Folha Murcha Research Articles

Ciclo fenológico e acúmulo térmico em genótipos de laranjeiras-doces no Sul do Brasil

Abstract The aim of this work was to study the phenology of several sweet orange cultivars and their relationship with the accumulated degree-day (ADD), under the conditions of the Depressão Central of Rio Grande do Sul, in Southern Brazil. For this, 25 genotypes were evaluated for three consecutive growing seasons between 2015 and 2018. The experiment was carried out in a Citrus Collection located in municipality of Eldorado do Sul, RS, Brazil. The ADD was calculated for each interval between the phenological stages, as well as for the entire cycle. The first one, swelling of the buds, was concentrated between mid-July and early August. Sprouting in winter increased the risk of frost damage. Full bloom occurred between August 28 and September 22, when the orange trees ‘Cabula’, ‘Rubi’, ‘Lima Verde’ and ‘Folha Murcha’ were the first to bloom and ‘Sanguinea’, ‘Salustiana’, ‘Midknight’ and ‘Jaffa’ the last. The last stage evaluated, the skin color change of the fruits, occurred between the beginning of April and the end of May, with 2,306.4 to 2,619.4 ADD, since the beginning of sprouting. The orange trees showed different behavior when compared between genotypes and between years. Two groups of cultivars were defined: early and late.

Germplasm Diversification in Citrus Orchards in a Mesothermal Climate in Brazil

The limited scion-rootstock combinations used in sweet orange orchards in Brazil reduce the commercial potential of citrus and lead to greater susceptibility to pests and diseases. Aiming to provide germplasm diversification, the research evaluated the Folha Murcha (FM) and Charmute de Brotas (CB) orange trees grafted onto ‘Rangpur’ lime (RL) and ‘Swingle’ citrumelo (SC) rootstocks. The study was conducted in the southern center of the state of São Paulo, in the subtropical region of southeastern Brazil. The grafted trees were planted in September 2016. The field experiment was conducted over two seasons. The combinations were evaluated based on the duration in days and degree-days of the phenological intervals, growth and yield performance, alternate bearing, fruit ripening, and quality. The trees of the two scion cultivars grafted onto RL had the shortest crop cycle, the earliest fruit ripening, and the largest canopy volume. SC produced fewer alternate bearings with greater production efficiency. The CB/SC combination produced fruits with a better color index, higher total soluble solids content, and a higher technological index. This assessment can be useful in planning orchards for dual-purpose markets, such as table fruit and the juice industry.

Caracterização físico-química de frutos de laranjeira-doce sobre diferentes porta-enxertos

ABSTRACT The objective of this study was to evaluate the physico-chemical characteristics of fruits of 58 sweet orange tops cultivars on four rootstocks, namely: ‘Sunki Tropical’ mandarin and ‘Trifoliata’ Citrandarin ‘San Diego’, ‘Riverside’ and ‘Indio’. For this purpose, a completely randomized experimental design was used, in a factorial scheme (58 x 4). The characteristics analyzed were: equatorial diameter, fruit mass, peel thickness, number of seeds, soluble solids, titratable acidity, Ratio and juice yield. All the characteristics analyzed were influenced by both the tops cultivar and the rootstock, demonstrating that both factors interfere in the physicochemical quality of the fruits. The tops ‘Pera D-3’, ‘Pera Olimpia’, ‘Pera Bianchi’, ‘Jaffa’ and ‘Westin’ on all rootstocks evaluated showed characteristics in their fruits with soluble solids greater than 10 ºBrix, Ratio above 9.5 and juice yield greater than 45%, characteristics that define fruits with quality standards. Also, the tops ‘Pera Olimpia’, ‘Sincorá’ and ‘Westin’ on the rootstock ‘Sunki Tropical’, ‘Pera D-3’, ‘Pera D-25’, ‘Sincorá’, ‘Aquiri’ and ‘Russas P.S.’ on the rootstock ‘San Diego’, ‘Pera C-32’, ‘Pera D-3’, ‘Pera D-6’, ‘Pera E-6’, ‘Pera Bianchi’, ‘Pera CE-03 ‘, ‘Salustiana’ and ‘Westin’ on ‘Riverside’ rootstock are suitable for the juice production industry with Ratio between 14 and 16 and juice yield greater than 50%. It is also worth noting that the tops ‘Crescent’, ‘Natal Folha Murcha’, ‘Valencia Midknight’ and ‘Valencia Delta’ produced fruits without seeds on all rootstocks.

