Mite fauna (Acari) associated with apple orchards (Malus domestica) and spontaneous vegetation as reservoir for predatory mites / Acarofauna (Acari) associada a pomares de maçã (Malus domestica) e vegetação espontânea como reservatório de ácaros predadores

Abstract The aim of this study was to recognize the mite fauna associated with apple orchards in southern Brazil and present a dichotomous key of the species sampled and those already reported in apple trees in southern Brazil. The studies were carried out in the 2020/2021 harvest in seven apple orchards of the Eva, Fuji and Gala cultivars located in the municipalities of Muitos Capões, Antônio Prado (Rio Grande do Sul state) and São Joaquim (Santa Catarina state). The orchards were divided into quadrants and sampling was carried out monthly. In each orchard, 40 plants were sampled, with three leaves of each plant collected in apical, median and basal regions of a median branch. In addition, monthly five species of spontaneous plants per orchard were sampled. A total of 8,425 mites were found, with the greatest abundance in Antônio Prado (50%), followed by Muitos Capões (35.5%) and São Joaquim (14.5%). The specimens found belong to 29 families, 64 genera and 99 species, in addition to mites of the order Oribatida. The greatest diversity was found in spontaneous vegetation (59 species), being 19 exclusives to apple trees and 21 species common to apple trees and spontaneous vegetation. Phytoseiidae was the family that presented the greatest richness, with 16 species, of which seven were common in apple trees and spontaneous plants. The most abundant species was Aculus schlechtendali Nalepa (Eriophyidae) (39.5%), followed by Panonychus ulmi (Koch) (Tetranychidae) (14.6%), Polyphagotarsonemus latus (Banks) (Tarsonemidae) (9.4%) and Neoseiulus californicus (McGregor) (Phytoseiidae) (7.4%). These results suggest that the mite fauna present in apple orchards in different landscapes and management are distinct, with a greater diversity of phytoseiid mites present in organic areas. Therefore, to maintain a greater diversity of predatory mites in these orchards, organic management seems to be the most appropriate. Furthermore, the high acarine diversity found in spontaneous vegetation demonstrates the importance of maintaining these plants in orchards that serve as refuges and reservoirs, favoring the permanence of natural enemies in these environments.

Resumo O objetivo deste estudo foi reconhecer a acarofauna associada a pomares de macieira no sul do Brasil e apresentar uma chave dicotômica das espécies amostradas e daquelas já relatadas em macieiras no sul do Brasil. Os estudos foram realizados na safra 2020/2021 em sete pomares de macieiras das cultivares Eva, Fuji e Gala localizados nos municípios de Muitos Capões, Antônio Prado (RS) e São Joaquim (SC). Os pomares foram divididos em quadrantes e a amostragem foi realizada mensalmente. Em cada pomar foram amostradas 40 plantas, sendo três folhas de cada planta coletadas nas regiões apical, mediana e basal de um ramo mediano. Além disso, mensalmente foram amostradas cinco espécies de vegetação espontânea por pomar. Foram encontrados 8.425 ácaros, com maior abundância em Antônio Prado (50%), seguido por Muitos Capões (35,5%) e São Joaquim (14,5%). Os exemplares encontrados pertencem a 29 famílias, 64 gêneros e 99 espécies, além de ácaros da ordem Oribatida. A maior abundância foi encontrada em vegetação espontânea (59 espécies), sendo 19 exclusivas de macieiras e 21 espécies comuns a macieiras e vegetação espontânea. Phytoseiidae foi a família que apresentou maior riqueza, com 16 espécies, das quais sete eram comuns em macieiras e vegetação espontânea. A espécie mais abundante foi Aculus schlechtendali Nalepa (Eriophyidae) (39,5%), seguida por Panonychus ulmi (Koch) (Tetranychidae) (14,6%), Polyphagotarsonemus latus (Banks) (Tarsonemidae) (9,4%) e Neoseiulus californicus (McGregor) (Phytoseiidae) (7,4%). Esses resultados sugerem que a acarofauna presente em pomares de macieira em diferentes paisagens e manejos são distintas, com maior diversidade de ácaros fitoseídeos presentes em áreas orgânicas. Portanto, para manter uma maior diversidade de ácaros predadores nesses pomares, o manejo orgânico parece ser o mais adequado. Além disso, a elevada diversidade de ácaros encontrada na vegetação espontânea demonstra a importância da manutenção destas plantas em pomares que servem como refúgios e reservatórios, favorecendo a permanência de inimigos naturais nestes ambientes.

