ABSTRACT The correct nutrition of orchards from fertilizer management directly influences fruit yield. Therefore, the objective was to evaluate the nutritional status of orchards of the ‘Montenegrina’ mandarin (Citrus deliciosa Tenore) grafted on Poncirus trifoliata Raf. in southern Brazil. The study included analyzes of soil and leaf tissue from 58 commercial orchards. More than 60% of the orchards were diagnosed with K and Mg insufficiency and more than 30% had an excess of N. There was an insufficiency in Mn and Zn of 60 and 96%, respectively, despite the levels of these micronutrients in the soil being high in both depths studied. In addition, no significant correlations were observed between the contents of a given nutrient in the soil and in the leaves, except for the Ca/Mg ratio. Insufficiency was observed in the leaf contents of K, Mg, Mn and Zn and excesses of N and Cu in the orchards. The use of phosphate and potassium fertilizers requires adjustments due to the excessive content of these nutrients in the soil. Pre-planting acidity correction and soil acidity management in ‘Montenegrina’ mandarin orchards already implanted needs to be optimized.

Abstract Gibberellins can promote the inhibition of floral induction in citrus in order to reduce alternate bearing. However, not much is known about the responsiveness of Citrus deliciosa to exogenous applications of gibberellic acid. Furthermore, the successive application of gibberellins is barely studied. The main objective of this work was to evaluate the effect of successive applications of gibberellic acid (GA3) on the reduction of spring flowering subsequent to low fruit load periods (off-year) in ‘Montenegrina’ and ‘Rainha’ mandarin trees, in southern Brazil. The treatments consisted of one to four successive applications of GA3 (40 mg L-1) with 21-day interval in off-year trees. Applications began in May and ended in July. There was a significant reduction in sprouting and flowering of ‘Montenegrina’ mandarin with more than two GA3 successive applications compared to the control. To ‘Rainha’ mandarin, only two GA3 applications reduced the sprouting and solely one GA3 application was enough to reduce sprouting in relation to the control. GA3 use reduced sprouting and flowering of Montenegrina and Rainha cultivars. The orchard age may be related to its level of alternate bearing and, therefore, to the greater or lesser sensitivity of gibberellin applications.

Resumo As giberelinas podem promover a inibição da indução floral em citros com intuito de reduzir a alternância de produção. Contudo, pouco se sabe sobre a responsividade de Citrus deliciosa às aplicações exógenas de ácido giberélico. Além disso, a aplicação sucessiva de giberelinas é pouco estudada. Desta forma, objetivou-se avaliar o efeito de aplicações sucessivas de ácido giberélico (AG3) sobre a redução do florescimento primaveril subsequente a safras de baixa carga de frutos (ano off) em tangerineiras ‘Montenegrina’ e ‘Rainha’, no Sul do Brasil. Os tratamentos consistiram em uma a quatro aplicações sucessivas de 40 mg L-1 de AG3, com intervalos de 21 dias, em plantas em ano off. O início das aplicações foi em maio, e o término, em julho. Houve redução significativa de brotação e de florescimento com mais de duas aplicações sucessivas de AG3 para a tangerineira ‘Montenegrina’ em relação ao controle. Para a tangerineira ‘Rainha’, apenas com duas aplicações de AG3, o florescimento foi reduzido, enquanto apenas uma aplicação já foi suficiente para reduzir a brotação em relação ao controle. O uso de AG3 reduz brotação e florescimento das cultivares Montenegrina e Rainha. A idade do pomar pode estar relacionada ao seu nível de alternância produtiva e, desta forma, à maior ou à menor sensibilidade a aplicações de giberelinas.

ABSTRACT The particle film technology has been reported as a promising tool in pest control. The objective of this work was to evaluate the efficiency of kaolin-based products against the oviposition of South American fruit fly, Anastrepha fraterculus (Dip.:Tephritidae), and its effect on the quality of citrus fruits. The experiment was conducted in orchards of ‘Okitsu’ tangerine and ‘Valencia’ orange trees in the 2017, 2018 and 2019 harvests. The treatments were as follows: 1) kaolin 10% + 0.1% Break-Thru® adjuvant; 2) Surround® 5% WP; 3) 0.15% phosmet (Imidan® 500 WP), 75 g. a.i.; 4) without application (control). The sprays were performed every 21 days. At harvest, fruits were individually packed in a greenhouse for inspection after 25 days and infestation was recorded. Fruit samples were evaluated for average diameter, average mass, soluble solids, titratable acidity and peel colorimetry. Infestation of A. fraterculus in tangerines was reduced in plants treated with the two kaolin-based products in the 2017 harvest. In the 2017 and 2019 crops, Surround® WP reduced the infestation and the number of puparium/fruits in oranges. The mineral films did not alter the physicochemical characteristics of the fruits, representing a promising alternative for the management of A. fraterculus.