Late-Season Sweet Orange Selections Under Huanglongbing and Citrus Canker Endemic Conditions in the Brazilian Humid Subtropical Region.

The Brazilian citrus orchards are comprised by few genotypes, which increases the risk of pest and disease outbreaks. The diversification of sweet oranges (Citrus × sinensis) in orchards also generates off-season revenue and extend the fruit processing period. This study aimed to evaluate several horticultural traits of 19 late-season sweet orange selections under citrus canker and huanglongbing (HLB) endemic condition in northwestern Paraná state, Brazil, in a long-term field experiment. Tree size, yield, fruit quality for fresh fruit and industrial markets, estimates of tree density and yield, and citrus canker and huanglongbing (HLB) incidences were assessed. The experimental design was a randomized block with three replicates and five trees per unit. The orchard was drip-irrigated and arranged at tree spacing of 6.5 m × 4.5 m. All scions were graft-compatible with Rangpur lime (C. × limonia). Valencia selections had the tallest trees and largest canopies, particularly Olinda, Frost and #121 with heights and volumes greater than 4.20 m and 43 m3, respectively. Natal África do Sul and Whit’s Late Valencia trees were the most productive with cumulative yields above 640 kg per tree. Most of the selections produced fruits of excellent physicochemical quality attending the fresh fruit and industrial market requirements. All selections showed similar horticultural characteristics for the fresh market, while Natal África do Sul and Charmute de Brotas were more suitable for juice processing. Frost Valencia and Valencia Late Fla. had the highest incidence of citrus canker on fruits (>20%), whereas IPR Folha Murcha, Charmute de Brotas and some Valencia selections (Chafeei Late, Campbell 479, Campbell 294, Olinda, Mutação and Whit’s Late) exihibed low incidence (3.0–17.7%). At 9 years, Valencia Mutação trees had high HLB incidence (93%). In contrast, Natal IAC and Folha Murcha IAC showed the lowest HLB incidence (13%). Our results revealed that Natal IAC, Folha Murcha IAC, IPR Folha Murcha, Natal Murcha, Campbell 479 Valencia and Valencia Late Fla. had the best horticultural performance in addition to low HLB incidence. Together, these late-season sweet oranges are the most advantageous selections for citrus orchard diversification under citrus canker and HLB endemic conditions in humid subtropical regions.

Fast and eco-friendly method using atmospheric solids analysis probe mass spectrometry to characterize orange varieties.

Orange fruit is one of the most popular types of fruit in the world, and its juice is the main product of its processing. This study aimed to evaluate a simple, fast, and eco-friendly methodology, atmospheric solids analysis probe mass spectrometry (ASAP-MS), to assess the chemical profile of four oranges varieties (Valencia, Folha Murcha, Pera, and Iapar). The oranges' varieties were evaluated for the physicochemical composition (extraction yield, pH, total titratable acidity, total soluble solids [TSS], °Brix), ratio (TSS/TA), and bioactive compounds (ASAP-MS analysis). The characterization of oranges resulted in great values of oranges yield according to the varieties (44.00-48.10% [w/w], adequate and characteristic acidity [0.73-1.35%], soluble solids content (10.24-13.80°Brix), pH (3.30-3.96), and ratio (7.59-19.90) level for this fruit. This powerful method showed that all analysis procedures were simple, fast, and easy because there is no need to prepare the sample and the analysis time lasted 2 min. Besides, results obtained exhibited a vast array of chemical groups. Principal component analysis (PCA) defined and distinguished the varieties of the orange. Therefore, ASAP-MS and PCA showed that they are very attractive candidates for routine analysis to monitor the varieties of the orange with its pronounced advantages, besides being contributing to the environment because it does not use any quantities of organic solvents. This methodology was applied for the first time to this type of sample.