Diel and seasonal variations in the thermal biology of San Cristobal Lava Lizards (Microlophus bivittatus).

Thermal biology, and therefore energy acquisition and survival, of ectotherms can be affected by diel and seasonal patterns of environmental temperatures. Galápagos Lava Lizards live in seasonal environments that are characterized by a warm and wet period when reproductive activity is maximal, and cooler and drier period. With the use of radiotelemetric techniques to record lizard surface temperatures (Ts), we studied the thermal ecology of the San Cristóbal Lava Lizard (Microlophus bivittatus) during both the warm and cool seasons over two years. During the diel activity period and when operative temperatures exceeded Tset-min, at least on rock faces without canopy, 52% or less of the Ts observations fell within the laboratory-determined Tset range (36-40 °C). Therefore, lizards may have avoided very warm midday temperatures in shaded microhabitats and the lag times in changes in Ts values occurred as operative temperatures rose rapidly during late morning warming phase. Lizards effectively thermoregulated during a year with moderate warm season temperatures and during a cool season that was unseasonably warm. In contrast, lizards less effectively thermoregulated during the warmest and coolest years of the study. We did not detect intersexual differences in thermoregulation although males may thermoregulate less effectively than do females during the cool season although we were unable to detect significant differences using our nonparametric statistical techniques.

Transcription profiling of the chilling requirement for bud break in apples: a putative role for FLC-like genes.

Apple production depends on the fulfilment of a chilling requirement for bud dormancy release. Insufficient winter chilling results in irregular and suboptimal bud break in the spring, with negative impacts on apple yield. Trees from apple cultivars with contrasting chilling requirements for bud break were used to investigate the expression of the entire set of apple genes in response to chilling accumulation in the field and controlled conditions. Total RNA was analysed on the AryANE v.1.0 oligonucleotide microarray chip representing 57,000 apple genes. The data were tested for functional enrichment, and differential expression was confirmed by real-time PCR. The largest number of differentially expressed genes was found in samples treated with cold temperatures. Cold exposure mostly repressed expression of transcripts related to photosynthesis, and long-term cold exposure repressed flavonoid biosynthesis genes. Among the differentially expressed selected candidates, we identified genes whose annotations were related to the circadian clock, hormonal signalling, regulation of growth, and flower development. Two genes, annotated as FLOWERING LOCUS C-like and MADS AFFECTING FLOWERING, showed strong differential expression in several comparisons. One of these two genes was upregulated in most comparisons involving dormancy release, and this gene's chromosomal position co-localized with the confidence interval of a major quantitative trait locus for the timing of bud break. These results indicate that photosynthesis and auxin transport are major regulatory nodes of apple dormancy and unveil strong candidates for the control of bud dormancy.

Factors associated with degree of atopy in Latino children in a nationwide pediatric sample: the Genes-environments and Admixture in Latino Asthmatics (GALA II) study.