ABSTRACT Mandarins commercialization at international market requires seedless fruit production in addition to its ideal organoleptic and visual quality. The objective of the work was to evaluate the efficiency of applications of gibberellic acid and of copper sulfate during anthesis in reducing the number of seeds and in the productive behavior of the 'Nadorcott' mandarin in the conditions of the southern Brazil. The experiment was performed in an orchard of 'Nadorcott' mandarin trees grafted on Poncirus trifoliata. Two applications were conducted at anthesis with different levels and combinations of gibberellic acid and copper sulfate. Also, net was used as one of the treatments to prevent pollination. Net treatment provided a high frequency of seedless fruits, with greater skin color, however with less production. Gibberellic acid applications increased linearly the frequency of seedless fruits and with a maximum of two seeds. Copper sulphate applications did not affect any evaluated characteristics. Sprays of gibberellic acid of 100 mg L-1 concentration reduce the number of seeds per fruit and increase parthenocarpy, without effect on fruit size and peel color.

Resumo Guabiju (Myrcianthes pungens), pertencente à família Myrtaceae, com ampla ocorrência no Rio Grande do Sul (RS), apresenta grande potencial para exploração de seus frutos no consumo in natura, com sabor adocicado, podendo compor bebidas, geleias e sorvetes, além de possuir propriedades nutracêuticas. As ferrugens, como característica principal, apresentam a formação de pústulas alaranjadas contendo urediniósporos do patógeno sobre os órgãos afetados. A ação do patógeno causa deformação dos órgãos: caules, folhas, flores e frutos, interferindo, assim, nos processos fisiológicos da planta. Assim, o presente trabalho teve como objetivo apresentar informações sobre a ocorrência, confirmação do agente causal da ferrugem do guabijuzeiro, além de relatar os acessos mais suscetíveis e resistentes a Austropuccinia na coleção de trabalho de guabijuzeiros em Eldorado do Sul-RS. A diagnose da doença foi realizada com base nos sintomas, na observação das estruturas fúngicas por microscopia óptica e por análises moleculares. A partir da microscopia, observaram-se urediniósporos elipsoides a ovoides e levemente equinulados, característicos de Austropuccinia sp. A sequência da região internal transcribed spacer(ITS) do isolado apresentou 99,06% de similaridade com sequências da mesma região da espécie A. psidii depositadas no banco de dados nucleotídeos - GenBank (NCBI). Este é o primeiro relato de ferrugem associada a guabijuzeiros no Estado do Rio Grande do Sul, Brasil. A partir da escala diagramática desenvolvida, foi possível identificar diferentes níveis de suscetibilidade a A. psidii nos acessos de guabijuzeiros avaliados.

Abstract Guabiju tree (Myrcianthes pungens) belongs to the Myrtaceae family, with wide occurrence in Rio Grande do Sul (RS), southern Brazil, demonstrates great commercial potential regarding the consumption of its fresh fruit, which has a sweet taste and can be used in drinks, jellies and ice creams, in addition to its nutraceutical properties. As their main characteristic, rusts present the formation of orange pustules containing urediniospores of the pathogen on affected organs. The action of the pathogen causes deformation of stems, leaves, flowers and fruits, thus interfer-ing with the physiological processes of the plant. Thus, the present work aimed at presenting information on the occurrence and confirmation of the causal agent of guabiju rust, in addition to reporting the accessions most susceptible and resistant to Austropuccinia in the guabiju working collection of Eldorado do Sul, RS, Brazil. The diagnosis of the disease was based on symptoms, observation of fungal structures by light microscopy and molecular analyses. From microscopy, ellipsoid to ovoid and slightly equinulate urediniospores were observed, characteristic of Austropuccinia sp. The sequence of the internal transcribed spacer (ITS) region of the isolate showed 99.06% similarity with sequences from the same region of A. psidii deposited on the nucleotide database - GenBank (NCBI). This is the first report of rust associated with guabiju in the state of Rio Grande do Sul, Brazil. From the diagrammatic scale developed, it was possible to identify different levels of susceptibility to A. psidii in guabiju accessions under study.