Modeling seasonal flushing and shoot growth on different citrus scion-rootstock combinations

Occurrence, intensity, and growth patterns of new shoots (NS) were evaluated in orchards of ‘Pera’ and ‘Folha Murcha’ sweet oranges (Citrus × aurantium var. sinensis L.), ‘Ponkan’ mandarin (C. reticulata Blanco) and Persian lime (C. × latifolia var. latifolia) grafted on nine rootstocks to determine potential impacts of scion-rootstock combinations on NS growth parameters favorable to Diaphorina citri. NS number and the area under flush shoot dynamics were used to compare NS intensities. NS number (dependent variable) and meteorological elements (independent variables) were used through multiple linear regression to describe NS occurrences. NS growth data were compared through non-linear regression based on degree-days. NS occurrence dynamics were similar for all combinations, but the intensity was significantly higher on ‘Florida’ rough lemon than on ‘Flying Dragon’ trifoliate. Occurrence of NS on ‘Pera’, ‘Folha Murcha’ and Persian varieties associated positively (P < 0.05) with an increase of minimum and average temperatures (avg. adjusted R2 = 0.406; 0.408; 0.403, respectively), whereas on ‘Ponkan’ was related to the accumulated rainfall (avg. adj. R2 = 0.311). NS grew faster and attained longer lengths during spring (102.7 mm during 34 days) than autumn (71.9 mm during 42 days), except for ‘Folha Murcha’ which took longer to grow and reached shorter lengths (78.8 mm during 38 days) during spring, and longer lengths during autumn (118.3 mm during 42 days). Logistic models better fitted NS growth data (avg. adj. R2 ≥ 0.94). The adjusted R2 values of regression models developed to predict NS occurrence during the study were not high enough to estimate optimum timing to start insecticide applications for the control of D. citri. However, the adjusted R2 values attained for NS growth can be used to improve timing, and thereby adjust frequency of insecticide applications.

Tree growth, production and huanglongbing incidence of sweet orange varieties using different nursery tree standards

Insect-proof propagation of citrus is recommended to prevent vector-transmitted pathogens such as Candidatus Liberibacter spp. and Xylella fastidiosa. Although larger nursery trees were related to a superior post-planting performance in other perennial crops, there are few studies on citrus. This fact motivated us to evaluate the tree growth, the fruit production, and the huanglongbing (HLB) incidence of four commercial sweet orange varieties (‘Valencia Late’, ‘Hamlin’, ‘Pera’ and ‘Folha Murcha’) using two nursery tree standards (young whip and large headed trees). Eight years after planting, the tree size was similar between the evaluated treatments, especially for more vigorous varieties. However, large headed trees anticipated and increased the cumulative production by 30 % in average, which can improve the performance of reset trees in particular. Regardless the nursery tree standard and sweet orange variety, the cumulative incidence of HLB was relatively high over eight years. Therefore, a strict control of the vector should be reinforced in the field irrespectively of these factors.