BACKGROUND: Atopy varies by ethnicity, even within Latino groups. This variation might be due to environmental, sociocultural, or genetic factors. OBJECTIVE: We sought to examine risk factors for atopy within a nationwide study of US Latino children with and without asthma. METHODS: Aeroallergen skin test responses were analyzed in 1830 US Latino subjects. Key determinants of atopy included country/region of origin, generation in the United States, acculturation, genetic ancestry, and site to which subjects migrated. Serial multivariate zero-inflated negative binomial regressions stratified by asthma status examined the association of each key determinant variable with the number of positive skin test responses. In addition, the independent effect of each key variable was determined by including all key variables in the final models. RESULTS: In baseline analyses African ancestry was associated with 3 times (95% CI, 1.62-5.57) as many positive skin test responses in asthmatic participants and 3.26 times (95% CI, 1.02-10.39) as many positive skin test responses in control participants. Generation and recruitment site were also associated with atopy in crude models. In final models adjusted for key variables, asthmatic patients of Puerto Rican (exp[ß] [95% CI], 1.31 [1.02-1.69]) and mixed (exp[ß] [95% CI], 1.27 [1.03-1.56]) ethnicity had a greater probability of positive skin test responses compared with Mexican asthmatic patients. Ancestry associations were abrogated by recruitment site but not region of origin. CONCLUSIONS: Puerto Rican ethnicity and mixed origin were associated with degree of atopy within US Latino children with asthma. African ancestry was not associated with degree of atopy after adjusting for recruitment site. Local environment variation, represented by site, was associated with degree of sensitization.

Complement dependent cytotoxicity activity of therapeutic antibody fragments is acquired by immunogenic glycan coupling

Oligosaccharides are implicated in the development of the immune response notably in complement activation. Anti-tumoural immunotherapy by monoclonal antibodies (mAbs) offers some advantages to chemotherapy including cell targeting but some of them are inefficient to generate cytotoxicity dependent complement (CDC) known to be important in the antibody’s efficacy. The aim of this study is to give a CDC activity of mAb by linkage of a complement activating oligosaccharide to this antibody via a hetero-bifunctional linker allowing control of the conjugation reaction. We worked on non Hodgkin Burkitt’s lymphoma as cancer source, Fab fragments of rituximab devoid of complement activity as mAb and the trisaccharide Gal alpha(1→3)Gal beta(1→4)GlcNAc as immunogenic glycan. The bioconjugate Fab-Gal was characterized by biochemical methods and we demonstrated that the α-Gal epitope was recognized by seric immunoglobulins. After checking the recognition capacity of the Fab-Gal conjugate for the CD20 epitope, in vitro assays were performed to evaluate the activation of the complement cascade by the Fab-Gal conjugate. The effect of this bioconjugate was confirmed by the evaluation of the proliferation response of Burkitt’s cell line. The relative facility realization of this strategy represents new approaches to increase activities of mAbs.

Variações do conteúdo de glucose, frutose e sorbitol em gemas e ramos de macieira durante a dormência

This research was aimed at evaluating the variations of glucose, frutose and sorbitol content in one year old buds and stems of apple trees during the dormancy period. The stems of cv. Imperial Gala were collected in Porto Amazonas, Parana State, Brazil, at intervals of 21 days from April to August (April 19th, May 10th, May 31st, June 21st, July 12th, August 2nd and August 23rd) and were treated or not with 1,440 hours of chill (4 to 7°C). The carbohydrates were analysed in buds and stem tissues close to buds by high performance liquid chromatography (HPLC). There was an increase of glucose, frutose and sorbitol content in apple tree buds during the dormancy. An increase of glucose and frutose content in stems occured until August 2nd followed by a significative reduction, while the sorbitol content decreased until June 21st followed by an increase until August 31st. The chill treatment during the dormancy period modified the variations of carbohydrate contents in buds and stems of apple tree.

O objetivo deste trabalho foi determinar as variações do conteúdo de glucose, frutose e sorbitol em gemas e ramos de um ano de macieira durante o período de dormência. Os ramos da cultivar "Imperial Gala" foram coletados em Porto Amazonas-PR, em intervalos de 21 dias, de abril a agosto (19/04, 10/05, 31/05, 21/06, 12/07, 02/08 e 23/08), e receberam ou não tratamento com frio suplementar de 1.440 horas à temperatura de 4 a 7°C. As análises dos carboidratos foram realizadas em gemas e porções de ramos adjacentes às primeiras por cromatografia líquida de alta eficiência (HPLC). Ocorreu um acúmulo de glucose, frutose e sorbitol nas gemas de macieira durante a dormência. O acúmulo de glucose e frutose nos ramos aconteceu até o início de agosto quando, em seguida, houve redução, enquanto o sorbitol decresceu até junho e, em seguida, elevou-se até o final de agosto. O tratamento com frio ao longo da dormência modificou as variações dos conteúdos de carboidratos nas gemas e ramos de macieira.