Resumo: O objetivo deste trabalho foi avaliar o número de aplicações sucessivas de ácido giberélico (GA3), no período de outono-inverno, quanto a seu efeito na redução do florescimento, na primavera subsequente após períodos de baixa carga de frutos (ano “off”), em tangerineiras 'Montenegrina' (Citrus deliciosa). As aplicações sequenciais a 40 mg L-1 de GA3 foram testadas de uma a quatro vezes, com intervalos de 21 dias, com início no final de maio. O experimento foi realizado em delineamento de blocos ao acaso, com quatro tratamentos e controle, quatro repetições e uma planta por unidade experimental. Floração, brotação, tipos de brotos, frutificação e diâmetro dos frutos foram avaliados. A frutificação diminui exponencialmente com o aumento da intensidade de floração. O uso de GA3 em duas, três ou quatro aplicações sequenciais, de maio a junho, maio a julho e maio a agosto, reduz a intensidade de floração e brotação em plantas com produção alternada na primavera subsequente, o que aumenta os brotos mistos e reduz os brotos florais. O uso de quatro aplicações sequenciais de 40 mg L-1 de GA3 promove grande incremento na frequência de brotos campaneiros e favorece o aumento da fixação e do tamanho dos frutos.

Abstract: The objective of this work was to evaluate the number of successive applications of gibberellic acid (GA3), during the autumn-winter period, for its effect on the reduction of flowering, in the subsequent spring after periods of low fruit load (off-year), in 'Montenegrina' mandarin trees (Citrus deliciosa). Sequential applications at 40 mg L-1 GA3 were tested from one to four times, at 21-day intervals, beginning in the end of May. The experiment was carried out in a randomized complete block design, with four treatments and a control, four replicates, and one plant per experimental unit. Flowering, sprouting, types of shoots, fruit set, and fruit diameter were evaluated. The fruit set increases exponentially with the reduction of flowering intensity. The use of GA3 in two, three, or four sequential applications, from May to June, May to July, and from May to August, at 21-day intervals, reduces the intensity of flowering and sprouting of alternate bearing plants in the subsequent spring, increasing mixed shoots and reducing floral shoots. The use of four sequential applications of 40 mg L-1 GA3 promotes a great increase in the frequency of single flower terminal leafy shoots and favors the increase of fruit fixation and size.

SUMMARY: Butia odorata is an endangered palm tree native of southern Brazil and Uruguay with great food and ornamental potential. The lack of phytotechnical information hinders the commercial production of their seedlings. The aim of this work was to test doses of fertilization on the formation of B. odorata seedlings and tolerance to salinity levels in the substrate. The seedlings were cultivated in containers, submitted to control and four doses of fertilizer per liter of substrate. We evaluated stem diameter, number of leaves and pinnate leaves, electrical conductivity (EC) and pH of the substrate. The experimental design was in random blocks with 10 plants per treatment. Dry density, air space, and total pore space of the substrate were within the ideal ranges, such as EC and pH, without a significant trend for these last two variables in relation to the doses of fertilizers. Throughout the experiment, the pH remained adequate, except for higher dosage treatments that acidified the substrate. EC increased gradually, except for control treatment. There was a significant difference between treatments and blocks for plant variables, with the second access plants presenting larger stem diameter. The dosages that induced higher responses were 0.6 and 1.2 g L-1 with EC corresponding to 5 mS cm-1, which is possibly the limit of salts in the substrate tolerated by the species. B. odorata responded positively to the fertilization during the formation of the seedlings. However, until the juvenile phase, its development is impaired if EC reaches 5 mS cm-1.