Revisiting seed transmission of ‘Candidatus Liberibacter asiaticus’ in different citrus species and hybrids

Huanglongbing (HLB) caused by ‘Candidatus Liberibacter spp.’ is the most destructive disease for citrus production. These bacteria are disseminated naturally by insect vectors, such as the psyllid Diaphorina citri. However, the transmission of the bacteria vertically from seeds to seedlings has been controversial. Therefore, the objective of this study was to re-investigate the vertical transmission of the bacterium ‘Ca. Liberibacter asiaticus’ (CLas) from seeds to seedlings. Seeds of ‘Rangpur’ lime, ‘Swingle’ citrumelo, ‘Ponkan’ mandarin and the sweet oranges ‘Folha Murcha’, ‘IAPAR-73’, ‘Pera Rio’, ‘Shamouti’ and ‘Valencia’ were included in the study. Besides the seeds, 3493 citrus seedlings were also examined for the presence of the bacterium and for the development of HLB symptoms. The presence of the bacterium in different parts of the seeds and in citrus seedlings was examined by standard PCR. CLas was detected in all parts of the seeds, including seed coat or testa, tegmen, and endosperm plus embryos of all citrus cultivars, except for ‘Shamouti’ sweet orange. Although transient, the presence of the HLB bacterium was also detected in seedlings of ‘Ponkan’ mandarin and ‘Folha Murcha’ sweet orange obtained from seeds of HLB-infected trees up to 18 months after seedlings transplanting. However, no typical symptoms of HLB were observed in the citrus seedlings. Although CLas may infect the citrus seeds, the results of this study do not support the vertical transmission of viable cells of CLas from seeds to seedlings.

Influência do sombreamento no crescimento de mudas de laranjeira ‘Folha Murcha’

The system of production of certified seedlings demand studies on the behavior of plants in different levels of shading. The objective of this study was to evaluate the effect of different levels of shading on the growth of ‘Folha Murcha’ orange grafted on the Rangpur lemon rootstock. The design was completely randomized with treatment consisting of four levels of shading (0%, 30%, 50%, e 80%), with six replications and one plant per plot. At 145 days after grafting the diameter of the rootstock, the graft diameter and height, leaf number, leaf area and shoot dry mass were evaluated. Graft height and leaf number were not influenced by the different levels of shading but the other plant characteristics were. According to the results, higher growth of seedling of ‘Folha Murcha’ variety grafted on Rangpur Lemon occurs in the absence of shading. The 80% of shading treatment influenced negatively the plant growth.

Response of oranje Natal Folha Murcha (Citrus sinensis (L.) Osbeck) at diferent levels of irrigation

With the aim of studying the effect of the irrigation rate on the yield and fruit quality of sweet orange ( Citrus sinensis (L.) Osbeck) cv. Folha Murcha, an experiment was conducted in Sitio Jacutinga located in the county of Jeronimo Monteiro, Espirito Santo, Brazil, using orange of the variety Folha Murcha grafted on mandarim Cleopatra, with five years of age, spaced 5 m between rows and 4 m between plants within the line. Five treatments were implemented each with a different irrigation regime (L0 = without irrigation; L1 = 50% of PET; L2 = 75% of PET; L3 = 100% of PET and L4 = 125% of PET), defined based on potential evapotranspiration estimated by the method of Tank Class A. the experimental design was a randomized block with three replications consisting of nine plants in each repetition. In this study, yield per plant (kg), diameter and height of the fruit were evaluated. The irrigation regime 125% of the PET promoted the highest yield of orange Folha Murcha, under the conditions of this study.

Produtividade de laranjeira Folha Murcha enxertada em limoeiro Cravo sob adensamento de plantio