Dinâmica do conteúdo de monossacarídeos em gemas e ramos de dois anos de macieira durante a endodormência

The objective of this work was to evaluate the variation of glucose, fructose and sorbitol content in two year old buds and stems of apple trees during the dormancy period. Stems of cv. Imperial Gala were collected in Porto Amazonas, Parana State, Brazil, a region of low chill occurence, at intervals of 21 days from April to August and were treated or not with 1,440 hours of chill (4 to 7°C). The monosaccharides were analysed in buds and stem tissues close to buds by high performance liquid chromatography (HPLC). There was an increase of glucose and fructose content in buds from April to August and it was stimulated by the chill treatment. The glucose and fructose content in stems increased from April to August 2nd followed by a reduction in August 23rd and the chill treatment advanced this dynamics. The sorbitol content in buds and stems of apple tree oscillated from April to August and its dynamics was modified by the chill treatment.

O objetivo do trabalho foi determinar as variações do conteúdo de glucose, frutose e sorbitol em gemas e ramos de dois anos de macieira que receberam ou não frio suplementar durante o período de dormência. Os ramos da cultivar Imperial Gala foram coletados em Porto Amazonas-PR, região de baixa ocorrência de frio, em intervalos de 21 dias, de abril a agosto, e receberam ou não tratamento com frio suplementar de 1.440 horas, à temperatura de 4 a 7°C. As análises dos monossacarídeos foram realizadas em gemas e porções de ramos adjacentes a elas por cromatografia líquida de alta eficiência (HPLC). Houve acúmulo de glucose e frutose em gemas de macieira de abril a agosto, e este aumento foi estimulado pelo tratamento com 1.440 horas de frio. O conteúdo de glucose e frutose nos ramos adjacentes às gemas elevou-se de abril ao início de agosto, com posterior queda no final de agosto e o tratamento com frio antecipou esta dinâmica. O conteúdo de sorbitol em gemas e ramos de macieira oscilou de abril a agosto, e sua dinâmica foi alterada pelo frio.

Dinâmica do conteúdo de monossacarídeos em gemas e ramos de dois anos de macieira durante a endodormência

The objective of this work was to evaluate the variation of glucose, fructose and sorbitol content in two year old buds and stems of apple trees during the dormancy period. Stems of cv. Imperial Gala were collected in Porto Amazonas, Parana State, Brazil, a region of low chill occurence, at intervals of 21 days from April to August and were treated or not with 1,440 hours of chill (4 to 7°C). The monosaccharides were analysed in buds and stem tissues close to buds by high performance liquid chromatography (HPLC). There was an increase of glucose and fructose content in buds from April to August and it was stimulated by the chill treatment. The glucose and fructose content in stems increased from April to August 2nd followed by a reduction in August 23rd and the chill treatment advanced this dynamics. The sorbitol content in buds and stems of apple tree oscillated from April to August and its dynamics was modified by the chill treatment.

O objetivo do trabalho foi determinar as variações do conteúdo de glucose, frutose e sorbitol em gemas e ramos de dois anos de macieira que receberam ou não frio suplementar durante o período de dormência. Os ramos da cultivar Imperial Gala foram coletados em Porto Amazonas-PR, região de baixa ocorrência de frio, em intervalos de 21 dias, de abril a agosto, e receberam ou não tratamento com frio suplementar de 1.440 horas, à temperatura de 4 a 7°C. As análises dos monossacarídeos foram realizadas em gemas e porções de ramos adjacentes a elas por cromatografia líquida de alta eficiência (HPLC). Houve acúmulo de glucose e frutose em gemas de macieira de abril a agosto, e este aumento foi estimulado pelo tratamento com 1.440 horas de frio. O conteúdo de glucose e frutose nos ramos adjacentes às gemas elevou-se de abril ao início de agosto, com posterior queda no final de agosto e o tratamento com frio antecipou esta dinâmica. O conteúdo de sorbitol em gemas e ramos de macieira oscilou de abril a agosto, e sua dinâmica foi alterada pelo frio.