RESUMEN: Butia odorata es una palmera en peligro de extinción originaria del sur de Brasil y Uruguay con gran potencial alimenticio y ornamental. La falta de información fitotécnica dificulta la producción comercial de sus plantas. El objetivo de este trabajo fue evaluar fertilización en la formación de plantas de B. odorata y su tolerancia a la salinidad del sustrato. Las plantas se cultivaron en contenedores, sometidas a control y cinco dosis de fertilizante. Fueron evaluados: diámetro del tallo, número de hojas y hojas pinnadas, conductividad eléctrica (EC) y pH del sustrato. El diseño experimental fue en bloques aleatorizado con 10 plantas por tratamiento. La densidad aparente, el espacio de aire y el volumen total de poros del substrato estuvieron dentro de rangos ideales; también la EC y el pH, sin tendencia significativa para estas dos últimas variables en relación con las dosis de fertilizantes. El pH se mantuvo adecuado, excepto con dosis más altas que acidificaron el sustrato. La EC aumentó gradualmente, excepto para el tratamiento de control. Hubo diferencia significativa entre tratamientos y bloques para las variables de la planta. Las dosis que indujeron respuestas mayores fueron 0,6 y 1,2 g L-1 con EC de 5 mS cm-1, que es posiblemente el límite de sales en el sustrato tolerado por la especie. Butia odorata respondió positivamente a la fertilización durante la formación de las plantas. Sin embargo, hasta la fase juvenil, su desarrollo se vio afectado cuando la EC alcanzó 5 mS cm-1.

Resumo O conhecimento sobre a quantidade de nutrientes exportados por frutas cítricas é uma ferramenta adequada para estimar a reposição de nutrientes, e estas informações para tangerinas são escassas. Nesse contexto, o objetivo deste estudo foi determinar o teor e a exportação de nutrientes pela colheita de frutos de tangerineiras, em um pomar manejado sob sistema orgânico de produção. Um experimento foi realizado em um pomar orgânico de tangerineiras adultas (23 anos), localizado no Rio Grande do Sul, Brasil. O teor total de macronutrientes e de micronutrientes foi determinado nos frutos de tangerina, e a exportação foi estimada pela produtividade média de duas safras (2013/2014 e 2014/2015). A exportação média de macronutrientes foi de 3,3; 2,3; 1,3; 0,4 e 0,3 kg t-1 para N, K, Ca, P e Mg, respectivamente; e de micronutrientes foi de 6,3; 4,6; 1,5; 0,7 e 0,5 g t-1 para Fe, B, Zn, Mn e Cu, respectivamente. A exportação de N pelas tangerinas não condiz com as informações atuais utilizadas para recomendações de adubação em citros, sendo o K o elemento mais exportado. Em relação aos micronutrientes, além de as quantidades exportadas variarem entre a literatura, a ordem de magnitude segue a mesma observada em nosso estudo. Propomos esses novos padrões para reposição de macronutrientes e de micronutrientes em pomares estabelecidos de tangerina sob manejo orgânico, contribuindo para uma recomendação de adubação mais precisa.

Abstract The knowledge on the amount of nutrients exported by citrus fruit is an adequate tool to estimate nutrient demand reposition and this information about mandarin is very scarce. In this context, the objective of this study was to determine the nutrient content and exportation by mandarin fruits harvest, in an orchard managed under organic production system. An experiment was carried out in an organic orchard of adult mandarin trees (23 years), located in Rio Grande do Sul State (Brazil). The total content of macronutrients and micronutrients was determined in the mandarin fruits and the exportation was estimated by average yields in two seasons (2013/2014 and 2014/2015). The average exportation of macronutrient was 3.3, 2.3, 1.3, 0.4 and 0.3 kg t-1 for N, K, Ca, P and Mg, respectively; and of micronutrients was 6.3, 4.6, 1.5, 0.7 and 0.5 g t-1 for Fe, B, Zn, Mn and Cu, respectively. The N exportation in mandarin fruits does not comply with the current information used for citrus fertilizer recommendations, where the K is the nutrient most exported. Regarding micronutrients, besides the exported amounts vary among the literature, the magnitude order follows the same observed in our study. We propose these new standards for reposition of macronutrients and micronutrients in established mandarin orchards under organic management, contributing to a more accurate fertilizer recommendation.