A citricultura brasileira passa por mudanças no padrão tecnológico, destacando-se o adensamento dos plantios. Dentro desse contexto, implantou-se em 1982 experimento para avaliação de cinco espaçamentos entre plantas (2,0; 3,0; 4,0; 5,0 e 6,0 metros) para laranjeira Folha Murcha, enxertada em limoeiro Cravo. O ensaio foi conduzido sem irrigação, fixando-se o espaçamento entrelinhas em 6,5 metros. Em complementação aos dados obtidos entre os anos de implantação e estabilização do pomar (1982 a 1993), são apresentados e discutidos neste trabalho resultados de avaliações realizadas do 12.o ao 22.º ano de cultivo (1994 a 2004). Calculou-se volume de copa a partir dos dados de altura e diâmetro das plantas, em 1995. Além disso, avaliou-se a produção de frutos por planta, produção acumulada e projeção da produtividade média (t ha–1) para cada espaçamento proposto. No espaçamento mais adensado (6,5×2,0 m), as plantas apresentaram menor volume de copa; em contrapartida, maior produtividade da laranjeira Folha Murcha foi observada nesse tratamento. Houve queda de produção nos anos mais avançados de cultivo, independentemente da densidade de plantio. O espaçamento 6,5×2,0 acarreta alta produtividade para laranjeira Folha Murcha, tornando a técnica do adensamento apta à adoção pelo citricultor.

Water balance and crop coefficient for the ‘Folha Murcha’ orange in the northwest region of Rio de Janeiro

A citricultura brasileira vem sendo explorada em uma diversidade de solos e climas em varias regioes do pais, estando seu principal eixo de desenvolvimento localizado no Sudeste. Na Regiao Noroeste do Estado do Rio de Janeiro, as condicoes de clima e solo sao favoraveis ao cultivo da laranjeira, exceto pelo volume e distribuicao da precipitacao pluvial durante o ano, ocorrendo periodos de deficit de agua no solo. O presente trabalho teve como objetivo obter os componentes e realizar o balanco hidrico de um Argissolo Vermelho-Amarelo do Noroeste Fluminense cultivado com laranjeira 'Folha Murcha', verificando, em onze periodos ao longo de 197 dias, diferencas decorrentes do local de monitoramento do solo e determinando, ainda, o coeficiente de cultura (Kc) e o nivel de atendimento da demanda hidrica da cultura (fator Ks). O trabalho foi realizado no Instituto Federal Fluminense em Bom Jesus do Itabapoana-RJ, no periodo de 13/08/2012 e 26/02/2013. Tres plantas foram monitoradas quanto aos componentes do balanco hidrico (precipitacao pluvial, escoamento superficial, armazenagem, drenagem profunda e ascensao capilar). Os resultados permitiram verificar que o consumo medio de agua pela planta durante todo o periodo foi de 2,29 mm dia-1, sendo que a maior demanda hidrica ocorreu nos meses de dezembro, janeiro e fevereiro. Obteve-se um valor medio de Kc de 0,88 e verificou-se que a disponibilidade de agua no solo nao atendeu de forma completa a demanda hidrica da planta, variando este atendimento de pleno (Ks = 1,0) ate apenas 36% (Ks = 0,36), indicando que na Regiao Noroeste Fluminense o desempenho da cultura pode ser incrementado pela irrigacao. Em relacao ao monitoramento do solo, pode-se concluir que, conforme a posicao em que o mesmo e realizado, os resultados do balanco hidrico da laranjeira 'Folha Murcha' podem divergir.

Evidence that ‘flying dragon’ trifoliate orange delays HLB symptom expression for four sweet orange cultivars, Tahiti lime and Okitsu mandarin