Variações do conteúdo de glucose, frutose e sorbitol em gemas e ramos de macieira durante a dormência

This research was aimed at evaluating the variations of glucose, frutose and sorbitol content in one year old buds and stems of apple trees during the dormancy period. The stems of cv. Imperial Gala were collected in Porto Amazonas, Parana State, Brazil, at intervals of 21 days from April to August (April 19th, May 10th, May 31st, June 21st, July 12th, August 2nd and August 23rd) and were treated or not with 1,440 hours of chill (4 to 7°C). The carbohydrates were analysed in buds and stem tissues close to buds by high performance liquid chromatography (HPLC). There was an increase of glucose, frutose and sorbitol content in apple tree buds during the dormancy. An increase of glucose and frutose content in stems occured until August 2nd followed by a significative reduction, while the sorbitol content decreased until June 21st followed by an increase until August 31st. The chill treatment during the dormancy period modified the variations of carbohydrate contents in buds and stems of apple tree.

O objetivo deste trabalho foi determinar as variações do conteúdo de glucose, frutose e sorbitol em gemas e ramos de um ano de macieira durante o período de dormência. Os ramos da cultivar "Imperial Gala" foram coletados em Porto Amazonas-PR, em intervalos de 21 dias, de abril a agosto (19/04, 10/05, 31/05, 21/06, 12/07, 02/08 e 23/08), e receberam ou não tratamento com frio suplementar de 1.440 horas à temperatura de 4 a 7°C. As análises dos carboidratos foram realizadas em gemas e porções de ramos adjacentes às primeiras por cromatografia líquida de alta eficiência (HPLC). Ocorreu um acúmulo de glucose, frutose e sorbitol nas gemas de macieira durante a dormência. O acúmulo de glucose e frutose nos ramos aconteceu até o início de agosto quando, em seguida, houve redução, enquanto o sorbitol decresceu até junho e, em seguida, elevou-se até o final de agosto. O tratamento com frio ao longo da dormência modificou as variações dos conteúdos de carboidratos nas gemas e ramos de macieira.

A aplicação de nitrogênio ao solo em diferentes estádios não afetou o rendimento de frutos de cultivares de macieira

Excess or deficiency of N have deleterious effects on apple yield and fruit quality. Since the rate of N uptake by apple trees depends on crop requirement within the season and on N available in the soil, it is important to know the need for supplemental N addition and the best application time. This study was carried out to evaluate the effect of timing of N application to the soil on fruit yield of apple cultivars. The experiments, one for 'Gala' and other for 'Fuji', were conducted from 1990 to 1996 in an orchard planted in 1988, with a density of 1481 trees ha-1, in an Oxisol with pH of 6.9, 4,0% of organic matter, and 60% of clay. Nitrogen treatments (50kg ha-1 year-1 during the first three growing seasons, and 60kg ha-1 year-1 afterwards) were applied at bud break (BB), or at petal fall (PF), or split 2/3 at BB + 1/3 at PF, or 2/3 at PF + 1/3 thirty-days later, always broadcast over the soil surface, without incorporation, in a 2-m-wide strip in the planting row. There was also a treatment without N addition. Average annual fruit yield varied from 40 to 112t ha-1 for 'Gala', and from 38 to 84t ha-1 for 'Fuji', and in the entire period it was 35% greater for 'Gala' than for 'Fuji'. Application of N to the soil, regardless of timing, had no effect on fruit yield, on N content in the leaves, and on canopy growth of both cultivars, in any year evaluated. It was assumed that N released from soil organic matter decay was sufficient to promote normal growth and high fruit productivity for these two apple cultivars.