Abstract The propagation of guabijuzeiro (M. pungens) by seed is originating plants with high genetic variability and a long juvenile period. Therefore, the objective was to study the multiplication and rooting in vitro of guabijuzeiro in order to get information to enable the clonal propagation. In the multiplication, apical and nodal segments were used, taken from in vitro plantlets, combined with 6-Benzylaminopurine (BAP), naphthaleneacetic acid (NAA) and gibberellic acid (GA). In the rooting, NAA and IBA (indolebutyric acid) were used. The results showed that in the multiplication there was superiority in media with BAP, while rooting was not satisfactory in media with NAA or IBA. Thus, it is possible to multiply M. pungens in vitro using BAP phytoregulator in the multiplication stage. However, the rooting stage needs more tests to induce the production of roots and facilitate acclimatization of the plants obtained in vitro.

Abstract Seasonality and lack of organic substrates suitable for the production of citrus rootstocks are the main problems in seedling production, coupled with the fact that these materials have alkaline pH. The objective of this study was to evaluate the effect of substrates composed of Pinus sp. needles and a commercial alkaline substrate at different concentrations on the growth and development of Poncirus trifoliata (L.) Raf rootstock. The development of 'Trifoliata' was assessed in different mixtures (v:v) of a commercial substrate (Vida®) based on eucalyptus bark and Pinus sp. needles (0, 25, 50, 75 and 100 %) with two particle sizes (3.5 and 8.0 mm). A randomized block experimental design with 10 treatments of seven plants each and four replications was used. During rootstock development, we monitored: the pH, electrical conductivity and stability of the substrates; the dry mass of the aerial part, roots and stem; and vegetative growth and development. Increasing the proportion of needles in the mixture with alkaline substrate reduced the pH, electrical conductivity and density. Treatments with 3.5 mm needles showed greater stability than those with 8 mm ones. The use of 25 % needles provided better results compared to 0 % (alkaline substrate only); however, the need for a specific fertilization and irrigation system for each treatment was detected, as each new substrate has its own physical and chemical characteristics.

Resumen La estacionalidad y carencia de sustratos orgánicos adecuados para la producción de portainjertos cítricos son de los principales problemas en la producción de plántulas, aunado al hecho de que estos materiales poseen pH alcalino. El objetivo de este trabajo fue evaluar el efecto de sustratos compuestos de acícula de Pinus sp. y un sustrato comercial alcalino a diferentes concentraciones sobre el crecimiento y desarrollo del portainjerto Poncirus trifoliata (L.) Raf. Se evaluó el desarrollo de ‘Trifoliata’ en distintas mezclas (v:v) de un sustrato comercial (Vida®) a base de corteza de eucalipto y acículas de Pinus sp. (0, 25, 50, 75 y 100 %) con dos granulometrías (3.5 y 8.0 mm). El diseño experimental fue en bloques al azar con 10 tratamientos de siete plantas cada uno y cuatro repeticiones. Durante el desarrollo de los portainjertos se monitoreó el pH, la conductividad eléctrica y la estabilidad de los sustratos, la masa seca de la parte aérea, raíces y tallo, además del crecimiento y desarrollo vegetativo. El aumento de la proporción de acículas en la mezcla con sustrato alcalino redujo el pH, la conductividad eléctrica y la densidad. Los tratamientos con acícula de 3.5 mm mostraron mayor estabilidad que los de 8 mm. El uso de 25 % de acícula proporcionó mejores resultados en comparación con el de 0 % (solo sustrato alcalino); no obstante, se detectó la necesidad de un sistema de fertilización y riego específico para cada tratamiento, ya que cada sustrato nuevo posee características físicas y químicas propias.

Resumo O guabijuzeiro (Mycianthes pungens (O. Berg) Legrand) é uma frutífera que apresenta grande potencial para exploração comercial de seus frutos devido às suas características nutricionais. O objetivo deste trabalho foi estudar o ciclo reprodutivo de M. pungens, entre os anos de 2014 e 2015, em distintas regiões do Rio Grande do Sul: acessos de guabijuzeiros dos municípios de Três Passos (região noroeste), Paraí e Guabiju (região nordeste) e Porto Alegre (região Metropolitana). Como resultados, observaram-se variação na fenologia e soma térmica entre os acessos, sendo que, em Três Passos, o ciclo reprodutivo teve duração de 95 dias e atingiu soma térmica de 1.290 °C. No município de Guabiju, o ciclo reprodutivo teve duração de 147 dias, e a soma térmica foi de 1.603 °C. No município de Porto Alegre, o ciclo reprodutivo foi de 133 dias, e a soma térmica, de 1.564 °C.