Huanglongbing (HLB), caused by Candidatus Liberibacter asiaticus and vectored by Diaphorina citri, was first reported in 2004 in Brazil and is currently widespread in Sao Paulo State. Brazil is the world’s largest sweet orange producer and has 49,000 ha cultivated with ‘Tahiti’ lime acid lime. Mandarin cultivation represents 5.5% of total citrus production in the country. In 2001, three experiments were planted in the Citrus Experimental Station (EECB), Bebedouro, Northern Sao Paulo State, where the first HLB symptomatic tree was detected in 2006. The initial objective was to evaluate the performance of ‘Folha Murcha’ sweet orange, ‘Tahiti’ acid lime and ‘Okitsu’ mandarin grafted on twelve rootstocks including Rangpur lime, Swingle citrumelo, Rubidoux and Flying Dragon (FD) trifoliate oranges. Cumulative HLB incidence (CI) was calculated in 2009. Folha Murcha and Tahiti lime trees on FD had lower CI values (6.7 and 10%) than trees on Rangpur lime (33.3 and 80%), Swingle citrumelo (46.7 and 66.7%) and Rubidoux (46.7 and 60%). CI was similar for Okitsu on FD, Carrizo citrange and HRS 827 (11.1%). In another field trial at EECB, Valencia, Hamlin and Natal were planted on FD in November 1994. Drip irrigation was installed in 2001. The first symptomatic plants in the area were detected in November 2008. In 2010, the 16 yr-old trees on FD have a lower CI (5.6%) than 20 yr-old sweet orange trees on Swingle citrumelo in an adjacent trial (CI = 35.4%). Our results indicated that FD rootstock could prolong the longevity of citrus orchards but more well-controlled studies of scion-rootstocks combinations with and without vector management are required.

Incidence of Huanglongbing in commercial orchards in northwest Paraná, Brazil

In the Parana state, Brazil, Huanglongbing has been advancing on the most important production areas. In this study the objective was monitoring the disease incidence in sweet orange varieties Pera, Valencia and Folha Murcha (leaf wilt) in commercial orchards in the northwest of the Parana state. The plants were grouped by age and management of the insect vector, Diaphorina citri, in 35 commercial orchards. Every three months a full assessment of the orchard was performed, totaling six evaluations in each orchard. This monitoring consisted of the walk in the street, or with platform, throughout the orchard, observing and noting the plants symptomatic for the disease. Orchards of Pera variety had a higher incidence of the disease when the plants were aged 0-5 years and in orchards over the age of 11 years and chemical management of psyllid was made only when their presence was detected. Pera orchards of ages 6 to 10 years and above 11 years, when the chemical management of insect occurred only by new shoots and without assessing the presence of the insect, also showed a higher incidence. The Folha Murcha was the variety with the lowest disease incidence, except when chemical management occurred without assessing the presence of the psyllid in orchards aged 6 to 10 years and above 11 years, and when insecticide applications were made every 20 days, without any evaluation of the presence of the vector.

Colonization and distribution patterns of Candidatus Liberibacter asiaticus in distinct citrus rootstocks

Author(s): Lopes, S. A.; Luiz, F. Q.B.F.; Stuchi, E. S. | Abstract: A study was conducted to assess (i) patterns of Las colonization in graft-inoculated 1-y-old seedlings of Cravo Rangpur lime, Sunki mandarin, and Swingle citrumelo and (ii) patterns of Las distribution in naturally infected 4 and 10-y-old trees of sweet oranges ‘Pera’ on Sunki and ‘Folha murcha’ on 11 rootstocks. The seedlings were inoculated at the trunk, 40 cm above the substrate level. Samples of bark were collected at the inoculation site, 10, 20, and 30 cm below it, and from the root 45, 75, 105, and 135 days after inoculation (dai). Samples from trees included symptomatic leaves and bark from the trunk (10 cm above or below the grafting line) and roots. The samples were analyzed through qPCR to estimate log Las genome/gram tissue. In seedlings Las colonization pattern was similar for all rootstocks. Las was detected in the root 45 dai or 3 months before the symptoms developed on leaves. In Swingle maxima titers were lower but reached a plateau faster (45 to 75 dai) than in Sunki or Cravo (75 to 135 dai) for all sampled sites. In the field the distribution pattern of Las in the trees was also similar for all rootstocks, with higher titers detected in the leaves (5.29±0.22) than in trunks (4.38±0.49; 3.78±0.27) or roots (3.38±0.28). No correlation existed between the amount of symptom on the canopy and Las titer in the root. This lack of correlation plus the fast movement of Las from the inoculation site down to the root may explain the failure of pruning to control HLB.