Tanto o excesso quanto a deficiência de N causam efeitos negativos na produtividade e na qualidade dos frutos de macieira. Como a taxa de absorção de N pelas árvores de macieira é afetada pela demanda das mesmas, dentro da estação de crescimento, e pelo N disponível no solo, é importante conhecer a necessidade da adição suplementar desse nutriente e a melhor época para aplicá-lo. O presente trabalho objetivou avaliar o efeito da época de aplicação de N ao solo na produtividade de frutos de duas cultivares de macieira. Os experimentos, um para a Gala e outro para a Fuji, foram conduzidos de 1990 a 1996, em Vacaria, RS, num pomar plantado em 1988, na densidade de1481 árvores ha-1, sobre um Latossolo bruno com 4,0% de matéria orgânica, 60% de argila e pH 6,9. Os tratamentos constaram de 50kg de N ha-1 nos três primeiros anos, e 60kg de N ha-1 nas outras três safras, aplicados no inchamento das gemas (IG), ou na queda de pétalas (QP), ou dividido 2/3 no IG + 1/3 na QP, ou 2/3 na QP + 1/3 trinta dias após. O N foi sempre aplicado sobre a superfície do solo, sem incorporação, numa faixa de 2,0m ao longo da fila de plantio. Houve também um tratamento sem a aplicação de N. A produtividade média anual de frutos variou de 40 a 112t ha-1 para a cultivar Gala e de 38 a 76t ha-1 para a Fuji, e a produtividade média da Gala, no período, foi 35% superior à da Fuji. A aplicação de N ao solo, independentemente da época, não teve efeito na produtividade de frutos, no tamanho das brotações, na concentração de N nas folhas e no diâmetro do tronco das duas cultivares. Presume-se, portanto, que a quantidade de N liberada a partir da decomposição da matéria orgânica do solo foi suficiente para atender à demanda das plantas e permitir uma alta produtividade de frutos de macieira.

A aplicação de nitrogênio ao solo em diferentes estádios não afetou o rendimento de frutos de cultivares de macieira

Excess or deficiency of N have deleterious effects on apple yield and fruit quality. Since the rate of N uptake by apple trees depends on crop requirement within the season and on N available in the soil, it is important to know the need for supplemental N addition and the best application time. This study was carried out to evaluate the effect of timing of N application to the soil on fruit yield of apple cultivars. The experiments, one for 'Gala' and other for 'Fuji', were conducted from 1990 to 1996 in an orchard planted in 1988, with a density of 1481 trees ha-1, in an Oxisol with pH of 6.9, 4,0% of organic matter, and 60% of clay. Nitrogen treatments (50kg ha-1 year-1 during the first three growing seasons, and 60kg ha-1 year-1 afterwards) were applied at bud break (BB), or at petal fall (PF), or split 2/3 at BB + 1/3 at PF, or 2/3 at PF + 1/3 thirty-days later, always broadcast over the soil surface, without incorporation, in a 2-m-wide strip in the planting row. There was also a treatment without N addition. Average annual fruit yield varied from 40 to 112t ha-1 for 'Gala', and from 38 to 84t ha-1 for 'Fuji', and in the entire period it was 35% greater for 'Gala' than for 'Fuji'. Application of N to the soil, regardless of timing, had no effect on fruit yield, on N content in the leaves, and on canopy growth of both cultivars, in any year evaluated. It was assumed that N released from soil organic matter decay was sufficient to promote normal growth and high fruit productivity for these two apple cultivars.