Abstract Guabiju (Mycianthes pungens (O. Berg) Legrand) is a fruit tree with great potential for commercial exploitation due to its nutritional characteristics. The aim of this work was to study the reproductive cycle of M. pungensin different regions of Rio Grande do Sul. Phenology was monitored from September 2014 to February 2015 in the municipalities of Três Passos (Northwestern region), Parai and Guabiju (Northeastern region), and Porto Alegre (Metropolitan region). As results, variations in reproductive cycle and thermal sum among accessions were observed, and in Três Passos, the reproductive cycle had duration of 95 days and reached thermal sum of 1290°C. In the municipality of Guabiju, the reproductive cycle lasted 147 days and the thermal sum was 1603°C. In the municipality of Porto Alegre, the reproductive cycle had duration of 133 days and the thermal sum reached 1564°C.

ABSTRACT: Seedlessness in fruit is a trait that is much sought after by juice making industries. Close to the city of São Sebastião do Caí, in the state of Rio Grande do Sul (RS), Brazil, a new mutant orange originating from natural mutation was identified and selected as a seedless material. To determine the mechanisms involved in the absence of seeds, the reproductive structures of this new mutant by comparison with a Valencia sweet orange as control, a cultivar with a profusion of seeds, was analyzed in terms of meiotic behavior, meiotic index, pollen viability, in vitro germination, and ovule features to determine the grounds for seed absence. Other morphological analyzes allowed for visualizing the structures of normal appearance and size in both cultivars. Meiotic analysis identified chromosome normal pairing with a predominance of bivalents at diakinesis and metaphase 1. URS Campestre flowers at different developmental stages had anthers and ovaries whose dimensions are typical while pollen grain analysis pointed to a standard developmental pattern, normal meiosis, high viability (84 %) and elevated in vitro pollen tube germination rates (63 %). The cv. Valencia and URS Campestre ovules had a similar shape and morphology, sharing an anatropous orientation, and two integuments. In the internal ovule analyses of Valencia sweet oranges, normal embryo sac cells were identified: presence of one egg cell and two synergids, three antipodes and a bigger and central cell containing two polar nuclei. However, the analysis of ovules from URS Campestre reveals an apparent senescence or non-formation of an embryo sac, where only a few highly stained and collapsed cells could be identified. These results led to the conclusion that female sterility in URS Campestre, with a total absence of a female gametophyte, is the limiting factor for fertilization and seed production.

RESUMO: A tangerineira 'Montenegrina' ( Citrus deliciosa Tenore) é amplamente cultivada no sul do Brasil. Possui grande tendência à alternância de produção, necessitando de raleio de frutos. Contudo, os raleantes químicos estudados até hoje nesta cultivar não se demonstraram eficientes. Este trabalho teve como objetivo avaliar o efeito do ácido 3,5,6-tricloro-2-piridiniloxiacético (3,5,6-TPA) sobre a produção e qualidade de frutos da tangerineira 'Montenegrina', em relação às opções de raleio químico previamente estudadas. Foram utilizados, como padrão, raleio manual e plantas sem raleio (controle). Realizaram-se aplicações de ethephon em três doses: 200mg L-1, 300mg L-1 e 200mg L-1 + 3% de ureia; e aplicações de 3,5,6-TPA, em quatro doses: 10, 20, 30 e 40mg L-1. Os frutos de árvores raleadas manualmente e de tratadas com 3,5,6-TPA a 40mg L-1 apresentaram maior tamanho médio, melhor distribuição de calibres comerciais e cores mais alaranjadas. Nenhum tratamento reduziu a alternância de produção. Aplicações de 40mg L-1 de 3,5,6-TPA como raleante químico, durante a queda fisiológica de frutos jovens, propiciaram efeito similar ao raleio manual sobre a produção e qualidade dos frutos de tangerineira 'Montenegrina'.