Distribuição do sistema radicular de porta-enxertos sob laranjeira ‘Folha Murcha’ em clima subtropical

The aim was to study the distribution of the root system of Rangpur lime (Citrus limonia Osbeck), Rough lemon (Citrus jambluri Lush.), Cleopatra mandarin (Citrus reshni Hort ex Tan.) and Trifoliata (Poncirus trifoliata (L.) Ralf.), under ‘Folha Murcha’ orange plant scion in subtropical climate, using the auger method. The samples were taken parallel to the line of planting (row) 0.5; 1.0; 1.5 and 2.0 m away from the trunk and perpendicular to the line of planting (inter-row) 0.5; 1.0; 1.5; 2.0; 2.5; 3.0 and 3.5 m away from the trunk. These samples were stratified into 0 – 0.1; 0.1 – 0.2; 0.2 – 0.4; 0.4 – 0.6 m deep. Dry mass, effective depth and effective distance of the root system of plants were determined. Randomized blocks design was used with four treatments and four replications, with one plant for each plot. Cleopatra mandarin plants had the highest total mass of roots 2.0; 2.5 and 3.0 m away from the trunck in inter-row, and in superficial layers of the following sampling sites: 0.5 and 1.0 m away from the trunk towards row and 1.5 e 2.0 m away from the trunck towards inter-row. Rough lemon plants showed greater effective depth of the roots in the rows than the other rootstocks.

Horticultural performance of ‘Folha Murcha’ sweet orange onto twelve rootstocks

Despite its outstanding position, the Brazilian citriculture is established on a very limited pool of varieties that limits its expansion and restricts the fruit availability throughout the year. This situation determines the urgent necessity of developing alternative scion and rootstock cultivars, with good performance under local conditions. ‘Folha Murcha’ sweet orange ( Citrus sinensis (L.) Osbeck) is a late-harvest cultivar, suitable both for the juice processing industry and the fresh fruit market, being described as tolerant to citrus canker ( Xanthomonas citri subsp. citri Schaad et al.), and less affected by citrus variegated chlorosis ( Xylella fastidiosa Wells et al.). A study was conducted in Bebedouro, São Paulo State, Brazil, to evaluate the horticultural performance of ‘Folha Murcha’ sweet orange budded onto 12 rootstocks: the citrandarin ‘Changsha’ mandarin ( Citrus reticulata Blanco) × Poncirus trifoliata ‘English Small’; the hybrid ‘Rangpur’ lime ( Citrus limonia Osbeck) × ‘Swingle’ citrumelo ( P. trifoliata (L.) Raf. × Citrus paradisi Macfad.); the trifoliates ( P. trifoliata (L.) Raf.) ‘Rubidoux’, ‘FCAV’, and ‘Flying Dragon’ ( P. trifoliata var. monstrosa); the ‘Sun Chu Sha Kat’ mandarin ( C. reticulata Blanco); the ‘Sunki’ mandarin ( Citrus sunki (Hayata) Hort. ex. Tanaka); the ‘Rangpur’ limes ( C. limonia Osbeck) ‘Cravo Limeira’ and ‘Cravo FCAV’; ‘Carrizo’ citrange ( C. sinensis × P. trifoliata), ‘Swingle’ citrumelo ( P. trifoliata × C. paradisi), and ‘Orlando’ tangelo ( C. paradisi × Citrus tangerina cv. ‘Dancy’). The experimental grove was planted in 2001, using a 7 m × 4 m spacing, in a randomized block design, with five replications and two plants per plot. No supplementary irrigation was applied. Fruit yield, canopy volume, tree tolerance to drought and to citrus variegated chlorosis, and fruit quality were assessed for each rootstock. Trees grafted onto the ‘Flying Dragon’ trifoliate were smaller in size, but had largest yield efficiency when compared to those grafted onto other rootstocks. Lower alternate bearing index was observed on trees budded onto ‘Cravo FCAV’ ‘Rangpur’ lime. Both ‘Rangpur’ lime rootstocks and the ‘Sunki’ mandarin induced higher tree tolerance to drought. The ‘Flying Dragon’ trifoliate induced better fruit quality and higher tolerance to citrus variegated chlorosis (CVC) to ‘Folha Murcha’ trees. A cluster multivariate analysis identified three groups of rootstocks with similar effects on ‘Folha Murcha’ tree performance. Among the 12 evaluated rootstocks, the ‘Flying Dragon’ trifoliate has a unique effect on plant growth, tolerance to drought and CVC, fruit yield and fruit quality of ‘Folha Murcha’ trees, and may be better suited for high-density plantings.