Tanto o excesso quanto a deficiência de N causam efeitos negativos na produtividade e na qualidade dos frutos de macieira. Como a taxa de absorção de N pelas árvores de macieira é afetada pela demanda das mesmas, dentro da estação de crescimento, e pelo N disponível no solo, é importante conhecer a necessidade da adição suplementar desse nutriente e a melhor época para aplicá-lo. O presente trabalho objetivou avaliar o efeito da época de aplicação de N ao solo na produtividade de frutos de duas cultivares de macieira. Os experimentos, um para a Gala e outro para a Fuji, foram conduzidos de 1990 a 1996, em Vacaria, RS, num pomar plantado em 1988, na densidade de1481 árvores ha-1, sobre um Latossolo bruno com 4,0% de matéria orgânica, 60% de argila e pH 6,9. Os tratamentos constaram de 50kg de N ha-1 nos três primeiros anos, e 60kg de N ha-1 nas outras três safras, aplicados no inchamento das gemas (IG), ou na queda de pétalas (QP), ou dividido 2/3 no IG + 1/3 na QP, ou 2/3 na QP + 1/3 trinta dias após. O N foi sempre aplicado sobre a superfície do solo, sem incorporação, numa faixa de 2,0m ao longo da fila de plantio. Houve também um tratamento sem a aplicação de N. A produtividade média anual de frutos variou de 40 a 112t ha-1 para a cultivar Gala e de 38 a 76t ha-1 para a Fuji, e a produtividade média da Gala, no período, foi 35% superior à da Fuji. A aplicação de N ao solo, independentemente da época, não teve efeito na produtividade de frutos, no tamanho das brotações, na concentração de N nas folhas e no diâmetro do tronco das duas cultivares. Presume-se, portanto, que a quantidade de N liberada a partir da decomposição da matéria orgânica do solo foi suficiente para atender à demanda das plantas e permitir uma alta produtividade de frutos de macieira.

Soil nitrogen application in the spring did not increase apple yield

Since there is no chemical method to assess N availability from field soil samples, this nutrient is still recommended based on regional field trials. This study aimed to evaluate the effect of spring application of N to the soil on fruit yield of apple cultivars. Two experiments were carried out, respectively for ‘Gala and ‘Fuji. The trees, grafted on MM 106 rootstock, were planted in 1987, spaced 4.50 x 1.80m, in a clayed Oxisol (Hapludox) with 4.0% of organic matter, in Vacaria (RS), Southern Brazil. Treatments were applied annually, from the spring of 1990, in the tree row, over a 1.5-m-wide strip, as urea, and consisted of four rates of N corresponding to 0, 27.5, 55.0 and 82.5kg ha-1 in the first three years, and respectively 0, 50, 100 and 120kg ha-1 in the remaining two years. Data were collected for four years, starting at the 91/92 growing season. Application of increasing rates of N to the soil during five years had no effect on fruit yield and on concentration of N in the leaves regardless of year and cultivar. Average annual fruit yield varied from 50 to 70t ha-1 for ‘Gala and from 39 to 89t ha-1 for ‘Fuji, but in the entire period the average yield was similar for both cultivars, approximately 56t ha-1. Concentration of N in the leaves was always in the normal range (2.0 to 2.5%) for ‘Fuji, and slightly lower for ‘Gala, but above 1.9%. Total N requirement for tree growth and fruiting, thus, came from soil organic matter decay.

Como não existe método químico eficiente para avaliar a disponibilidade de N a partir de amostras de solo, a recomendação desse nutriente é ainda obtida a partir de curvas de resposta em experimentos regionais. O presente trabalho objetivou avaliar o efeito do N, aplicado ao solo na primavera, no rendimento de frutos de cultivares de macieira. Foram conduzidos dois experimentos, respectivamente com os cultivares Gala e Fuji, desenvolvidos sobre porta-enxerto MM 106. As árvores foram plantadas em 1987, espaçadas de 4,5 x 1,80m, num Latossolo bruno argiloso, com 4,0% de matéria orgânica, localizado em Vacaria (RS). Os tratamentos foram aplicados anualmente, durante a primavera, na forma de uréia, e consistiram de doses crescentes de N mineral equivalentes a 0, 27,5, 55, e 82,5kg ha-1 nos três primeiros anos, e respectivamente 0, 50, 100 e 200kg ha-1 nos dois últimos anos. A uréia foi aplicada numa faixa de 1,5m de largura ao longo da fila de plantio, sobre a superfície do solo, sem incorporação. A aplicação de N ao solo na primavera não afetou o rendimento de frutos e a concentração de N nas folhas, independente do ano ou do cultivar. A produtividade média anual de frutos variou de 50 a 70t ha-1 para a Gala e de 39 a 79t ha-1 para a Fuji. Na média dos quatro anos, porém, a produtividade foi semelhante para os dois cultivares, aproximadamente 56t ha-1. A concentração de N nas folhas ficou sempre dentro da faixa normal (2,0 a 2,5%) para a Fuji; para a Gala os valores foram um pouco mais baixos, porém sempre acima de 1,9%. A necessidade de N para o desenvolvimento das árvores e para a frutificação foi, portanto, completamente suprida pela decomposição da matéria orgânica do solo.