ABSTRACT: The 'Montenegrina' mandarin ( Citrus deliciosa Tenore) is widely cultivated in southern Brazil. This cultivar has a great tendency for alternate bearing, requiring thining of the fruit. However, the chemical thinners studied until now in this cultivar have not been successful. The objective of this research was to evaluate the effect of 3,5,6-trichloro-2-pyridinyloxyacetic acid (3,5,6-TPA) on the production and fruit quality of the 'Montenegrina' mandarin, in comparison with hand thinning and the options of chemical thinning previously studied. Hand thinning and no thinning were used as controls. Ethephon was applied in three doses: 200mg L-1, 300mg L-1 or 200mg L-1 + 3% urea; or 3,5,6-TPA, in four doses: 10, 20, 30 or 40mg L-1. Fruits of the hand thinned trees and those treated with 40mg L-1 showed greater average size, greater distribution of commercial caliber and more orange colors. No treatment reduced alternate bearing. Applications of 40mg L-1 of 3,5,6-TPA as a chemical thinner, during the physiological drop of young fruit, had a similar effect that of hand thinning over yield and quality of fruits of 'Montenegrina' mandarin.

Abstract This study aimed to evaluate the genetic and cytological diversity and stability of 35 cherry tree accessions collected in Rio Grande do Sul. We used 15 RAPD (Random Amplified Polymorphic DNA) molecular markers and performed cytological analysis and number count of anthers. Analyses of genetic diversity allowed the separation of accessions into four groups, resulting in an average of 8.93 bands per primer amplified, 7.89 polymorphic bands, 88.08% of polymorphism and 86% of genetic similarity. Cytological analyses of gametic cells allowed for the characterization of accessions as diploids with n=11. In these, the average of meiotic cells considered normal was 82.12%; average pollen viability was 92.44% and in vitro germination was 40.26%; the average number of anthers was 161.85 anthers/flowers. Therefore, the accessions evaluated showed high genetic similarity and cytological stability and can be used in commercial plantations or hybridizations.

RESUMO A propagação por estaquia é uma alternativa para a obtenção de porta-enxertos de citros. A aplicação exógena de ácido indolbutírico (AIB), época de coleta das estacas e genótipos utilizados exercem efeito sobre o enraizamento e desenvolvimento de estacas de porta-enxertos de citros. Para estudar o efeito desses fatores, dois experimentos foram realizados. No primeiro, estacas semilenhosas dos híbridos de tangerineira 'Sunki' H49 e H77 foram coletadas no outono e final da primavera de 2013, sendo tratadas com AIB (0 mg L-1, 1.500 mg L-1 e 3.000 mg L-1). Em cada época de coleta, utilizou-se o esquema fatorial 2 x 3 (dois genótipos x três concentrações de AIB), sob delineamento em blocos casualizados. No segundo experimento, avaliou-se o desenvolvimento das estacas que enraizaram na primavera, até atingirem o ponto de enxertia. Neste caso, adotou-se o delineamento experimental inteiramente casualizado, com os híbridos H49 e H77. Os tratamentos com AIB influenciaram positivamente no enraizamento e número de raízes somente na coleta de outono, alcançando índice máximo de 23,3 % de estacas enraizadas. Na coleta do final da primavera, o enraizamento ficou próximo a 100 %, sendo desnecessário o uso de AIB. Cerca de 50 % das estacas dos híbridos de tangerineira 'Sunki' atingiram o ponto de enxertia 14 meses após a estaquia.

ABSTRACT Propagation by cuttings is an alternative for obtaining citrus rootstocks. The exogenous application of indolebutyric acid (IBA), cutting collection season and genotypes used may affect the rooting and vegetative growth of citrus rootstocks cuttings. Two experiments were conducted to study the influence of these factors. In the first one, semi-hardwood cuttings from the 'Sunki' mandarin hybrids H49 and H77 were collected in the fall and late spring of 2013 and treated with IBA (0 mg L-1, 1,500 mg L-1 and 3,000 mg L-1). For each collection season, a 2 x 3 (two genotypes x three IBA concentrations) factorial scheme was adopted, in a randomized blocks design. In the second experiment, the development of cuttings that rooted in the late spring was evaluated until grafting. In this case, a completely randomized experimental design was adopted, with the hybrids H49 and H77. The IBA treatments positively influenced rooting and number of roots only in the fall collection, peaking at 23.3 % of rooted cuttings. In the late spring collection, rooting was close to 100 %, with the IBA treatment being unnecessary. Around 50 % of cuttings from the 'Sunki' mandarin hybrids were ready for grafting at 14 months after cutting.