inverno).

The effects of indolebutyric, naphtalen acetic and boric acids were studied on rooting of grape rootstock cuttings. The cuttings were 25 cm long with two buds and were taken in three different times (January, April and July). Rooting was carried out in styrofoam trays with vermiculite as substratum and under intermittent mist. Cuttings were imersed up to 2.5 cm from the base in solutions for one minute. The treatments were: 1,000; 2,000 and 5,000 ppm of IBA; 1,500 and 3,000 ppm of NAA; 150 micrograms/ml H3BO3; IBA 1,000; 2,000 and 5,000 ppm plus H3BO(3)150 niicrograins/ml and H2O. Rooting percentage, average number of roots per cutting and average length of roots (mm) were evaluated 90 days after planting, in July. IBA at 2,000 ppm was the best treatment with 88.8% of rooted cuttings. The best time for rooting was July (winter).