Soil nitrogen application in the spring did not increase apple yield

Since there is no chemical method to assess N availability from field soil samples, this nutrient is still recommended based on regional field trials. This study aimed to evaluate the effect of spring application of N to the soil on fruit yield of apple cultivars. Two experiments were carried out, respectively for ‘Gala’ and ‘Fuji’. The trees, grafted on MM 106 rootstock, were planted in 1987, spaced 4.50 x 1.80m, in a clayed Oxisol (Hapludox) with 4.0% of organic matter, in Vacaria (RS), Southern Brazil. Treatments were applied annually, from the spring of 1990, in the tree row, over a 1.5-m-wide strip, as urea, and consisted of four rates of N corresponding to 0, 27.5, 55.0 and 82.5kg ha-1 in the first three years, and respectively 0, 50, 100 and 120kg ha-1 in the remaining two years. Data were collected for four years, starting at the 91/92 growing season. Application of increasing rates of N to the soil during five years had no effect on fruit yield and on concentration of N in the leaves regardless of year and cultivar. Average annual fruit yield varied from 50 to 70t ha-1 for ‘Gala’ and from 39 to 89t ha-1 for ‘Fuji’, but in the entire period the average yield was similar for both cultivars, approximately 56t ha-1. Concentration of N in the leaves was always in the normal range (2.0 to 2.5%) for ‘Fuji’, and slightly lower for ‘Gala’, but above 1.9%. Total N requirement for tree growth and fruiting, thus, came from soil organic matter decay.

Como não existe método químico eficiente para avaliar a disponibilidade de N a partir de amostras de solo, a recomendação desse nutriente é ainda obtida a partir de curvas de resposta em experimentos regionais. O presente trabalho objetivou avaliar o efeito do N, aplicado ao solo na primavera, no rendimento de frutos de cultivares de macieira. Foram conduzidos dois experimentos, respectivamente com os cultivares Gala e Fuji, desenvolvidos sobre porta-enxerto MM 106. As árvores foram plantadas em 1987, espaçadas de 4,5 x 1,80m, num Latossolo bruno argiloso, com 4,0% de matéria orgânica, localizado em Vacaria (RS). Os tratamentos foram aplicados anualmente, durante a primavera, na forma de uréia, e consistiram de doses crescentes de N mineral equivalentes a 0, 27,5, 55, e 82,5kg ha-1 nos três primeiros anos, e respectivamente 0, 50, 100 e 200kg ha-1 nos dois últimos anos. A uréia foi aplicada numa faixa de 1,5m de largura ao longo da fila de plantio, sobre a superfície do solo, sem incorporação. A aplicação de N ao solo na primavera não afetou o rendimento de frutos e a concentração de N nas folhas, independente do ano ou do cultivar. A produtividade média anual de frutos variou de 50 a 70t ha-1 para a Gala e de 39 a 79t ha-1 para a Fuji. Na média dos quatro anos, porém, a produtividade foi semelhante para os dois cultivares, aproximadamente 56t ha-1. A concentração de N nas folhas ficou sempre dentro da faixa normal (2,0 a 2,5%) para a Fuji; para a Gala os valores foram um pouco mais baixos, porém sempre acima de 1,9%. A necessidade de N para o desenvolvimento das árvores e para a frutificação foi, portanto, completamente suprida pela decomposição da matéria orgânica do solo.