Nonlinear models for describing the Citrus Variegated Chlorosis in groves of two counties at northwestern Paraná state, Brazil

In Brazil, the production of sweet oranges has been threatened by the Citrus Variegated Chlorosis (CVC) incited by the gram-negative bacterium Xylella fastidiosa (Wells). Commercial citrus groves in two counties at the Northwestern Paraná state were evaluated to estimate the disease progression by using parameterizations of nonlinear models. Groves of Citrus sinensis Osbeck, variety “Pêra”, “Valência”, “Natal” and “Folha Murcha” had all the plants evaluated for the presence of disease symptoms. Thereafter, different parameterizations of the Logistic and Gompertz models were fitted to these data. The goodness of fit was evaluated by the intrinsic (IN) and parameter-effects (PE) curvatures of Bates and Watts, the bias of Box and the Hougaard measures of skewness. In Loanda, the best model was the Fermi-Dirac, and in Nova Esperança the data were best fitted to the parameterization L5, which is also a parameterization from the Logistic model.

Incidência de &lt;em&gt;Dilobopterus costalimai&lt;/em&gt; Young e &lt;em&gt;Acrogonia citrina&lt;/em&gt; Marucci &amp; Cavichioli, em pomares cítricos no noroeste paranaense

The sharpshooters of the families Cicadellidae and Cercopidae are vectors of Xylella fastidiosa (Wells), which causes citrus variegated chlorosis. This disease causes severe damage to the Paraná citrus industry, and it has been studied in Brazil since 1987, when it was discovered for the first time in the area of Colina, SP. The vectors transmit X. fastidiosa when they feed on the xylem sap, where the bacteria settles, obstructing the passage of the sap. This work had the objective of evaluating the occurrence of the vector sharpshooter Dilobopterus costalimai and Acrogonia citrina in a commercial citrus orchard during the period between July 2004 and August 2006. The experiment was accomplished in the Laranjeiras I farm, in the city of Nova Esperança, northwestern Paraná. The collections were undertaken monthly, and yellow stick traps (Biocontrole®) was used as a sampling method in Folha murcha, Valência, Pêra and Natal oranges trees [Citrus sinensis (L.) Osbeck]. In Pêra and Valência trees, the most often captured sharpshooter was Dilobopterus costalimai. The months of higher occurrence of these species were between December and May of each year.

Identificação de híbridos de citros resistentes à mancha-marrom-de-alternária por meio de fAFLP e testes de patogenicidade

O objetivo deste trabalho foi identificar híbridos, oriundos de hibridações controladas entre 'Folha Murcha' x 'Ponkan' e testá-los quanto à resistência a Alternaria alternata f. sp. citri. As plântulas foram obtidas via cultura in vitro de embriões. Utilizou-se o marcador molecular fAFLP para identificação dos híbridos e, em seguida, realizou-se o teste de patogenicidade nos híbridos com isolados de Alternaria alternata f. sp. citri, em condições de laboratório. Os pares de primers EcoRI AAG - MseI CAG e EcoRI ACC - MseI CAA foram os mais eficientes na identificação dos híbridos, os quais identificaram 48,5% de híbridos. Os híbridos F64, F108, F111, F113, F131 e F139 são potencialmente resistentes a Alternaria alternata f. sp. citri.